Java+MyEclipse+Tomcat (六)详解Servlet和DAO数据库增删改查操作

此篇文章主要讲述DAO、Java Bean和Servlet实现操作数据库，把链接数据库、数据库操作、前端界面显示分模块化实现。其中包括数据的CRUD增删改查操作，并通过一个常用的JSP网站前端模板界面进行描述。参考前文：
  Java+MyEclipse+Tomcat (一)配置过程及jsp网站开发入门
   Java+MyEclipse+Tomcat (二)配置Servlet及简单实现表单提交
   Java+MyEclipse+Tomcat (三)配置MySQL及查询数据显示在JSP网页中
   Java+MyEclipse+Tomcat (四)Servlet提交表单和数据库操作
  Java+MyEclipse+Tomcat (五)DAO和Java Bean实现数据库和界面分开操作
免费资源下载地址：
  http://download.csdn.net/detail/eastmount/8733385

PS:这篇文章可以认为是对前面五篇文章的一系列总结和应用，同时我认为理解该篇文章基本就能简单实现一个基于数据库操作的JSP网站，对你的课程项目或毕设有所帮助！但同时没有涉及事务、触发器、存储过程、并发处理等数据库知识，也没有Struts、Hibernate、Spring框架知识，它还是属于基础性文章吧！希望对你有所帮助~

一. 项目结构

该项目的结构如下图所示：

这是典型的DAO模式，其中bean文件夹中TrainManage.java类封装了数据库表TrainManage中的属性和get/set操作；DAO文件夹中TrainManageDAO.java是对类TrainManage（或火车表）的数据库增删改查操作；util中JDBCConnect.java主要是连接数据库MySQL的操作；servlet主要是POST方法请求表单。

二. 数据库初始化操作

打开MySQL，输入默认超级root用户的密码，然后数据库的操作如下代码：

--创建数据库
create database ManageTrain;
--使用数据库
use ManageTrain;
--创建表 车次信息管理表 主键:车次
--属性：车次 出发地 目的地 行车时间 硬座票价 软座票价 硬卧票价 软卧票价 车辆路线
create table TrainManage(trainid varchar(20) primary key,start varchar(20),end varchar(20),time varchar(20),yzprice decimal(10,1),rzprice decimal(10,1),ywprice decimal(10,1),rwprice decimal(10,1),root varchar(200)
);
--插入数据
insert TrainManage (trainid,start,end,time,yzprice,rzprice,ywprice,rwprice,root)values ("T87","Beijing","Guiyang","28小时","278","320","464.5","550","Beijing Shijiazhuang Guiyang");
insert TrainManage (trainid,start,end,time,yzprice,rzprice,ywprice,rwprice,root)values ("T87","Guiyang","Beijing","28小时","278","320","464.5","550","Guiyang Shijiazhuang Beijing");
--查询数据
select * from TrainManage;

注意：上面操作在MySQL黑框中输出增删改查的SQL语言就可以，不要把中文注释也执行。同时设置所有编码方式都统一为utf-8防止乱码，数据库表结构如下图所示：

三. 简单查询操作DAO方法

新建Web Project，项目名为“TrainDatabase”,对火车车次数据库的增删改查。
运行效果如下图所示：

1.在src下新建文件夹util，然后添加类JDBCConnect.java。代码如下：
主要是调用getConnection(url, userName, password)方法进行连接数据库操作，数据库的名称为TrainManage，默认的连接对象为root，密码为123456。同时定义两个函数executeUpdate()执行无参数的SQL语句操作和有参数的SQL语句操作。

package util;import java.sql.*;
import com.mysql.jdbc.Driver;public class JDBCConnect {//获取默认数据库连接public static Connection getConnection() throws SQLException {return getConnection("ManageTrain", "root", "123456"); //数据库名 默认用户 密码}//连接数据库   参数:数据库名 root登录名 密码public static Connection getConnection(String dbName, String userName,String password) throws SQLException {String url = "jdbc:mysql://localhost:3306/" + dbName + "?characterEncoding=utf-8";//连接MySQL"com.mysql.jdbc.Driver"DriverManager.registerDriver(new Driver());return DriverManager.getConnection(url, userName, password);}//设置 PreparedStatement 参数 public static void setParams(PreparedStatement preStmt, Object... params)throws SQLException {if (params == null || params.length == 0)return;for (int i = 1; i <= params.length; i++) {Object param = params[i - 1];if (param == null) {preStmt.setNull(i, Types.NULL);} else if (param instanceof Integer) {preStmt.setInt(i, (Integer) param);} else if (param instanceof String) {preStmt.setString(i, (String) param);} else if (param instanceof Double) {preStmt.setDouble(i, (Double) param);} else if (param instanceof Long) {preStmt.setDouble(i, (Long) param);} else if (param instanceof Timestamp) {preStmt.setTimestamp(i, (Timestamp) param);} else if (param instanceof Boolean) {preStmt.setBoolean(i, (Boolean) param);} else if (param instanceof Date) {preStmt.setDate(i, (Date) param);}}}//执行 SQL，返回影响的行数 异常处理public static int executeUpdate(String sql) throws SQLException {return executeUpdate(sql, new Object[] {});}//带参数执行SQL，返回影响的行数 异常处理public static int executeUpdate(String sql, Object... params)throws SQLException {Connection conn = null;PreparedStatement preStmt = null;try {conn = getConnection();preStmt = conn.prepareStatement(sql);setParams(preStmt, params);return preStmt.executeUpdate(); //执行SQL操作} finally {if (preStmt != null)preStmt.close();if (conn != null)conn.close();}}
}

2.在src下新建文件夹bean，然后添加类TrainManage.java。代码如下：

package bean;public class TrainManage {private String trainid;       //车次private String start;         //出发地private String end;           //目的地private String time;          //行车时间private float yzprice;        //硬座票价private float rzprice;        //软座票价private float ywprice;        //硬卧票价private float rwprice;        //软卧票价private String root;          //车辆路线 public String getTrainid() { return trainid; }public String getStart() { return start; }public String getEnd() { return end; }public String getTime() { return time; }public Float getYzprice() { return yzprice; }public Float getRzprice() { return rzprice; }public Float getYwprice() { return ywprice; }public Float getRwprice() { return rwprice; }public String getRoot() { return root; }public void setTrainid(String str) { this.trainid =  str; }public void setStart(String str) { this.start =  str; }public void setEnd(String str) { this.end = str; }public void setTime(String str) { this.time = str; }public void setYzprice(Float price) { this.yzprice = price; }public void setRzprice(Float price) { this.rzprice = price; }public void setYwprice(Float price) { this.ywprice = price; }public void setRwprice(Float price) { this.rwprice = price; }public void setRoot(String str) { this.root = str; }
}

3.在src下新建文件夹DAO，然后添加类StudentDAO.java。代码如下：

通常DAO（Data Access Object）数据访问对象是负责与数据库连接，主要功能执行对数据表的CUDR操作（创建、更新、删除、查询）。每个数据表都定义一个DAO接口或类实现，实现对此表的读写操作。换句话说，就是在域名.项目.模块.dao文件夹下创建个DAO类即可。

package DAO;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import bean.TrainManage;
import util.JDBCConnect;public class TrainManageDAO {//插入车次public static int insert(TrainManage train) throws Exception {String sql = "INSERT INTO TrainManage (trainid,start,end,time,yzprice,rzprice,ywprice,rwprice,root) " +"VALUES ('" + train.getTrainid() +"','"+ train.getStart() +"','"+ train.getEnd() +"','"+ train.getTime() +"','"+ train.getYzprice() +"','"+ train.getRzprice() +"','"+ train.getYwprice() +"','"+ train.getRwprice() +"','"+ train.getRoot()  +"');";System.out.println(sql);return JDBCConnect.executeUpdate(sql);/*** 总是报错  No value specified for parameter 5* 很多原因是 insert into train (?,?,?) values (?,?,?) 前面不应该是问号 * 但我的怀疑是参数过多使用executeUpdate(sql,?,?,?...)方法是错误* * String sql = "INSERT INTO TrainManage (trainid,start,end,time,yzprice,rzprice,ywprice,rwprice,root) VALUES (?,?,?,?,?,?,?,?,?);";* System.out.println(sql);* return JDBCConnect.executeUpdate(sql, train.getTrainid(), train.getStart(), train.getEnd(),*        train.getTime(), train.getYzprice(), train.getRzprice(), train.getYwprice(), *      train.getRwprice(), train.getRoot());*/}//更新车次public static int update(TrainManage train) throws Exception {String sql = "UPDATE TrainManage SET start = ?, end = ? WHERE trainid = ? ";return JDBCConnect.executeUpdate(sql, train.getStart(), train.getEnd(), train.getTrainid());}//删除操作public static int delete(String id) throws Exception {String sql = "DELETE FROM TrainManage WHERE trainid = ? ";return JDBCConnect.executeUpdate(sql, id);}//查找记录 某车次public static TrainManage find(String id) throws Exception {String sql = "SELECT * FROM TrainManage WHERE trainid = ? ";Connection conn = null;PreparedStatement preStmt = null;ResultSet rs = null;try {//链接数据库执行SQL语句conn = JDBCConnect.getConnection(); //连接默认数据库preStmt = conn.prepareStatement(sql);preStmt.setString(1, id);rs = preStmt.executeQuery();//获取查询结果if (rs.next()) {TrainManage train = new TrainManage();train.setTrainid(rs.getString("trainid"));train.setStart(rs.getString("start"));train.setEnd(rs.getString("end"));train.setTime(rs.getString("time"));train.setYzprice(rs.getFloat("yzprice"));train.setYwprice(rs.getFloat("ywprice"));train.setRzprice(rs.getFloat("rzprice"));train.setRwprice(rs.getFloat("rwprice"));train.setRoot(rs.getString("root"));return train;} else {return null;}} finally { //依次关闭 记录集 声明 连接对象if (rs != null)rs.close();if (preStmt != null)preStmt.close();if (conn != null)conn.close();}}//查找记录 起始站 达到站public static List<TrainManage> findStartEnd(String start,String end) throws Exception {List<TrainManage> list = new ArrayList<TrainManage>();String sql = null; Connection conn = null;Statement statement = null;ResultSet rs = null;//判断SQL语句if(start==""&&end=="") {sql = "SELECT * FROM TrainManage;";} else if(end=="") {sql = "SELECT * FROM TrainManage WHERE start = '"+ start + "';";} else if(start=="") {sql = "SELECT * FROM TrainManage WHERE end = '"+ end + "';";} else {sql = "SELECT * FROM TrainManage WHERE start = '" + start + "' and end = '"+ end +"';"; }//执行try {//链接数据库执行SQL语句conn = JDBCConnect.getConnection(); //连接默认数据库statement = conn.createStatement();System.out.println(start+" "+end);System.out.println(sql);rs = statement.executeQuery(sql);//获取查询结果while(rs.next()) {TrainManage train = new TrainManage();train.setTrainid(rs.getString("trainid"));train.setStart(rs.getString("start"));train.setEnd(rs.getString("end"));train.setTime(rs.getString("time"));train.setYzprice(rs.getFloat("yzprice"));train.setYwprice(rs.getFloat("ywprice"));train.setRzprice(rs.getFloat("rzprice"));train.setRwprice(rs.getFloat("rwprice"));train.setRoot(rs.getString("root"));list.add(train);}} catch (Exception e) {System.out.println("错误："+e.getMessage());  }finally { //依次关闭 记录集 声明 连接对象if (rs != null)rs.close();if (statement != null)statement.close();if (conn != null)conn.close();}return list;}//查询所有车次信息public static List<TrainManage> listStudents() throws Exception {List<TrainManage> list = new ArrayList<TrainManage>();String sql = "SELECT * FROM TrainManage";Connection conn = null;PreparedStatement preStmt = null;ResultSet rs = null;try {conn = JDBCConnect.getConnection();preStmt = conn.prepareStatement(sql);rs = preStmt.executeQuery();while (rs.next()) {//设置数据库中表参数 否则报错java.sql.SQLException: Column 'id' not found.TrainManage train = new TrainManage();train.setTrainid(rs.getString("trainid"));      train.setStart(rs.getString("start"));train.setEnd(rs.getString("end"));train.setTime(rs.getString("time"));train.setYzprice(rs.getFloat("yzprice"));train.setYwprice(rs.getFloat("ywprice"));train.setRzprice(rs.getFloat("rzprice"));train.setRwprice(rs.getFloat("rwprice"));train.setRoot(rs.getString("root"));list.add(train);}   } finally {if (rs != null)rs.close();if (preStmt != null)preStmt.close();if (conn != null)conn.close();}return list;}
}

4.在WebRoot文件夹下创建trainManage.jsp文件，页面布局代码如下：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<jsp:directive.page import="DAO.TrainManageDAO"/>
<jsp:directive.page import="java.util.List"/>
<%  List trainList = TrainManageDAO.listStudents();  request.setAttribute("trainList", trainList);
%>   <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>火车卡订票系统管理系统</title></head><body><div align="center"><div class="trainCSS"><table width="1024"  height="150" cellpadding="0" cellspacing="0"><tr><td colspan="2"><img src="./image/logo.jpg" alt="logo" width="1024" height="149">       </td></tr>      <tr><td width="205"  bgcolor="#b7d7ec"><p align="center"><script language=JavaScript>today=new Date();function initArray(){this.length=initArray.arguments.length;for(var i=0;i<this.length;i++)this[i+1]=initArray.arguments[i];  }var d=new initArray("星期日","星期一","星期二","星期三","星期四",   "星期五","星期六");document.write("<font color=##ff0000 style='font-size:12pt;font-family: 宋体'> ",today.getYear()+1900,"年",today.getMonth()+1,"月",today.getDate(),"日    ",d[today.getDay()+1],"</font>" );</script> </p> </td> <td width="819" bgcolor="#b7d7ec"><marquee  direction="left" οnmοuseοver=this.stop() οnmοuseοut=this.start() scrollAmount=3 scrollDelay=100><FONT style="FONT-SIZE: 18px"color=blue>欢迎使用火车票订票系统管理系统 ，如有不足，敬请指导！</FONT></marquee></td></tr><tr><td height="12"></td></tr></table></div><div class="trainCSS"><table border="0" width="1024" cellpadding="0" cellspacing="0"><tr><td width="130" bgcolor="#dfeaf1" valign="top"><table width="100%" cellpadding="0" cellspacing="0"  border="0"><tr><td height="10"></td></tr><tr><td align="center">  <font size="3" color="blue">管理员：xxx，欢迎您！</font></td></tr><tr><td height="10"></td></tr><tr><td align="center"><p><a href="trainManage.jsp"><img src="data:image/ccxxgl-xz.jpg" width="194" height="37" border="0"></a><td> </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="buyManage.jsp"><img src="data:image/dpgl.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="peopleManage.jsp"><img src="data:image/hygl.jpg" width="194" height="37" border="0"></a></td></tr>                 <tr><td height="10"></td></tr><tr><td align="center"><a href="serverManage.jsp">                                   <img src="data:image/spqktj.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="infoManage.jsp"><img src="data:image/lygl.jpg" width="194" height="37" border="0"></a>                               </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="exitManage.jsp"><img src="data:image/exit.jpg" width="194" height="37" border="0"></a>                                </td></tr></table></td><td><table width="100%" height="350" border="1"  cellpadding="0" cellspacing="0"  bgcolor="#dfeaf1"><tr><TD align="center" valign="top" style="padding-left:20px;padding-top:10px;"><div align="left">当前位置: <a href="homepage.jsp">首页</a> > 车次信息管理</div><br /><br /><form action="trainManageSelect.jsp" method="post"><!-- html:form为struts -->出发地: <input type="text" id="start" name="start" style='font-size:18px' width=200/>到达地: <input type="text" id="end" name="end" style='font-size:18px'/><br /><br /><input type="submit" name="Select" value="查询车次" style='font-size:18px'/><a href="trainManageInsert.jsp" style='font-size:20px'>插入车次</a></form><table border="2" bordercolor="#12A0F5"> <tr align=center><td>火车列次</td><td>出发地</td><td>目的地</td><td>行车时间</td><td>硬座票价</td><td>软座票价</td><td>硬卧票价</td><td>软卧票价</td><td>车辆路线</td><td>信息操作</td></tr><c:forEach items="${trainList}" var="train">  <tr align=center>  <td>${train.trainid}</td>  <td>${train.start}</td>  <td>${train.end}</td>  <td>${train.time}</td>  <td>${train.yzprice}</td>  <td>${train.rzprice}</td>  <td>${train.ywprice}</td>  <td>${train.rwprice}</td> <td><A href="trainManageDetail.jsp?action=see&id=${train.trainid}">查看</A></td> <td>  <a href="trainManageUpdate.jsp?action=edit&id=${train.trainid}">修改</a>  <a href="trainManageDelete.jsp?action=del&id=${train.trainid}"   οnclick="return confirm('确定删除?')">删除</a>  </td>  </tr>  </c:forEach></table><br /><br />                                              </TD></tr></table></td></tr><tr><td height="20"></td></tr></table></div>     <div class="div"><!-- 底部版权所有界面 --><TABLE class=wrapper border=0 cellSpacing=0 cellPadding=0 width="100%" align=center><TBODY><TR><TD style="LINE-HEIGHT: 100%" align="center"> <HR style="WIDTH: 96%; HEIGHT: 4px; COLOR: #02457c"><font size="2"> <SCRIPT language=javascript src=""></SCRIPT><!-- target=_blank开启新的网页 --><BR><A href="aboutme.jsp">关于我们</A> | <A href="wzsm.jsp" >网站声明</A> <BR>版权所有&copy;2014-2015 北京邮电大学 Eastmount   <BR>京ICP备10009636号 </font></TD></TR></TBODY></TABLE></div></div></body>
</html>

5在WebRoot路径下创建image文件夹，并添加jsp中需要使用的图片资源。
6.在WebRoot/WEB-INF/lib文件夹中添加mysql-connector-java-5.1.15-bin.jar文件，访问MySQL数据库需要用到。
7.右键项目，Run As在Tomcat 7.x下即可运行，效果如前图所示。
其中JSP文件与DAO的交互核心代码如下：

<jsp:directive.page import="DAO.TrainManageDAO"/>
<jsp:directive.page import="java.util.List"/>
<%  List trainList = TrainManageDAO.listStudents();  request.setAttribute("trainList", trainList);
%>
...
<table border="2" bordercolor="#12A0F5">
<tr align=center><td>火车列次</td><td>出发地</td><td>目的地</td><td>行车时间</td><td>硬座票价</td><td>软座票价</td><td>硬卧票价</td><td>软卧票价</td><td>车辆路线</td><td>信息操作</td>
</tr>
<c:forEach items="${trainList}" var="train">
<tr align=center>  <td>${train.trainid}</td>  <td>${train.start}</td>  <td>${train.end}</td>  <td>${train.time}</td>  <td>${train.yzprice}</td>  <td>${train.rzprice}</td>  <td>${train.ywprice}</td>  <td>${train.rwprice}</td> <td><A href="trainManageDetail.jsp?action=see&id=${train.trainid}">查看</A></td> <td>  <a href="trainManageUpdate.jsp?action=edit&id=${train.trainid}">修改</a>  <a href="trainManageDelete.jsp?action=del&id=${train.trainid}"   οnclick="return confirm('确定删除?')">删除</a>  </td>
</tr>
</c:forEach>
</table>

四. 关键字查询操作

关键字查询运行截图如下图所示：

该步骤只需要在WebRoot文件夹下创建trainManageSelect.jsp即可，代码如下：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<jsp:directive.page import="DAO.TrainManageDAO"/>
<jsp:directive.page import="bean.TrainManage"/>
<jsp:directive.page import="java.util.List"/>
<%  request.setCharacterEncoding("UTF-8");response.setCharacterEncoding("UTF-8");String mstart = request.getParameter("start");String mend = request.getParameter("end");List<TrainManage> trainList = TrainManageDAO.findStartEnd(mstart,mend); //List trainList = TrainManageDAO.listStudents();  request.setAttribute("trainList", trainList);
%>   <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>火车卡订票系统管理系统</title></head><body><div align="center"><div class="trainCSS"><table width="1024"  height="150" cellpadding="0" cellspacing="0"><tr><td colspan="2"><img src="./image/logo.jpg" alt="logo" width="1024" height="149">       </td></tr>      <tr><td width="205"  bgcolor="#b7d7ec"><p align="center"><script language=JavaScript>today=new Date();function initArray(){this.length=initArray.arguments.length;for(var i=0;i<this.length;i++)this[i+1]=initArray.arguments[i];  }var d=new initArray("星期日","星期一","星期二","星期三","星期四",   "星期五","星期六");document.write("<font color=##ff0000 style='font-size:12pt;font-family: 宋体'> ",today.getYear()+1900,"年",today.getMonth()+1,"月",today.getDate(),"日    ",d[today.getDay()+1],"</font>" );</script> </p> </td> <td width="819" bgcolor="#b7d7ec"><marquee  direction="left" οnmοuseοver=this.stop() οnmοuseοut=this.start() scrollAmount=3 scrollDelay=100><FONT style="FONT-SIZE: 18px"color=blue>欢迎使用火车票订票系统管理系统 ，如有不足，敬请指导！</FONT></marquee></td></tr><tr><td height="12"></td></tr></table></div><div class="trainCSS"><table border="0" width="1024" cellpadding="0" cellspacing="0"><tr><td width="130" bgcolor="#dfeaf1" valign="top"><table width="100%" cellpadding="0" cellspacing="0"  border="0"><tr><td height="10"></td></tr><tr><td align="center">  <font size="3" color="blue">管理员：xxx，欢迎您！</font></td></tr><tr><td height="10"></td></tr><tr><td align="center"><p><a href="trainManage.jsp"><img src="data:image/ccxxgl-xz.jpg" width="194" height="37" border="0"></a><td> </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="buyManage.jsp"><img src="data:image/dpgl.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="peopleManage.jsp"><img src="data:image/hygl.jpg" width="194" height="37" border="0"></a></td></tr>                 <tr><td height="10"></td></tr><tr><td align="center"><a href="serverManage.jsp">                                   <img src="data:image/spqktj.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="infoManage.jsp"><img src="data:image/lygl.jpg" width="194" height="37" border="0"></a>                               </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="exitManage.jsp"><img src="data:image/exit.jpg" width="194" height="37" border="0"></a>                                </td></tr></table></td><td><table width="100%" height="350" border="1"  cellpadding="0" cellspacing="0"  bgcolor="#dfeaf1"><tr><TD align="center" valign="top" style="padding-left:20px;padding-top:10px;"><div align="left">当前位置: <a href="homepage.jsp">首页</a> > 车次信息管理</div><br /><br /><form action="trainManageSelect.jsp" method="post"><!-- html:form为struts -->出发地: <input type="text" id="start" name="start" style='font-size:18px' width=200/>到达地: <input type="text" id="end" name="end" style='font-size:18px'/><br /><br /><input type="submit" name="Select" value="查询车次" style='font-size:18px'/><a href="trainManageInsert.jsp" style='font-size:20px'>插入车次</a></form><table border="2" bordercolor="#12A0F5"> <tr align=center><td>火车列次</td><td>出发地</td><td>目的地</td><td>行车时间</td><td>硬座票价</td><td>软座票价</td><td>硬卧票价</td><td>软卧票价</td><td>车辆路线</td><td>信息操作</td></tr><c:forEach items="${trainList}" var="train">  <tr align=center>  <td>${train.trainid}</td>  <td>${train.start}</td>  <td>${train.end}</td>  <td>${train.time}</td>  <td>${train.yzprice}</td>  <td>${train.rzprice}</td>  <td>${train.ywprice}</td>  <td>${train.rwprice}</td> <td><A href="trainManageDetail.jsp?action=see&id=${train.trainid}">查看</A></td> <td>  <a href="trainManageUpdate.jsp?action=edit&id=${train.trainid}">修改</a>  <a href="trainManageDelete.jsp?action=del&id=${train.trainid}"   οnclick="return confirm('确定删除?')">删除</a>  </td>  </tr>  </c:forEach></table><br /><br />                                              </TD></tr></table></td></tr><tr><td height="20"></td></tr></table></div>     <div class="div"><!-- 底部版权所有界面 --><TABLE class=wrapper border=0 cellSpacing=0 cellPadding=0 width="100%" align=center><TBODY><TR><TD style="LINE-HEIGHT: 100%" align="center"> <HR style="WIDTH: 96%; HEIGHT: 4px; COLOR: #02457c"><font size="2"> <SCRIPT language=javascript src=""></SCRIPT><!-- target=_blank开启新的网页 --><BR><A href="aboutme.jsp">关于我们</A> | <A href="wzsm.jsp" >网站声明</A> <BR>版权所有&copy;2014-2015 北京邮电大学 Eastmount   <BR>京ICP备10009636号 </font></TD></TR></TBODY></TABLE></div></div></body>
</html>

调用的trainManageDAO.java中的函数findStartEnd(String start,String end)如下，它如果不输入则进行所有查找，也支持单方面出发或到达查找：

//查找记录 某车次public static List<TrainManage> findStartEnd(String start,String end) throws Exception {List<TrainManage> list = new ArrayList<TrainManage>();String sql = null; Connection conn = null;Statement statement = null;ResultSet rs = null;//判断SQL语句if(start==""&&end=="") {sql = "SELECT * FROM TrainManage;";} else if(end=="") {sql = "SELECT * FROM TrainManage WHERE start = '"+ start + "';";} else if(start=="") {sql = "SELECT * FROM TrainManage WHERE end = '"+ end + "';";} else {sql = "SELECT * FROM TrainManage WHERE start = '" + start + "' and end = '"+ end +"';"; }//执行try {//链接数据库执行SQL语句conn = JDBCConnect.getConnection(); //连接默认数据库statement = conn.createStatement();System.out.println(start+" "+end);System.out.println(sql);rs = statement.executeQuery(sql);//获取查询结果while(rs.next()) {TrainManage train = new TrainManage();train.setTrainid(rs.getString("trainid"));train.setStart(rs.getString("start"));train.setEnd(rs.getString("end"));train.setTime(rs.getString("time"));train.setYzprice(rs.getFloat("yzprice"));train.setYwprice(rs.getFloat("ywprice"));train.setRzprice(rs.getFloat("rzprice"));train.setRwprice(rs.getFloat("rwprice"));train.setRoot(rs.getString("root"));list.add(train);}} catch (Exception e) {System.out.println("错误："+e.getMessage());  }finally { //依次关闭 记录集 声明 连接对象if (rs != null)rs.close();if (statement != null)statement.close();if (conn != null)conn.close();}return list;}

其中核心步骤如下：
1.在trainManage.jsp提交POST表单出发地(<input id="start")和到达地(<input id="end")，提交给trainManageSelect.jsp；
2.在trainManageSelect.jsp中通过获取出发地和到达地，并执行DAO中的TrainManageDAO.java中关键字查找函数:
String mstart = request.getParameter("start");
String mend = request.getParameter("end");
List<TrainManage> trainList = TrainManageDAO.findStartEnd(mstart,mend);
request.setAttribute("trainList", trainList);
3.在JSP中通过EL循环显示结果如下：
<c:forEach items="${trainList}" var="train">
<tr align=center>
<td>${train.trainid}</td>
<td>${train.start}</td>
...
</tr>
</c:forEach>
PS：同时在这过程中你会遇到执行关键字中文查询时显示乱码。
在trainManageSelect.java文件中通过函数findStartEnd(start,end)打桩输出提交表单"北京长沙"如下所示：

而且我的服务器、MySQL、JSP、URL3306地址中都设置了UTF-8编码方式，最终解决有两个方面：
第一个方面是在进行SQL查找时，我最初使用的第一种方法核心代码：

String sql = "SELECT * FROM TrainManage WHERE start = ? and end = ? ;";
Connection conn = JDBCConnect.getConnection(); //连接默认数据库
PreparedStatement preStmt = conn.prepareStatement(sql);
preStmt.setString(1, start);
preStmt.setString(2, end);
ResultSet rs = preStmt.executeQuery();

但是在查询英文Beijing => Guizhou 时能正确显示，而中文就没有结果，后改为带引号（"'"+string+"'"）的参数方式，核心代码如下：

String sql = "SELECT * FROM TrainManage WHERE start = '" + start + "' and end = '"+ end +"';";
Connection conn = JDBCConnect.getConnection(); //连接默认数据库
Statement statement = conn.createStatement();
ResultSet rs = statement.executeQuery(sql);
while(rs.next()){...}

后来使用该方法仍然存在乱码，但是这次我发现了原因，在form提交表单时采用Get方法就会出现中文乱码，虽然URL中显示的是：
http://localhost:8080/TrainDatabase/trainManageSelect.jsp?start=北京&end=长沙&sumbit=提交
但是可能URL转String出现乱码的，改为POST即可实现正常查询，显示正常中文。
注意：前提是我的所有编码字符集都统一为UTF-8。

五. 插入操作调用Servlet

该部分运行截图如下图所示：

在src中创建文件夹servlet，同时创建Servlet文件InsertTrainAction.java。

package servlet;import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import bean.TrainManage;
import util.JDBCConnect;
import DAO.TrainManageDAO;public class InsertTrainAction extends HttpServlet {public InsertTrainAction() {super();}public void destroy() {super.destroy(); // Just puts "destroy" string in log// Put your code here}//The doGet method of the servlet     public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");out.println("<HTML>");out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");out.println("  <BODY>");out.print("    This is ");out.print(this.getClass());out.println(", using the GET method");out.println("  </BODY>");out.println("</HTML>");out.flush();out.close();}//The doPost method of the servletpublic void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setCharacterEncoding("UTF-8"); //设置输出编码  request.setCharacterEncoding("UTF-8");  try {//插入数据库String m_trainid = request.getParameter("trainid");String m_start = request.getParameter("start");String m_end = request.getParameter("end");String m_time = request.getParameter("time");String m_yz = request.getParameter("yzprice");Float m_yzprice = Float.parseFloat(m_yz);String m_rz = request.getParameter("rzprice");Float m_rzprice = Float.parseFloat(m_rz);String m_yw = request.getParameter("ywprice");Float m_ywprice = Float.parseFloat(m_yw);String m_rw = request.getParameter("rwprice");Float m_rwprice = Float.parseFloat(m_rw);String m_root = request.getParameter("root");TrainManage train = new TrainManage();train.setTrainid(m_trainid);train.setStart(m_start);train.setEnd(m_end);train.setTime(m_time);train.setYzprice(m_yzprice);train.setRzprice(m_rzprice);train.setYwprice(m_ywprice);train.setRwprice(m_rwprice);train.setRoot(m_root);int success  = TrainManageDAO.insert(train);  request.setAttribute("success", success);  //设置全路径 否则trainManage.jsp跳转到servlet/trainManage.jsp路径下不存在response.sendRedirect("http://localhost:8080/TrainDatabase/trainManage.jsp");  } catch(Exception e) {System.out.println("错误："+e.getMessage());  response.sendRedirect("http://localhost:8080/TrainDatabase/trainManage.jsp");  }}public void init() throws ServletException {// Put your code here}}

它会自动配置WebRoot/WEB-INF/web.xml文件中servlet和其映射。同时在WebRoot中添加trainManageInsert.jsp。

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session = "true" %>
<jsp:directive.page import="DAO.TrainManageDAO"/>
<jsp:directive.page import="bean.TrainManage"/>
<jsp:directive.page import="java.util.List"/> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>火车卡订票系统管理系统</title></head><body><div align="center"><div class="trainCSS"><table width="1024"  height="150" cellpadding="0" cellspacing="0"><tr><td colspan="2"><img src="./image/logo.jpg" alt="logo" width="1024" height="149">       </td></tr>      <tr><td width="205"  bgcolor="#b7d7ec"><p align="center"><script language=JavaScript>today=new Date();function initArray(){this.length=initArray.arguments.length;for(var i=0;i<this.length;i++)this[i+1]=initArray.arguments[i];  }var d=new initArray("星期日","星期一","星期二","星期三","星期四",   "星期五","星期六");document.write("<font color=##ff0000 style='font-size:12pt;font-family: 宋体'> ",today.getYear()+1900,"年",today.getMonth()+1,"月",today.getDate(),"日    ",d[today.getDay()+1],"</font>" );</script> </p> </td> <td width="819" bgcolor="#b7d7ec"><marquee  direction="left" οnmοuseοver=this.stop() οnmοuseοut=this.start() scrollAmount=3 scrollDelay=100><FONT style="FONT-SIZE: 18px"color=blue>欢迎使用火车票订票系统管理系统 ，如有不足，敬请指导！</FONT></marquee></td></tr><tr><td height="12"></td></tr></table></div><div class="trainCSS"><table border="0" width="1024" cellpadding="0" cellspacing="0"><tr><td width="130" bgcolor="#dfeaf1" valign="top"><table width="100%" cellpadding="0" cellspacing="0"  border="0"><tr><td height="10"></td></tr><tr><td align="center">  <font size="3" color="blue">管理员：xxx，欢迎您！</font></td></tr><tr><td height="10"></td></tr><tr><td align="center"><p><a href="trainManage.jsp"><img src="data:image/ccxxgl-xz.jpg" width="194" height="37" border="0"></a><td> </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="buyManage.jsp"><img src="data:image/dpgl.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="peopleManage.jsp"><img src="data:image/hygl.jpg" width="194" height="37" border="0"></a></td></tr>                 <tr><td height="10"></td></tr><tr><td align="center"><a href="serverManage.jsp">                                   <img src="data:image/spqktj.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="infoManage.jsp"><img src="data:image/lygl.jpg" width="194" height="37" border="0"></a>                               </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="exitManage.jsp"><img src="data:image/exit.jpg" width="194" height="37" border="0"></a>                                </td></tr></table></td><td><table width="100%" height="350" border="1"  cellpadding="0" cellspacing="0"  bgcolor="#dfeaf1"><tr><TD align="center" valign="top" style="padding-left:20px;padding-top:10px;"><div align="left">当前位置: <a href="homepage.jsp">首页</a> > <a href="trainManage.jsp">车次信息管理</a> > 插入车次</div><br /><br /><form action="/TrainDatabase/servlet/InsertTrainAction" method="post"><table border="1" bordercolor="#12A0F5" align=center> <tr><td>火车车次:</td><td><input type="text" id="trainid" name="trainid" style='font-size:18px' width=200/></td></tr><tr><td>出发地:</td><td><input type="text" id="start" name="start" style='font-size:18px' width=200/></td></tr><tr><td>到达地:</td><td><input type="text" id="end" name="end" style='font-size:18px'/></td></tr><tr><td>行车时间:</td><td><input type="text" id="time" name="time" style='font-size:18px'/></td></tr><tr><td>硬座票价:</td><td><input type="text" id="yzprice" name="yzprice" style='font-size:18px'/></td></tr><tr><td>软座票价:</td><td><input type="text" id="rzprice" name="rzprice" style='font-size:18px'/></td></tr><tr><td>硬卧票价:</td><td><input type="text" id="ywprice" name="ywprice" style='font-size:18px'/></td></tr><tr><td>软卧票价:</td><td><input type="text" id="rwprice" name="rwprice" style='font-size:18px'/></td></tr><tr><td>车辆路线:</td><td><textarea id="root" name="root" rows="5" style="width:300px;font-size:18px"></textarea> </td></tr><tr><td colspan=2 align=center><input type="submit" name="Submit" value="提交" style='font-size:18px' width=200/></td></tr></table></form><br /><br />                                              </TD></tr></table></td></tr><tr><td height="20"></td></tr></table></div><div class="div"><!-- 底部版权所有界面 --><TABLE class=wrapper border=0 cellSpacing=0 cellPadding=0 width="100%" align=center><TBODY><TR><TD style="LINE-HEIGHT: 100%" align="center"> <HR style="WIDTH: 96%; HEIGHT: 4px; COLOR: #02457c"><font size="2"> <SCRIPT language=javascript src=""></SCRIPT><!-- target=_blank开启新的网页 --><BR><A href="aboutme.jsp">关于我们</A> | <A href="wzsm.jsp" >网站声明</A> <BR>版权所有&copy;2014-2015 北京邮电大学 Eastmount<BR>京ICP备10009636号 </font></TD></TR></TBODY></TABLE></div></div></body>
</html>

该方法不同于前面的，它是通过Servlet实现的。主要是在采用JSP调用DAO中插入操作总是失败，其流程如下：
1.点击"插入车次"通过超链接到trainManageInsert.jsp，然后通过表单POST提交到Java文件servlet；
<form action="/TrainDatabase/servlet/InsertTrainAction" method="post">
2.在InsertTrainAction.java中通过doPost方法获取提交的表单参数，再调用TrainManageDAO.insert(train)插入数据。最后通过response.sendRedirect重定向到管理页面。
注意：在插入过程中我也是采用"'"+ name +"'"的方式，而不是?来添加参数，否则总报错，详见代码trainManageDAO.java函数insert(TrainManage train)。

六. 删除操作

运行效果如下图所示，点击删除后弹出提示框“确定”后删除：

同时在删除后，通过JavaScript实现5秒后返回管理界面的效果。(因为在PHP网站中我常用这个功能，觉得有意思在JSP中就加入了该功能)

在WebRoot下创建trainManageDelete.jsp文件实现删除操作，代码如下：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session = "true" %>
<jsp:directive.page import="DAO.TrainManageDAO"/>
<jsp:directive.page import="bean.TrainManage"/>
<jsp:directive.page import="java.util.List"/>
<%String action = request.getParameter("action");String id = request.getParameter("id");if(id == null || id==""){    out.println("没有选中删除的车次");  return;    }if("del".equals(action)){int isDelete = TrainManageDAO.delete(id);  request.setAttribute("isDelete", isDelete);  }
%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>火车卡订票系统管理系统</title></head><body><div align="center"><div class="trainCSS"><table width="1024"  height="150" cellpadding="0" cellspacing="0"><tr><td colspan="2"><img src="./image/logo.jpg" alt="logo" width="1024" height="149">       </td></tr>      <tr><td width="205"  bgcolor="#b7d7ec"><p align="center"><script language=JavaScript>today=new Date();function initArray(){this.length=initArray.arguments.length;for(var i=0;i<this.length;i++)this[i+1]=initArray.arguments[i];  }var d=new initArray("星期日","星期一","星期二","星期三","星期四",   "星期五","星期六");document.write("<font color=##ff0000 style='font-size:12pt;font-family: 宋体'> ",today.getYear()+1900,"年",today.getMonth()+1,"月",today.getDate(),"日    ",d[today.getDay()+1],"</font>" );</script> </p> </td> <td width="819" bgcolor="#b7d7ec"><marquee  direction="left" οnmοuseοver=this.stop() οnmοuseοut=this.start() scrollAmount=3 scrollDelay=100><FONT style="FONT-SIZE: 18px"color=blue>欢迎使用火车票订票系统管理系统 ，如有不足，敬请指导！</FONT></marquee></td></tr><tr><td height="12"></td></tr></table></div><div class="trainCSS"><table border="0" width="1024" cellpadding="0" cellspacing="0"><tr><td width="130" bgcolor="#dfeaf1" valign="top"><table width="100%" cellpadding="0" cellspacing="0"  border="0"><tr><td height="10"></td></tr><tr><td align="center">  <font size="3" color="blue">管理员：xxx，欢迎您！</font></td></tr><tr><td height="10"></td></tr><tr><td align="center"><p><a href="trainManage.jsp"><img src="data:image/ccxxgl-xz.jpg" width="194" height="37" border="0"></a><td> </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="buyManage.jsp"><img src="data:image/dpgl.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="peopleManage.jsp"><img src="data:image/hygl.jpg" width="194" height="37" border="0"></a></td></tr>                 <tr><td height="10"></td></tr><tr><td align="center"><a href="serverManage.jsp">                                   <img src="data:image/spqktj.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="infoManage.jsp"><img src="data:image/lygl.jpg" width="194" height="37" border="0"></a>                               </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="exitManage.jsp"><img src="data:image/exit.jpg" width="194" height="37" border="0"></a>                                </td></tr></table></td><td><table width="100%" height="350" border="1"  cellpadding="0" cellspacing="0"  bgcolor="#dfeaf1"><tr><TD align="center" valign="top" style="padding-left:20px;padding-top:10px;"><div align="left">当前位置: <a href="homepage.jsp">首页</a> > <a href="trainManage.jsp">车次信息管理</a> > 删除车次</div><br /><br /><table border="2" bordercolor="#12A0F5" width="50%" height="80%"><tr align=center><td><H2 style="COLOR: #880000">删除成功</H2>  <H4>管理员  xxx 成功删除该车次信息<br />系统将在  <input type="text" style='font-size:18px; border:0px; width:20px;'   readonly="true" value="5" id="time">秒后返回火车票系统管理员车次管理界面 </H4>  </td></tr></table><!-- 时间函数 -->  <script language="javascript">  var t = 5;  var time = document.getElementById("time");  function fun()  {  t--;  time.value = t;  if(t<=0)  {  location.href="trainManage.jsp";   }  }  var inter = setInterval("fun()",1000);  </script>  <br /><br />                                             </TD></tr></table></td></tr><tr><td height="20"></td></tr></table></div><div class="div"><!-- 底部版权所有界面 --><TABLE class=wrapper border=0 cellSpacing=0 cellPadding=0 width="100%" align=center><TBODY><TR><TD style="LINE-HEIGHT: 100%" align="center"> <HR style="WIDTH: 96%; HEIGHT: 4px; COLOR: #02457c"><font size="2"> <SCRIPT language=javascript src=""></SCRIPT><!-- target=_blank开启新的网页 --><BR><A href="aboutme.jsp">关于我们</A> | <A href="wzsm.jsp" >网站声明</A> <BR>版权所有&copy;2014-2015 北京邮电大学 Eastmount   <BR>京ICP备10009636号 </font></TD></TR></TBODY></TABLE></div></div></body>
</html>

删除的核心代码如下：
1.在trainManage.jsp中定义删除超链接及提示框：
<a href="trainManageDelete.jsp?action=del&id=${train.trainid}"
οnclick="return confirm('确定删除?')">删除</a>
2.在DAO中trainManageDAO.java文件中定义SQL删除操作：
public static int delete(String id) throws Exception {
String sql = "DELETE FROM TrainManage WHERE trainid = ? ";
return JDBCConnect.executeUpdate(sql, id);
}
3.在trainManageDelete.jsp中获取传递的trainid(火车车次)值并调用该函数实现删除操作：
<%
String action = request.getParameter("action");
String id = request.getParameter("id");
if(id == null || id==""){out.println("没有选中删除的车次");return;}
if("del".equals(action)){
int isDelete = TrainManageDAO.delete(id);
request.setAttribute("isDelete", isDelete);
}
%>

七. 更新操作及Servlet

具体流程是：首先点击修改，通过超链传递trainid（火车车次）到修改界面，然后通过调用trainManageDAO.java中find查找该车次的所有信息并显示。再通过提交POST及Servlet到UpdateTrainAction.java中，在doPost方法中调用DAO中update(TrainMManage)实现更新。其中运行结果如下图所示：

该方法与插入数据的思路类似，都是通过Servlet实现。其中WebRoot文件夹下创建trainManageUpdate.jsp。其中车次是只读的。

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session = "true" %>
<jsp:directive.page import="DAO.TrainManageDAO"/>
<jsp:directive.page import="bean.TrainManage"/>
<jsp:directive.page import="java.util.List"/>
<%String action = request.getParameter("action");String id = request.getParameter("id");TrainManage train = TrainManageDAO.find(id);  request.setAttribute("train", train);
%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>火车卡订票系统管理系统</title></head><body><div align="center"><div class="trainCSS"><table width="1024"  height="150" cellpadding="0" cellspacing="0"><tr><td colspan="2"><img src="./image/logo.jpg" alt="logo" width="1024" height="149">       </td></tr>      <tr><td width="205"  bgcolor="#b7d7ec"><p align="center"><script language=JavaScript>today=new Date();function initArray(){this.length=initArray.arguments.length;for(var i=0;i<this.length;i++)this[i+1]=initArray.arguments[i];  }var d=new initArray("星期日","星期一","星期二","星期三","星期四",   "星期五","星期六");document.write("<font color=##ff0000 style='font-size:12pt;font-family: 宋体'> ",today.getYear()+1900,"年",today.getMonth()+1,"月",today.getDate(),"日    ",d[today.getDay()+1],"</font>" );</script> </p> </td> <td width="819" bgcolor="#b7d7ec"><marquee  direction="left" οnmοuseοver=this.stop() οnmοuseοut=this.start() scrollAmount=3 scrollDelay=100><FONT style="FONT-SIZE: 18px"color=blue>欢迎使用火车票订票系统管理系统 ，如有不足，敬请指导！</FONT></marquee></td></tr><tr><td height="12"></td></tr></table></div><div class="trainCSS"><table border="0" width="1024" cellpadding="0" cellspacing="0"><tr><td width="130" bgcolor="#dfeaf1" valign="top"><table width="100%" cellpadding="0" cellspacing="0"  border="0"><tr><td height="10"></td></tr><tr><td align="center">  <font size="3" color="blue">管理员：xxx，欢迎您！</font></td></tr><tr><td height="10"></td></tr><tr><td align="center"><p><a href="trainManage.jsp"><img src="data:image/ccxxgl-xz.jpg" width="194" height="37" border="0"></a><td> </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="buyManage.jsp"><img src="data:image/dpgl.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="peopleManage.jsp"><img src="data:image/hygl.jpg" width="194" height="37" border="0"></a></td></tr>                 <tr><td height="10"></td></tr><tr><td align="center"><a href="serverManage.jsp">                                   <img src="data:image/spqktj.jpg" width="194" height="37" border="0"></a></td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="infoManage.jsp"><img src="data:image/lygl.jpg" width="194" height="37" border="0"></a>                               </td></tr><tr><td height="10"></td></tr><tr><td align="center"><a href="exitManage.jsp"><img src="data:image/exit.jpg" width="194" height="37" border="0"></a>                                </td></tr></table></td><td><table width="100%" height="350" border="1"  cellpadding="0" cellspacing="0"  bgcolor="#dfeaf1"><tr><TD align="center" valign="top" style="padding-left:20px;padding-top:10px;"><div align="left">当前位置: <a href="homepage.jsp">首页</a> > <a href="trainManage.jsp">车次信息管理</a> > 插入车次</div><br /><br /><H2 style="COLOR: #880000">修改车次信息</H2> <form action="/TrainDatabase/servlet/UpdateTrainAction" method="post">  <table border="1" bordercolor="#12A0F5" align=center> <tr><td>火车车次:</td><td><input type="text" id="trainid" name="trainid" value=${train.trainid} style='font-size:18px' width=200 readonly="true""/></td></tr><tr><td>出发地:</td><td><input type="text" id="start" name="start" value=${train.start} style='font-size:18px' width=200/></td></tr><tr><td>到达地:</td><td><input type="text" id="end" name="end" value=${train.end} style='font-size:18px'/></td></tr><tr><td>行车时间:</td><td><input type="text" id="time" name="time" value=${train.time} style='font-size:18px'/></td></tr><tr><td>硬座票价:</td><td><input type="text" id="yzprice" name="yzprice" value=${train.yzprice} style='font-size:18px'/></td></tr><tr><td>软座票价:</td><td><input type="text" id="rzprice" name="rzprice" value=${train.rzprice} style='font-size:18px'/></td></tr><tr><td>硬卧票价:</td><td><input type="text" id="ywprice" name="ywprice" value=${train.ywprice} style='font-size:18px'/></td></tr><tr><td>软卧票价:</td><td><input type="text" id="rwprice" name="rwprice" value=${train.rwprice} style='font-size:18px'/></td></tr><tr><td>车辆路线:</td><td><textarea id="root" name="root" rows="5" style="width:300px;font-size:18px">${train.root}</textarea>  </td></tr><tr><td colspan=2 align=center><input type="submit" name="Submit" value="提交" style='font-size:18px' width=200/></td></tr></table></form><br /><br />                                                </TD></tr></table></td></tr><tr><td height="20"></td></tr></table></div><div class="div"><!-- 底部版权所有界面 --><TABLE class=wrapper border=0 cellSpacing=0 cellPadding=0 width="100%" align=center><TBODY><TR><TD style="LINE-HEIGHT: 100%" align="center"> <HR style="WIDTH: 96%; HEIGHT: 4px; COLOR: #02457c"><font size="2"> <SCRIPT language=javascript src=""></SCRIPT><!-- target=_blank开启新的网页 --><BR><A href="aboutme.jsp">关于我们</A> | <A href="wzsm.jsp" >网站声明</A> <BR>版权所有&copy;2014-2015 北京邮电大学 Eastmount   <BR>京ICP备10009636号 </font></TD></TR></TBODY></TABLE></div></div></body>
</html>

然后再src/servlet中创建Servlet类，即UpdateTrainAction.java文件。代码如下：

package servlet;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import DAO.TrainManageDAO;
import bean.TrainManage;public class UpdateTrainAction extends HttpServlet {public UpdateTrainAction() {super();}public void destroy() {super.destroy(); // Just puts "destroy" string in log// Put your code here}//The doGet method of the servlet.public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html");PrintWriter out = response.getWriter();out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");out.println("<HTML>");out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");out.println("  <BODY>");out.print("    This is ");out.print(this.getClass());out.println(", using the GET method");out.println("  </BODY>");out.println("</HTML>");out.flush();out.close();}//The doPost method of the servletpublic void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setCharacterEncoding("UTF-8"); //设置输出编码  request.setCharacterEncoding("UTF-8");  try {//更新数据库String m_trainid = request.getParameter("trainid");String m_start = request.getParameter("start");String m_end = request.getParameter("end");String m_time = request.getParameter("time");String m_yz = request.getParameter("yzprice");Float m_yzprice = Float.parseFloat(m_yz);String m_rz = request.getParameter("rzprice");Float m_rzprice = Float.parseFloat(m_rz);String m_yw = request.getParameter("ywprice");Float m_ywprice = Float.parseFloat(m_yw);String m_rw = request.getParameter("rwprice");Float m_rwprice = Float.parseFloat(m_rw);String m_root = request.getParameter("root");TrainManage train = new TrainManage();train.setTrainid(m_trainid);train.setStart(m_start);train.setEnd(m_end);train.setTime(m_time);train.setYzprice(m_yzprice);train.setRzprice(m_rzprice);train.setYwprice(m_ywprice);train.setRwprice(m_rwprice);train.setRoot(m_root);int success  = TrainManageDAO.update(train);  request.setAttribute("success", success);  //设置全路径 否则trainManage.jsp跳转到servlet/trainManage.jsp路径下不存在response.sendRedirect("http://localhost:8080/TrainDatabase/trainManage.jsp");  } catch(Exception e) {System.out.println("错误："+e.getMessage());  response.sendRedirect("http://localhost:8080/TrainDatabase/trainManage.jsp");  }}public void init() throws ServletException {// Put your code here}}

你可能发现，update函数只修改了start和end，其它你可以自己添加，方法类似。同时如果参数过多建议使用下面的方法替代：

public static int update(TrainManage train) throws Exception {/*** String sql = "UPDATE TrainManage SET start = ?, end = ? WHERE trainid = ? ";* return JDBCConnect.executeUpdate(sql, train.getStart(), train.getEnd(), train.getTrainid());*/String sql = "UPDATE TrainManage SET start = '"+ train.getStart() +"', end = '" + train.getEnd() + "' WHERE trainid = '" + train.getTrainid() +"';";System.out.println(sql);return JDBCConnect.executeUpdate(sql);
}

还有一个查看详情就不介绍了，参看源代码吧~

八. 总结

最后文章就不总结了，因为每步都讲得非常清楚，无论是步骤、思想，还是源代码截图。作者真的很用心的写这篇文章，从晚上8点写到了凌晨5点，中间打了两把dota2。一方面由于我也认为这些都非常重要又基础，另一方面为哪些初学者做Java网站的。
最后希望文章对你有所帮助！如果文章有错误或不足之处，还请海涵~真的有点累了睡了。有时候想想值不值得这样写文章，心安虽好但对身体不好。

（By:Eastmount 2015-5-24 凌晨5点 http://blog.csdn.net/eastmount/）