java socket 實現增刪改查 + 在線答題小案例

實現效果

（1）在client端可以實現對數據庫的操作（Select，Insert，Update，Delete）
（2）數據庫中創建一個考試表和學生表，考試表中問題是四項選擇題（10道以上），client端做題，成績存入學生表
（3）實現多個Client程序對server端的訪問 Hint：Java程序中會使用多個class，server端使用thread監聽多個client 。

一、創建數據庫demo，數據表student、question。
其中student表存儲了學生的姓名以及成績記錄、question表中存儲了單項選擇題的有關內容。

二、創建Student、Question 兩個實體類
包含屬性，Getter,Setter方法
Student.java

package com.jxnu.demo;

/**
 * @author xiao
 */
public class Student {
    //主鍵ID
    private Integer id;
    //用戶名
    private String username;
    //分數
    private String grade;
    //生日

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", grade=" + grade +
                '}';
    }
}

Question.java

package com.jxnu.demo;

/**
 * @author xiao
 */
public class Question {

    private Integer id;

    private String Content;

    private String OptionA;

    private String OptionB;

    private String OptionC;

    private String OptionD;

    private String answer;

    private String grade;

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getContent() {
        return Content;
    }

    public void setContent(String content) {
        Content = content;
    }

    public String getOptionA() {
        return OptionA;
    }

    public void setOptionA(String optionA) {
        OptionA = optionA;
    }

    public String getOptionB() {
        return OptionB;
    }

    public void setOptionB(String optionB) {
        OptionB = optionB;
    }

    public String getOptionC() {
        return OptionC;
    }

    public void setOptionC(String optionC) {
        OptionC = optionC;
    }

    public String getOptionD() {
        return OptionD;
    }

    public void setOptionD(String optionD) {
        OptionD = optionD;
    }

    public String getAnswer() {
        return answer;
    }

    public void setAnswer(String answer) {
        this.answer = answer;
    }

    @Override
    public String toString() {
        return "Question{" +
                "id=" + id +
                ", Content='" + Content + '\'' +
                ", OptionA='" + OptionA + '\'' +
                ", OptionB='" + OptionB + '\'' +
                ", OptionC='" + OptionC + '\'' +
                ", OptionD='" + OptionD + '\'' +
                ", answer='" + answer + '\'' +
                ", grade='" + grade + '\'' +
                '}';
    }
}

三、導入jar包，編寫三個與數據庫相關的Java Class，DbManage、
StudentDao和QuestionDao。
其中DbManage有三個方法，initDB()負責打開驅動，兩個close()方法分別關閉有結果集與無結果集。

DBManage.java

package com.jxnu.demo;

import java.sql.*;

/**
 * @author xiao
 */
public class DbManage {

    //打開驅動
    public Connection initDB() {
        Connection conn = null;
        final String DRIVER_NAME = "com.mysql.jdbc.Driver";
        //數據庫連接地址
        final String URL = "jdbc:mysql://localhost:3306/socket?useUnicode=true&characterEncoding=utf-8&useSSL=FALSE&serverTimezone=UTC";
        //用戶名
        final String USER_NAME = "root";
        //密碼
        final String PASSWORD = "";
        try {
            Class.forName(DRIVER_NAME);
            conn = DriverManager.getConnection(URL,USER_NAME,PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

    //關閉無結果集
    public void closeDB(PreparedStatement pstmt, Connection con) {
        try {
            if(pstmt!=null) {
                pstmt.close();
            }
            if(con!=null) {
                con.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    //關閉有結果集
    public void closeDB(ResultSet rs, PreparedStatement pstmt, Connection con) {
        try {
            if(pstmt!=null) {
                pstmt.close();
            }
            if(con!=null) {
                con.close();
            }
            if(rs!=null)
            {
                rs.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

StudentDao.java
StudentDao負責有關學生信息的增刪查改(insert、update、delete、findAll）

package com.jxnu.demo;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * @author xiao
 */
public class StudentDao {

    /**
     * 添加
     * @param student
     * @return
     */
    public boolean insert(Student student) {

        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        String sql = "insert into student(username,grade) VALUES(?,?)";
        boolean res = false;
        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            pstmt.setString(1,student.getUsername());
            pstmt.setString(2,student.getGrade());
            res = (pstmt.executeUpdate() == 1);
        }catch (SQLException e) {
            e.printStackTrace();
        }finally {
            dbmanage.closeDB(pstmt, con);
        }
        return res;
    }

    /**
     * 刪除
     * @param id
     * @return
     */
    public boolean delete(Integer id) {

        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        String sql = "delete from student where id = ?";
        boolean flag = false;

        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            pstmt.setInt(1, id);
            int result = pstmt.executeUpdate();
            if (result > 0) {
                flag = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            dbmanage.closeDB(pstmt, con);
        }
        return flag;
    }

    /**
     * 修改信息
     * @param student
     * @return
     */
    public boolean update(Student student) {
        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        String sql = "update student set username=? where id= ?";
        boolean res = false;
        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            pstmt.setString(1,student.getUsername());
            pstmt.setInt(2,student.getId());
            res = (pstmt.executeUpdate()==1);
        }catch (SQLException e) {
            e.printStackTrace();
            return false;
        }finally {
            dbmanage.closeDB(pstmt, con);
        }
        return res;

    }

    public boolean updateG(Student student) {
        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        String sql = "update student set grade=? where id= ?";
        boolean res = false;
        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            pstmt.setString(1,student.getGrade());
            pstmt.setInt(2,student.getId());
            res = (pstmt.executeUpdate()==1);
        }catch (SQLException e) {
            e.printStackTrace();
            return false;
        }finally {
            dbmanage.closeDB(pstmt, con);
        }
        return res;

    }
    /**
     * 查找所有數據
     * @return
     */
    public List<Student> findAll() {
        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        ResultSet rs = null;
        List<Student> list = new ArrayList<Student>();
        String sql = "select * from student";
        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            rs = pstmt.executeQuery();

            while (rs.next()) {
                Student student = new Student();
                student.setId(rs.getInt("id"));
                student.setUsername(rs.getString("username"));
                student.setGrade(rs.getString("grade"));
                list.add(student);
            }

        }catch (Exception e) {
            e.printStackTrace();
        }finally {
            dbmanage.closeDB(rs,pstmt, con);
        }
        return list;
    }


    /**
     * 根據ID查詢
     * @param id
     * @return
     */
    public List<Student> findById(Integer id) {
        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        ResultSet rs = null;
        //MessageEntity messageEntity = new MessageEntity();
        List<Student> list = new ArrayList<Student>();
        String sql = "select * from student where id=?";
        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            pstmt.setInt(1, id);
            rs = pstmt.executeQuery();

            while(rs.next()){
                Student student = new Student();
                student.setId(rs.getInt("id"));
                student.setUsername(rs.getString("username"));
                student.setGrade(rs.getString("grade"));

                list.add(student);
            }
        }catch (Exception e) {
            e.printStackTrace();
        }finally {
            dbmanage.closeDB(rs,pstmt, con);
        }
        return list;
    }

}

QuestionDao.java
QuestionDao負責有關題目的增刪改查

package com.jxnu.demo;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * @author xiao
 */
public class QuestionDao {

    public List<Question> findAll() {
        DbManage dbmanage = new DbManage();
        Connection con = null;
        PreparedStatement pstmt =null;
        ResultSet rs = null;
        List<Question> list = new ArrayList<Question>();
        String sql = "select * from question";
        try {
            con = dbmanage.initDB();
            pstmt = con.prepareStatement(sql);
            rs = pstmt.executeQuery();

            while (rs.next()) {
                Question question = new Question();
                question.setId(rs.getInt("id"));
                question.setAnswer(rs.getString("answer"));
                question.setContent(rs.getString("content"));
                question.setOptionA(rs.getString("optionA"));
                question.setOptionB(rs.getString("optionB"));
                question.setOptionC(rs.getString("optionC"));
                question.setOptionD(rs.getString("optionD"));
                list.add(question);
            }

        }catch (Exception e) {
            e.printStackTrace();
        }finally {
            dbmanage.closeDB(rs,pstmt, con);
        }
        return list;
    }
}

三、編寫StudentService類，用於處理增刪改查以及答題的邏輯

package com.jxnu.demo;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.List;

/**
 * @author xiao
 */
public class StudentService{

    public void show(Socket socket) throws IOException {
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        StudentDao dao = new StudentDao();
        List<Student> list = dao.findAll();
        out.writeUTF(String.valueOf(list));

    }

    public void insert(Socket socket) throws IOException {
        DataInputStream input = new DataInputStream(socket.getInputStream());
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        out.writeUTF("請輸入新增用戶名");
        String username = input.readUTF();
        out.writeUTF("請輸入用戶成績");
        String grade = input.readUTF();
        StudentDao dao = new StudentDao();
        Student student = new Student();
        student.setUsername(username);
        student.setGrade(grade);
        if(dao.insert(student))
            out.writeUTF("添加成功");
        else
            out.writeUTF("添加失敗");
    }

    public void delete(Socket socket) throws IOException {
        DataInputStream input = new DataInputStream(socket.getInputStream());
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        out.writeUTF("請輸入要刪除的ID號");
        String id = input.readUTF();
        StudentDao dao = new StudentDao();
        if(dao.delete(Integer.valueOf(id)))
            out.writeUTF("刪除成功");
        else
            out.writeUTF("刪除失敗，請確認ID是否存在");
    }

    public void update(Socket socket) throws IOException {
        DataInputStream input = new DataInputStream(socket.getInputStream());
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        out.writeUTF("請輸入要修改的用戶ID號");
        String id = input.readUTF();
        out.writeUTF("請輸入修改後的用戶名");
        String username = input.readUTF();
        StudentDao dao = new StudentDao();
        Student student = new Student();
        student.setId(Integer.valueOf(id));
        student.setUsername(username);
        if(dao.update(student))
            out.writeUTF("更新成功");
        else
            out.writeUTF("更新失敗");
    }

    public void answer(Socket socket) throws IOException {
        DataInputStream input = new DataInputStream(socket.getInputStream());
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        QuestionDao questionDao = new QuestionDao();
        List<Question> questionList = questionDao.findAll();
        Question question = new Question();
        out.writeUTF(String.valueOf(questionList.size()));
        int n = questionList.size();
        //out.writeUTF("請輸入題號");
        int sum = 0;
        String[] answers = new String[20];
        for(int i=0;i<n;i++)
        {
            out.writeUTF("第"+(i+1)+"題"+":  "+questionList.get(i).getContent());
            out.writeUTF("A. " + questionList.get(i).getOptionA() + "\t"
                    + "B. " + questionList.get(i).getOptionB() + "\t"
                    + "C. " + questionList.get(i).getOptionC() + "\t"
                    + "D. " + questionList.get(i).getOptionD());

            answers[i]=input.readUTF();
            System.out.println(answers[i]);
            if(answers[i].equals(questionList.get(i).getAnswer()))
            {
                out.writeUTF("回答正確,+10 分\n");
                sum += 10;
            }
            else
                out.writeUTF("回答錯誤\n");
        }

        String id = input.readUTF();
        out.writeUTF("總成績爲"+sum);
        StudentDao dao = new StudentDao();
        Student student = new Student();
        student.setId(Integer.valueOf(id));
        student.setGrade(String.valueOf(sum));
        if (dao.updateG(student))
            out.writeUTF("成績保存成功");
        else
            out.writeUTF("成績保存失敗");
    }
}

四、編寫Server類。
其中server端使用thread監聽多個client，根據Client端的指令調用不同的方法並執行。收到指令“1”，執行StudentService中的show()方法，查詢出學生表中所有的記錄並返回給Client；收到指令“2”，執行StudentService中的insert()方法，獲取客戶端傳來的姓名與成績並插入student表中。收到指令“3”，執行update()方法，可以實現根據client端傳來的ID號和新姓名實現修改姓名的功能;收到指令“4”，執行delete()方法，可以根據Client端傳來的ID號實現刪除學生記錄的功能；收到指令“5”，實現答題功能，用戶每回答一個題目，Server端判斷正誤並將結果返回給Client端，最後計算出總成績存入student表；收到指令“0”，Client端將斷開連接。

package com.jxnu.demo;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.List;


/**
 * @author xiao
 */
public class Server {
    public static final int PORT = 12345;//監聽的端口號

    public static void main(String[] args) {
        System.out.println("服務器啓動...\n");
        Server server = new Server();
        server.init();
    }

    public void init() {
        try {
            ServerSocket serverSocket = new ServerSocket(PORT);
            while (true) {
                // 一旦有堵塞, 則表示服務器與客戶端獲得了連接
                Socket client = serverSocket.accept();
                // 處理這次連接
                new HandlerThread(client);
            }
        } catch (Exception e) {
            System.out.println("服務器異常: " + e.getMessage());
        }
    }

    public static class HandlerThread implements Runnable {
        private Socket socket;
        public HandlerThread(Socket client) {
            socket = client;
            new Thread(this).start();
        }

        public void run() {
            try {
                // 讀取客戶端數據
                DataInputStream input = new DataInputStream(socket.getInputStream());
                String clientInputStr = input.readUTF();//這裏要注意和客戶端輸出流的寫方法對應,否則會拋 EOFException
                // 處理客戶端數據
                System.out.println("客戶端:" + clientInputStr);
                // 向客戶端回覆信息
                DataOutputStream out = new DataOutputStream(socket.getOutputStream());
                action(clientInputStr,socket);
                out.close();
                input.close();
            } catch (Exception e) {
                System.out.println("服務器 run 異常: " + e.getMessage());
            } finally {
                if (socket != null) {
                    try {
                        socket.close();
                    } catch (Exception e) {
                        socket = null;
                        System.out.println("服務端 finally 異常:" + e.getMessage());
                    }
                }
            }
        }

        public void action(String clientInputStr,Socket socket) throws IOException {
            DataOutputStream out = new DataOutputStream(socket.getOutputStream());
            StudentService studentService = new StudentService();
            switch (clientInputStr)
            {
                case "1":
                    studentService.show(socket);
                    break;

                case "2":
                    studentService.insert(socket);
                    break;

                case "3":
                    studentService.delete(socket);
                    break;

                case "4":
                    studentService.update(socket);
                    break;

                case "5":
                    studentService.answer(socket);
                    break;

                case "0":
                    out.writeUTF("OK");
                    break;
                default:
                    out.writeUTF("輸入指令有誤，請重新輸入");
            }
        }
    }
}

六、編寫Client類

package com.jxnu.demo;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;

/**
 * @author xiao
 */
public class Client {
    public static final String IP_ADDR = "192.168.19.133";//服務器地址
    public static final int PORT = 12345;//服務器端口號

    public static void main(String[] args) {
        System.out.println("客戶端啓動...");
        System.out.print("【提示】 1 表示查看所有學生信息, 2 表示添加學生信息, 3 表示刪除學生信息, 4表示修改學生信息, 5表示做題, 0表示結束\n ");
        while (true) {
            Socket socket = null;
            try {
                //創建一個流套接字並將其連接到指定主機上的指定端口號
                socket = new Socket(IP_ADDR, PORT);

                //讀取服務器端數據
                DataInputStream input = new DataInputStream(socket.getInputStream());
                //向服務器端發送數據
                DataOutputStream out = new DataOutputStream(socket.getOutputStream());
                System.out.println("請輸入指令: \t");
                String str = new BufferedReader(new InputStreamReader(System.in)).readLine();
                out.writeUTF(str);

                String ret = input.readUTF();
                System.out.println("服務器端: " + ret);

                if("請輸入要刪除的ID號".equals(ret)) {
                    String id = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    out.writeUTF(id);
                    String result = input.readUTF();
                    System.out.println(result);
                }
                if("請輸入要修改的用戶ID號".equals(ret)) {
                    String id = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    out.writeUTF(id);
                    System.out.println("服務器端: "+input.readUTF());
                    String username = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    out.writeUTF(username);
                    String result = input.readUTF();
                    System.out.println(result);
                }
                if("請輸入新增用戶名".equals(ret)) {
                    String username = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    out.writeUTF(username);
                    System.out.println("服務端: " + input.readUTF());
                    String grade = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    out.writeUTF(grade);
                    String result = input.readUTF();
                    System.out.println(result);
                }
                // 如接收到 "OK" 則斷開連接
                if ("OK".equals(ret)) {
                    System.out.println("客戶端將關閉連接");
                    Thread.sleep(500);
                    break;
                }
                if (ret.length() <=3 ) {

                    Integer n = Integer.valueOf(ret);
                    System.out.println("總共" + n + "道題,每題10分，總分100分");
                    for(int i=0;i<n;i++) {
                        System.out.println(input.readUTF());
                        System.out.println(input.readUTF());
                        System.out.println("請輸入答案: ");
                        String answer = new BufferedReader(new InputStreamReader(System.in)).readLine();
                        out.writeUTF(answer);
                        System.out.println(input.readUTF());
                    }
                    System.out.println("請輸入你的用戶ID號");
                    String id = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    out.writeUTF(id);
                    String sum = input.readUTF();
                    System.out.println(sum);
                    String result = input.readUTF();
                    System.out.println(result);

                }

                out.close();
                input.close();
            } catch (Exception e) {
                System.out.println("客戶端異常:" + e.getMessage());
            } finally {
                if (socket != null) {
                    try {
                        socket.close();
                        System.out.println("socket is closed");
                    } catch (IOException e) {
                        socket = null;
                        System.out.println("客戶端 finally 異常:" + e.getMessage());
                    }
                }
            }
        }
    }
}

效果圖
這裏我還弄了點花裏胡哨的顏色，有點好看嘿嘿。

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