java案例-服务端与客户端（传输对象）

需求

代码

• SysUser 用户类
• Operation 操作类
• Client 客户端
• Server 服务端
• ServerReaderThread 服务端线程类

SysUser 用户类

• 需要实现Serializable 方便序列化，传输对象

public class SysUser implements Serializable {
    private String username;
    private String password;

    public SysUser() {
    }

    public SysUser(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return this.username;
    }

    public String getPassword() {
        return this.password;
    }

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

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "SysUser{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

操作类

操作方法和被操作的用户

public class Operation implements Serializable {
    private String operation;
    private SysUser sysUser;

    public Operation() {
    }

    public Operation(String operation, SysUser sysUser) {
        this.operation = operation;
        this.sysUser = sysUser;
    }

    public String getOperation() {
        return this.operation;
    }

    public SysUser getSysUser() {
        return this.sysUser;
    }

    public void setOperation(String operation) {
        this.operation = operation;
    }

    public void setSysUser(SysUser sysUser) {
        this.sysUser = sysUser;
    }

    @Override
    public String toString() {
        return "Operation{" +
                "operation='" + operation + '\'' +
                ", sysUser=" + sysUser +
                '}';
    }
}

客户端

• 本例是一个长连接：一直挂在服务器端，那么服务器端的读取线程中就必须要有一个while 循环 不断读取此长连接的内容
• 如果不使用本例的方法，而是每次都创建新的socket 连接服务器，那么读取线程中就必须要有一个while 循环就是非必要的，因为每次连接只会发送一次，等待服务器端响应之后，需要关闭此socket，这就是短连接

// 该类是一个客户端类
public class Client {

    private static Scanner scanner = new Scanner(System.in);



    public static void main(String[] args) throws IOException {
        start();
    }


    // 该方法是一个启动方法
    public static void start() throws IOException {

        Scanner scanner = new Scanner(System.in);

        Socket socket = new Socket("127.0.0.1",8888);

        // 此处加死循环 是为了让客户端一直运行
        while (true){

            System.out.println("请输入你要进行的操作");
            System.out.println("1.注册");
            System.out.println("2.登录");
            System.out.println("3.退出");
            String i = scanner.next();
            switch (i){
                case "1":
                    System.out.println("注册");
                    register(socket);
                    break;
                case "2":
                    System.out.println("登录");
                    login(socket);
                    break;
                case "3":
                    System.out.println("退出");
                    socket.close();
                    break;
                default:
                    System.out.println("输入错误，请重新输入");
            }
        }
    }

    // 该方法是一个注册方法
    public static void register(Socket socket) throws IOException {

        System.out.println("请输入用户名");
        String username = scanner.next();
        System.out.println("请输入密码");
        String password = scanner.next();
        SysUser sysUser = new SysUser(username,password);
        Operation operation = new Operation("register",sysUser);
        // 获取输出流
        requestAndRespond(socket, operation);

    }

    private static void requestAndRespond(Socket socket, Operation operation) throws IOException {
        OutputStream outputStream = socket.getOutputStream();
        // 封装输出流为对象输出流
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
        // 写出对象
        objectOutputStream.writeObject(operation);
        objectOutputStream.flush();
        // 不要关闭流 否则会关闭socket
        //objectOutputStream.close();

        // 获取响应
        InputStream inputStream = socket.getInputStream();
        DataInputStream dataInputStream = new DataInputStream(inputStream);
        String response = dataInputStream.readUTF();
        System.out.println(response);

    }

    // 该方法是一个登录方法
    public static void login(Socket socket) throws IOException {
        System.out.println("请输入用户名");
        String username = scanner.next();
        System.out.println("请输入密码");
        String password = scanner.next();
        SysUser sysUser = new SysUser(username,password);
        Operation operation = new Operation("login",sysUser);
        // 获取输出流
        requestAndRespond(socket, operation);
    }
}

服务器端

// 该类是一个服务端类
public class Server {

    // 模拟数据库
    public static final File file = new File("test999.txt");

    public static ServerSocket serverSocket;

    //  创建线程池
    public static final ExecutorService pool =  new ThreadPoolExecutor(3, 5, 8, TimeUnit.SECONDS,
            new ArrayBlockingQueue<>(4), Executors.defaultThreadFactory(), new ThreadPoolExecutor.AbortPolicy());

    static {
        try {
            serverSocket = new ServerSocket(8888);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) throws IOException {
        start();

    }

    // 该方法是一个启动方法
    public static void start() throws IOException {
        System.out.println("服务端启动");
        listen();
    }

    public static void listen() throws IOException {
        System.out.println("监听中");


        // 此处加死循环 是为了让服务器已知监听有没有客户端连接
        while (true){
            // 获取客户端的socket
            Socket socket = serverSocket.accept();
            // 使用线程池执行线程
            pool.execute(new ServerReaderThread(socket));
        }
    }

    // 该方法是一个注册方法
    public static void register(SysUser sysUser,Socket socket) throws IOException, ClassNotFoundException {
        System.out.println("注册");
        // 获取数据库中的所有用户
        FileInputStream fileInputStream = new FileInputStream(file);
        if (fileInputStream.available() > 0) {
            ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
            ArrayList<SysUser> sysUsers = (ArrayList<SysUser>) objectInputStream.readObject();
            for (SysUser user : sysUsers) {
                if (user.getUsername().equals(sysUser.getUsername())) {
                    System.out.println("用户名已存在");
                    OutputStream outputStream = socket.getOutputStream();
                    DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
                    dataOutputStream.writeUTF("用户名已存在");
                    dataOutputStream.flush();
//                    dataOutputStream.close();
                    return;
                }
            }
        }


        // 注册用户
        // 将用户写入数据库 追加模式
        FileOutputStream fileOutputStream = new FileOutputStream(file,true);
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
        ArrayList<SysUser> sysUsersRegister = new ArrayList<>();
        sysUsersRegister.add(sysUser);
        objectOutputStream.writeObject(sysUsersRegister);
        System.out.println("注册成功");
        System.out.println(sysUser);
        OutputStream outputStream = socket.getOutputStream();
        DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
        dataOutputStream.writeUTF("注册成功");
        dataOutputStream.flush();
//        dataOutputStream.close();


    }

    // 该方法是一个登录方法
    public static void login(SysUser sysUser,Socket socket) throws IOException, ClassNotFoundException {
        System.out.println("登录");
        // 获取数据库中的所有用户
        FileInputStream fileInputStream = new FileInputStream(file);
        if (fileInputStream.available() > 0) {
            ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
            ArrayList<SysUser> sysUsers = (ArrayList<SysUser>) objectInputStream.readObject();
            for (SysUser user : sysUsers) {
                if (user.getUsername().equals(sysUser.getUsername())&&user.getPassword().equals(sysUser.getPassword())) {
                    System.out.println("登录成功");
                    System.out.println(sysUser);
                    OutputStream outputStream = socket.getOutputStream();
                    DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
                    dataOutputStream.writeUTF("登录成功");
                    dataOutputStream.flush();
//                    dataOutputStream.close();
                }else {
                    System.out.println("用户名或密码错误");
                    OutputStream outputStream = socket.getOutputStream();
                    DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
                    dataOutputStream.writeUTF("用户名或密码错误");
                    dataOutputStream.flush();
//                    dataOutputStream.close();
                }
            }
        }else {
            System.out.println("数据库中没有用户");
            OutputStream outputStream = socket.getOutputStream();
            DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
            dataOutputStream.writeUTF("数据库中没有用户");
            dataOutputStream.flush();
//            dataOutputStream.close();
        }



    }
}

服务器端读取类

• 本例是一个长连接：一直挂在服务器端，那么服务器端的读取线程中就必须要有一个while 循环 不断读取此长连接的内容
• 如果不使用本例的方法，而是每次都创建新的socket 连接服务器，那么读取线程中就必须要有一个while 循环就是非必要的，因为每次连接只会发送一次，等待服务器端响应之后，需要关闭此socket，这就是短连接

ServerReaderThread extends Thread {
    private Socket socket;

    public ServerReaderThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try {
            // 最开始这个地方没有死循环，导致客户端只能发送一次请求
            // 这个地方加入死循环 是为了即使是一个request也能一直获得用户的输入
            // 这个地方如果不加入死循环，那么应该建立短连接
            // 也就是说，客户端发送一个请求，都会建立一个新的socket，服务端处理完这个请求之后，返回给客户端结果，客户端处理完结果之后，关闭socket
            while(true){
                // 获取输入流
                InputStream inputStream = socket.getInputStream();
                // 封装输入流为对象输入流
                ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);

                // 读取对象
                Operation operation = (Operation) objectInputStream.readObject();
                // 获取操作
                String operation1 = operation.getOperation();
                // 获取用户
                SysUser sysUser = operation.getSysUser();
                System.out.println("线程方法");
                switch (operation1) {
                    case "register":
                        register(sysUser,socket);
                        break;
                    case "login":
                        login(sysUser,socket);
                        break;
                    default:
                        break;
                }
            }

        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}