网络编程之TCP协议

TCP通信需要经过创建连接、数据传送、终止连接三个步骤。
TCP通信模型中，在通信开始之前，一定要先建立相关的链接，才能发送数据，类似于生活中，“打电话”

    public static void main(String[] args) throws IOException {
        System.out.println("----我是客户端---------");
        //1.构建我是客户端 Socket(String host, int port)
        Socket client = new Socket("127.0.0.1", 8989);
        //2.基于IO操作
        DataOutputStream os = new DataOutputStream(client.getOutputStream());
        os.writeUTF("哈哈");
        os.flush();

        //3.关闭
        os.close();
        client.close();
    }
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public static void main(String[] args) throws IOException {
        System.out.println("----我是服务端---------");
        //1.构建我是服务端  ServerSocket
        ServerSocket server = new ServerSocket(8989);
        //2.阻塞式监听 Socket accept()
        Socket client = server.accept();
        System.out.println("----一个客户端连接成功---------");
        //3.IO操作
        DataInputStream is = new DataInputStream(client.getInputStream());
        String str = is.readUTF();
        System.out.println(str);
        //4.关闭
        is.close();
        client.close();
        server.close();
    }

 public static void main(String[] args) throws IOException {
        System.out.println("----我是客户端---------");
        //1.构建我是客户端 Socket(String host, int port)
        Socket client = new Socket("127.0.0.1", 8989);
        //2.键盘接收用户名与密码
        BufferedReader rd = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("请输入用户名 : ");
        String username = rd.readLine();
        System.out.println("请输入用户密码 : ");
        String password = rd.readLine();

        //3.基于IO操作
        DataOutputStream os = new DataOutputStream(client.getOutputStream());
        //username=zhangsan&password=123
        os.writeUTF("username="+username+"&password="+password);
        os.flush();

        //3.关闭
        os.close();
        rd.close();
        client.close();
    }
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 public static void main(String[] args) throws IOException {
        System.out.println("----我是服务端---------");
        //1.构建我是服务端  ServerSocket
        ServerSocket server = new ServerSocket(8989);
        //2.阻塞式监听 Socket accept()
        Socket client = server.accept();
        System.out.println("----一个客户端连接成功---------");
        //3.IO操作
        DataInputStream is = new DataInputStream(client.getInputStream());
        String str = is.readUTF();  //username=zhangsan&password=1234    //zhangsan 1234

        String msg = "username="+"zhangsan"+"&password="+"1234";
        if(msg.equals(str)){
            System.out.println("登录成功");
        }else{
            System.out.println("登录失败");
        }

        //4.关闭
        is.close();
        client.close();
        server.close();
    }

public static void main(String[] args) throws IOException {
        System.out.println("----我是客户端---------");
        //1.构建我是客户端 Socket(String host, int port)
        Socket client = new Socket("127.0.0.1", 8989);
        //2.键盘接收用户名与密码
        BufferedReader rd = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("请输入用户名 : ");
        String username = rd.readLine();
        System.out.println("请输入用户密码 : ");
        String password = rd.readLine();

        //3.基于IO操作向服务器发送数据
        DataOutputStream os = new DataOutputStream(client.getOutputStream());
        //username=zhangsan&password=123
        os.writeUTF("username="+username+"&password="+password);
        os.flush();

        //4.基于IO操作接收服务器响应的结果
        DataInputStream is = new DataInputStream(client.getInputStream());
        String result = is.readUTF();
        //5.处理结果
        System.out.println(result);

        //6.关闭
        is.close();
        os.close();
        rd.close();
        client.close();
    }
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public static void main(String[] args) throws IOException {
        System.out.println("----我是服务端---------");
        //1.构建我是服务端  ServerSocket
        ServerSocket server = new ServerSocket(8989);
        //2.阻塞式监听 Socket accept()
        Socket client = server.accept();
        System.out.println("----一个客户端连接成功---------");
        //3.IO操作收客户端数据
        DataInputStream is = new DataInputStream(client.getInputStream());
        String str = is.readUTF();  //username=zhangsan&password=1234    //zhangsan 1234

        //4.处理数据
        String uname = "";
        String upwd = "";
        String[] arr = str.split("&");
        for(String s:arr){
            String[] arr2 = s.split("=");
            if("username".equals(arr2[0])){
                uname = arr2[1];
            }else if("password".equals(arr2[0])){
                upwd = arr2[1];
            }
        }
        //5.IO操作将结果响应给客户端
        DataOutputStream os = new DataOutputStream(client.getOutputStream());
        if("zhangsan".equals(uname) && "1234".equals(upwd)){
            os.writeUTF("登录成功");
        }else{
            os.writeUTF("登录失败");
        }
        os.flush();
        //4.关闭
        os.close();
        is.close();
        client.close();
        server.close();
    }