servlet ---- 简单案例
2024-06-11 16:06:09
index.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>学生管理系首页</title>
</head>
<body>
<a href="/addStudent.html">添加学生</a>
<a href="/listStudentServlet">查看学生</a>
</body>
</html>
addStudent.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>添加学生</title>
</head>
<body><form action="/addStudentServlet" method="get" autocomplete="off">学生姓名：<input type="text" name="username"> <br>学生年龄：<input type="number" name="age"> <br>学生成绩：<input type="number" name="score"> <br><button type="submit">保存</button></form>
</body>
</html>Student
package com.example.domain;public class Student {private String username;private int age;private int score;public Student() {}public Student(String username, int age, int score) {this.username = username;this.age = age;this.score = score;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public int getScore() {return score;}public void setScore(int score) {this.score = score;}
}addStudentServlet
package com.example.servlet;import com.example.domain.Student;
import org.apache.commons.beanutils.BeanUtils;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;@WebServlet(name = "addStudentServlet", value = "/addStudentServlet")
public class addStudentServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取表单中的数据Student stu = new Student();Map<String, String[]> map = request.getParameterMap();try {BeanUtils.populate(stu,map);} catch (Exception e) {e.printStackTrace();}//保存到文件BufferedWriter bw = new BufferedWriter(new FileWriter(getServletContext().getRealPath("/stu.txt"), true));bw.write(stu.getUsername() + "," + stu.getAge() + "," + stu.getScore());bw.newLine();bw.close();//响应response.setContentType("text/html;charset=UTF-8");response.getWriter().write("添加成功，2秒后自动跳转到首页");response.setHeader("Refresh","2;URL=/index.html");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}
}listStudentServlet
package com.example.servlet;import com.example.domain.Student;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;@WebServlet(name = "listStudentServlet", value = "/listStudentServlet")
public class listStudentServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//创建字符输入流对象，关联读取的文件BufferedReader br = new BufferedReader(new FileReader(getServletContext().getRealPath("/stu.txt")));//创建集合对象，用于保存Student对象ArrayList<Student> list = new ArrayList<>();//循环读取文件中的数据，将数据封装到Student对象中。String line;while ((line = br.readLine()) != null){Student stu = new Student();String[] arr = line.split(",");stu.setUsername(arr[0]);stu.setAge(Integer.parseInt(arr[1]));stu.setScore(Integer.parseInt(arr[2]));list.add(stu);}//响应response.setContentType("text/html;charset=UTF-8");PrintWriter pw = response.getWriter();for (Student s : list){pw.write(s.getUsername() + "," + s.getAge() + "," + s.getScore());pw.write("<br>");}br.close();}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}
}
项目目录结构
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>学生管理系统首页</title>
</head>
<body><%--获取会话域中的数据如果获取到了则显示添加和查看功能的超链接如果没获取到则显示登录功能的超链接--%><% Object username = session.getAttribute("username");if (username == null) {%><a href="/stu/login.jsp">请登录</a><%} else {%><a href="/addStudent.jsp">添加学生</a><a href="/listStudentServlet">查看学生</a><%}%>
</body>
</html>login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>学生登录</title>
</head>
<body>
<form action="/LoginStudentServlet" method="get" autocomplete="off">姓名：<input type="text" name="username"> <br>密码：<input type="password" name="password"> <br><button type="submit">登录</button>
</form>
</body>
</html>LoginStudentServlet
package com.example.servlet;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;@WebServlet(name = "LoginStudentServlet", value = "/LoginStudentServlet")
public class LoginStudentServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.获取用户名和密码String username = request.getParameter("username");String password = request.getParameter("password");//2.判断用户名if(username == null || "".equals(username)) {//2.1用户名为空 重定向到登录页面response.sendRedirect("/stu/login.jsp");return;}//2.2用户名不为空 将用户名存入会话域中request.getSession().setAttribute("username",username);//3.重定向到首页index.jspresponse.sendRedirect("/index.jsp");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}
}1.在 web 目录下创建一个 addStudent.jsp，实现添加学生的表单项。
2.创建 AddStudentServlet，获取学生信息并保存到文件中。
3.通过定时刷新功能 2 秒后跳转到首页。
addStudent.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>添加学生</title>
</head>
<body>
<form action="/addStudentServlet" method="get" autocomplete="off">学生姓名：<input type="text" name="username"> <br>学生年龄：<input type="number" name="age"> <br>学生成绩：<input type="number" name="score"> <br><button type="submit">保存</button>
</form>
</body>
</html>Student.java
package com.example.domain;public class Student {private String username;private int age;private int score;public Student() {}public Student(String username, int age, int score) {this.username = username;this.age = age;this.score = score;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public int getScore() {return score;}public void setScore(int score) {this.score = score;}
}addStudentServlet
package com.example.servlet;import com.example.domain.Student;
import org.apache.commons.beanutils.BeanUtils;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;@WebServlet(name = "addStudentServlet", value = "/addStudentServlet")
public class addStudentServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取表单中的数据Student stu = new Student();Map<String, String[]> map = request.getParameterMap();try {BeanUtils.populate(stu,map);} catch (Exception e) {e.printStackTrace();}//保存到文件BufferedWriter bw = new BufferedWriter(new FileWriter(getServletContext().getRealPath("/stu.txt"), true));bw.write(stu.getUsername() + "," + stu.getAge() + "," + stu.getScore());bw.newLine();bw.close();//响应response.setContentType("text/html;charset=UTF-8");response.getWriter().write("添加成功，2秒后自动跳转到首页");response.setHeader("Refresh","2;URL=/index.jsp");}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}
}1.创建 ListStudentServlet，读取文件中的学生信息到集合中。
2.将集合添加到会话域中。
3.重定向到 listStudent.jsp 页面上。
4.在 web 目录下创建一个 listStudent.jsp。
5.定义表格标签。在表格中获取会话域的集合数据，将数据显示在页面上。
listStudent.jsp
<%@ page import="com.itheima.bean.Student" %>
<%@ page import="java.util.ArrayList" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>查看学生</title>
</head>
<body><table width="600px" border="1px"><tr><th>学生姓名</th><th>学生年龄</th><th>学生成绩</th></tr><% ArrayList<Student> students = (ArrayList<Student>) session.getAttribute("students");for(Student stu : students) {%><tr align="center"><td><%=stu.getUsername()%></td><td><%=stu.getAge()%></td><td><%=stu.getScore()%></td></tr><%}%></table>
</body>
</html>ListStudentServlet
package com.example.servlet;import com.example.domain.Student;import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;@WebServlet(name = "listStudentServlet", value = "/listStudentServlet")
public class listStudentServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//创建字符输入流对象，关联读取的文件BufferedReader br = new BufferedReader(new FileReader(getServletContext().getRealPath("/stu.txt")));//创建集合对象，用于保存Student对象ArrayList<Student> list = new ArrayList<>();//循环读取文件中的数据，将数据封装到Student对象中。String line;while ((line = br.readLine()) != null){Student stu = new Student();String[] arr = line.split(",");stu.setUsername(arr[0]);stu.setAge(Integer.parseInt(arr[1]));stu.setScore(Integer.parseInt(arr[2]));list.add(stu);}//响应response.setContentType("text/html;charset=UTF-8");PrintWriter pw = response.getWriter();for (Student s : list){pw.write(s.getUsername() + "," + s.getAge() + "," + s.getScore());pw.write("<br>");}//4.将集合对象存入会话域中request.getSession().setAttribute("students",list);//5.重定向到学生列表页面response.sendRedirect("/stu/listStudent.jsp");br.close();}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}
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