Detailed explanation of client and server example codes for simulating TCP transmission in Java

This article mainly introduces the relevant information on the client and server examples of simulating TCP transmission in Java. Friends in need can refer to the following

1. Create a client for TCP transmission

1. To establish the Socket service of the TCP client, use the Socket object. It is recommended that the destination be clear as soon as the object is created, that is, the host to be connected;

2. If the connection is established successfully, it means that the data transmission channel has been established. This channel is the Socket stream, which is established by the bottom layer. Since it is a stream, it means that there are both input streams and output streams. If you want to input The stream or output stream object can be obtained through Socket, and can be obtained through getOutputStream() and getInputStream();

3. Use the output stream to write out the data;

4. Close the Socket service.

import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;

public class Client {
  public static void main(String[] args) throws IOException {

    // 1、创建客户端的Socket服务
    Socket socket = new Socket("192.168.1.100", 10002);

    // 2、获取Socket流中输入流
    OutputStream out = socket.getOutputStream();

    // 3、使用输出流将指定的数据写出去
    out.write("TCP is coming !".getBytes());

    // 4、关闭Socket服务
    socket.close();
  }
}

2. Create a server for TCP transmission

1. Establish a Socket service for the TCP server through the ServerSocket object;

2. The server must provide a port to the outside world, otherwise the client cannot connect;

3. Get the connected client object;

4. Through the client object To obtain the Socket stream and read the data sent by the client;

5. Close the resource, close the client, and close the server.

import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
  public static void main(String[] args) throws IOException {

    // 1、创建客户端对象
    ServerSocket ss = new ServerSocket(10002);

    // 2、获取连接过来的客户端对象
    Socket s = ss.accept();

    String ip = s.getInetAddress().getHostAddress();

    // 3、通过Socket对象获取输入流，读取客户端发来的数据
    InputStream in = s.getInputStream();

    byte[] buf = new byte[1024];

    int len = in.read(buf);
    String text = new String(buf, 0, len);
    System.out.println(ip + ":" + text);

  // 4、关闭资源
    s.close();
    ss.close();
  }
}

3. Optimize the client and server of TCP transmission

In this part, we optimize the content of the first two parts to achieve TCP transmission mode Interactive functions between client and server.

/**
*优化TCP传输的客户端
*/
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class ClientUpdate {
  public static void main(String[] args) throws IOException {

    Socket socket = new Socket("192.168.1.100", 10002);

    OutputStream out = socket.getOutputStream();

    out.write("tcp!".getBytes());

    // 读取服务端返回的数据，使用Socket读取流
    InputStream in = socket.getInputStream();
    byte[] buf = new byte[1024];

    int len = in.read(buf);

    String text = new String(buf, 0, len);

    System.out.println(text);

    socket.close();
  }
}

/**
*优化TCP传输的服务端
*/
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerUpdate {
  public static void main(String[] args) throws IOException {

    // 1、创建服务端对象
    ServerSocket ss = new ServerSocket(10002);

    // 2、获取连接过来的客户端对象
    Socket s = ss.accept(); //accept方式为阻塞式方法

    String ip = s.getInetAddress().getHostAddress();

    // 3、通过Socket对象获取输入流，要读取客户端发来的数据
    InputStream in = s.getInputStream();

    byte[] buf = new byte[1024];

    int len = in.read(buf);
    String text = new String(buf, 0, len);
    System.out.println(ip + ":" + text);

    // 使用客户端的Socket对象的输出流给客户端返回数据
    OutputStream out = s.getOutputStream();
    out.write("收到".getBytes());

    s.close();
    ss.close();
  }
}

4. Create an English capitalization conversion server

Apply the relevant properties of TCP (Transmission Control Protocol, Transmission Control Protocol) to create an English capitalization based on TCP transmission Conversion server requires: the client inputs letter data and sends it to the server; the server receives the data and displays it on the console, and converts the data into uppercase letters and returns it to the client; until the client inputs "over", the conversion Finish.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class TransClient {
  public static void main(String[] args) throws IOException {
    /**
     * 思路：创建客户端
     * 1、创建Socket客户端对象
     * 2、获取键盘录入的数据
     * 3、将录入的信息发送给Socket输出流
     * 4、读取服务端的数据并返回的大写数据
     */

    // 1、创建Socket客户端对象
    Socket s = new Socket("192.168.1.100", 10004);

    // 2、获取键盘录入
    BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));

    // 3、Socket输出流
    PrintWriter out = new PrintWriter(s.getOutputStream(), true);

    // 4、Socket输入流，读取服务端的数据并返回的大写数据
    BufferedReader bufIn = new BufferedReader(new InputStreamReader(s.getInputStream()));

    String line = null;

    while ((line = bufr.readLine()) != null) {

      if ("over".equals(line))
        break;
      out.println(line);

      // 读取服务端返回的一行大写数据
      String upperStr = bufIn.readLine();
      System.out.println(upperStr);
    }
    s.close();
  }
}

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