树莓派提升计划 Android应用用MiniChatAppApp之AppServer构建

2021SC@SDUSC

一、项目结构

(1)在web 目录下创建META-INF目录，在目录下创建文件context.xml 地址构成

jdbc:mysql://minichat@localhost:3306/mini_chat?serverTimezone=GMT%2B8&amp;useUnicode=true&amp;characterEncoding=utf-8

context.xml:

<?xml version="1.0" encoding="utf-8"?>
<Context reloadable="true"><Resourcename="jdbc/minichat"type="javax.sql.DataSource"maxTotal="100"maxIdle="50"driverClassName="com.mysql.cj.jdbc.Driver"url="jdbc:mysql://minichat@localhost:3306/mini_chat?serverTimezone=GMT%2B8&amp;useUnicode=true&amp;characterEncoding=utf-8"userName="root"password="root"maxWaitMillis="5000"/>
</Context>

第(2)WEB-INF目录下创建目录lib

2.数据库 Dao

所有的实体dao都应该继承于Dao接口

package DB.Base;import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;public interface Dao {static DataSource getDataSource(){DataSource dataSource=null;try{Context context=new InitialContext();dataSource=(DataSource)context.lookup("java:comp/env/jdbc/minichat");}catch (NamingException ne){ne.printStackTrace();}return dataSource;}default Connection getConnection() throws DaoException{DataSource dataSource=getDataSource();Connection connection=null;try{connection=dataSource.getConnection();}catch (SQLException se){se.printStackTrace();}return connection;}
}

DaoException:

package DB.Base;import java.io.Serializable;public class DaoException extends Exception implements Serializable {private static final long serialVersionUID=19192L;private String message;public DaoException(){}public DaoException(String message){this.message=message;}@Overridepublic String getMessage() {return message;}public void setMessage(String message) {this.message = message;}@Overridepublic String toString() {return "DaoException{" +"message='" + message + '\'' +'}';}
}

FriendDao和UserDao都继承dao接口

package DB.Dao;import DB.Base.Dao;
import Model.Response.FriendAddResponse;
import Model.Response.FriendResponse;import java.util.List;public interface FriendDao extends Dao {List<FriendResponse> getFriendsById(String uid);FriendAddResponse addFriend(String uid,String fid);
}

package DB.Dao;import DB.Base.Dao;
import DB.Base.DaoException;
import DB.model.User;
import Model.Response.LoginResponse;public interface UserDao extends Dao {boolean signup(String uid,String uname,String password) throws DaoException;LoginResponse login(String uid,String password);
}

FriendDaoImpl和UserDaoImpl分别实现各自的Dao接口

package DB.Impl;import DB.Base.DaoException;
import DB.Dao.FriendDao;
import Model.Response.FriendAddResponse;
import Model.Response.FriendResponse;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;public class FriendDaoImpl implements FriendDao {@Overridepublic List<FriendResponse> getFriendsById(String uid) {List<FriendResponse> friendResponses=new ArrayList<>();System.out.println(uid);try(Connection connection=getConnection()){PreparedStatement pst=connection.prepareStatement("select * from friend where uid=?");pst.setString(1,uid);ResultSet rst=pst.executeQuery();while (rst.next()){friendResponses.add(new FriendResponse(1,null,rst.getString("fid"),uid,rst.getString("f_name"),rst.getString("nick_name")));}} catch (SQLException sqlException) {sqlException.printStackTrace();} catch (DaoException e) {e.printStackTrace();}return friendResponses;}@Overridepublic FriendAddResponse addFriend(String uid, String fid) {FriendAddResponse response=new FriendAddResponse(-1,null);try(Connection connection=getConnection()){String f_name=null;String uname=null;PreparedStatement pst=connection.prepareStatement("select uname from user where uid=?");pst.setString(1,fid);ResultSet rst=pst.executeQuery();if(rst.next()){f_name=rst.getString("uname");}else {response.setMessage("id 不存在");}pst.setString(1,uid);rst=pst.executeQuery();if(rst.next()){uname=rst.getString("uname");}else {response.setMessage("id 不存在");}if(f_name!=null&&uname!=null){PreparedStatement pst2=connection.prepareStatement("insert into friend(fid,uid,f_name) VALUES (?,?,?)");pst2.setString(1,fid);pst2.setString(2,uid);pst2.setString(3,f_name);int result0=pst2.executeUpdate();if(result0>0){pst2.setString(1,uid);pst2.setString(2,fid);pst2.setString(3,uname);int result1=pst2.executeUpdate();if(result1>0){response.setCode(1);response.setMessage("add friend success");response.setId(fid);response.setName(f_name);}else {response.setMessage("已添加");}}else {response.setMessage("已添加");}}} catch (SQLException | DaoException sqlException) {sqlException.printStackTrace();}return response;}
}

package DB.Impl;import DB.Base.Dao;
import DB.Base.DaoException;
import DB.Dao.UserDao;
import Model.Response.LoginResponse;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;public class UserDaoImpl implements UserDao {@Overridepublic boolean signup(String uid, String uname, String password) throws DaoException{try(Connection connection=getConnection()){PreparedStatement pst=connection.prepareStatement("insert into user(uid,uname,password) values (?,?,?)");pst.setString(1,uid);pst.setString(2,uname);pst.setString(3,password);int result=pst.executeUpdate();return result>0;} catch (SQLException sqlException) {sqlException.printStackTrace();} catch (DaoException e) {e.printStackTrace();}return false;}@Overridepublic LoginResponse login(String uid, String password)  {System.out.println(uid+password);LoginResponse loginResponse=new LoginResponse();loginResponse.setCode(-1);try(Connection connection=getConnection()){PreparedStatement pst=connection.prepareStatement("select * from user where uid=?");pst.setString(1,uid);ResultSet rst=pst.executeQuery();while (rst.next()){if(rst.getString("password").equals(password)){loginResponse.setCode(1);loginResponse.setMessage("login ok");loginResponse.setUid(uid);loginResponse.setName(rst.getString("uname"));}else {loginResponse.setCode(-1);loginResponse.setMessage("login in password failed");}}}catch (DaoException daoException){daoException.printStackTrace();loginResponse.setMessage("login in dao failed");} catch (SQLException sqlException) {sqlException.printStackTrace();loginResponse.setMessage("login in sql failed");}return loginResponse;}
}

消息以及请求，相应的实现：

消息：message：

package Model.Base;import java.io.Serializable;public class Message implements Serializable {//@param: code 1成功 0未初始化 -1错误//@param: message 错误信息提示或其他信息private int code;private String message;public Message() {code=0;message=null;}public Message(int code, String message) {this.code = code;this.message = message;}public int getCode() {return code;}public void setCode(int code) {this.code = code;}public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}
}

各种请求：request：这里以FriendAddRequest为例：

package Model.Request;public class FriendAddRequest {String uid;String f_id;public FriendAddRequest(String uid, String f_id) {this.uid = uid;this.f_id = f_id;}public String getUid() {return uid;}public void setUid(String uid) {this.uid = uid;}public String getF_id() {return f_id;}public void setF_id(String f_id) {this.f_id = f_id;}
}

各种响应：Response这里以FriendAddResponse为例

package Model.Response;import Model.Base.Message;public class FriendAddResponse extends Message {String id;String name;public FriendAddResponse() {}public FriendAddResponse(int code, String message) {super(code, message);}public FriendAddResponse(int code, String message, String id, String name) {super(code, message);this.id = id;this.name = name;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

三、servelet

最后是各种servelet,以FriendAddServlet为例

package Servlet;import DB.Dao.FriendDao;
import DB.Impl.FriendDaoImpl;
import Model.Request.FriendAddRequest;
import Model.Response.FriendAddResponse;
import com.google.gson.Gson;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;@WebServlet(name = "FriendAddServlet",urlPatterns ={"/addFriend"})
public class FriendAddServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {FriendAddRequest friendAddRequest=new Gson().fromJson(request.getReader(),FriendAddRequest.class);FriendAddResponse friendAddResponse=new FriendDaoImpl().addFriend(friendAddRequest.getUid(),friendAddRequest.getF_id());String rp=new Gson().toJson(friendAddResponse);response.setContentType("txt/html;charset=utf-8");PrintWriter writer=response.getWriter();writer.print(rp);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}
}

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