Java socket programming example based on Tcp protocol

This article illustrates the Java socket programming method based on Tcp protocol. Specific analysis is as follows:

The following is a one-to-one communication programming implementation, and we will continue to learn about the implementation of one server listening to multiple clients.

The main steps used here are as follows:

Step 1: create a new socket object with a specific port, such as 4800
Step 2: construct the BufferedReader object with the system input device, which is used to receive the characters entered by the system keyboard
Step 3: construct a PrintWriter with an output stream from a socket object
Step 4: construct the corresponding BufferedReader object by getting the input stream from the socket object, which is used to receive the information sent from the server side

I understand to close the socket: open first then close, socket last close.

The following is the code implementation of the client:

package com.fan.socket;
import java.io.*;

import java.net.Socket;
public class SocketClient {

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

Socket socket=new Socket("127.0.0.1",4800);

System.out.println("client start ...");

//A customer request 
 is issued to port 4800 on the machine
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

//The BufferedReader object 
 is constructed by the system standard input device
PrintWriter write=new PrintWriter(socket.getOutputStream());

//The output stream is obtained from the Socket object and the PrintWriter object 
 is constructed
BufferedReader in=new BufferedReader(new InputStreamReader(socket.getInputStream()));

//The input stream is obtained by the Socket object and the corresponding BufferedReader object 
 is constructed
String readline;

readline=br.readLine(); //Read in a string 
 from system standard input
while(!readline.equals("end")){

//If the string read from the standard input is "end", the loop 
 is stopped
write.println(readline);

//Output the string read from the system standard input to Server2

write.flush();

//Flush the output stream so that the Server receives the string 
 immediately
System.out.println("Client:"+readline);

//Print the read string 
 on the system standard output
System.out.println("Server:"+in.readLine());

//Read a string from the Server and print it to 
 on standard output
readline=br.readLine(); //Read in a string 
 from system standard input
} //Continue the loop 

write.close(); //Close Socket output stream 

in.close(); //Close Socket input stream 

socket.close(); //Close Socket 

}catch(Exception e) {

System.out.println("can not listen to:"+e);//Error, print error message 

}

}
}

Server-side code implementation:

package com.fan.socket;
import java.io.*;

import java.net.ServerSocket;

import java.net.Socket;
public class SocketService {

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

SocketService socketService = new SocketService();

socketService.oneServer();

}
public void oneServer(){

try{

ServerSocket server=null;

try{

server=new ServerSocket(4800);

System.out.println("server start is ok...");

//Create a ServerSocket on port 4800 to listen for customer requests 

}catch(Exception e) {

System.out.println("can not listen to:"+e);

//Error, print error message 

}

Socket socket=null;

try{

socket=server.accept();

//Use accept() to block waiting for a customer request. There is a customer 

//The request arrives, produces a Socket object, and continues with 

}catch(Exception e) {

System.out.println("Error."+e);

//Error, print error message 

}

String line;

BufferedReader in=new BufferedReader(new InputStreamReader(socket.getInputStream()));

//The input stream is obtained by the Socket object and the corresponding BufferedReader object 
 is constructed
PrintWriter writer=new PrintWriter(socket.getOutputStream());

//The output stream is obtained from the Socket object and the PrintWriter object 
 is constructed
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

//The BufferedReader object 
 is constructed by the system standard input device
System.out.println("Client:"+in.readLine());

//Print the string 
 read from the client on standard output
line=br.readLine();

//Reads in a string 
 from standard input
while(!line.equals("end")){

//If the string is "bye", the loop 
 is stopped
writer.println(line);

//Output the string 
 to the client
writer.flush();

//Flush the output stream so that the Client receives the string 
 immediately
System.out.println("Server:"+line);

//Print the read string 
 on the system standard output
System.out.println("Client:"+in.readLine());

//Read a string from the Client and print it to 
 on standard output
line=br.readLine();

//Read in a string 
 from system standard input
} //Continue the loop 

writer.close(); //Close Socket output stream 

in.close(); //Close Socket input stream 

socket.close(); //Close the Socket < br / >
server.close(); //Close the ServerSocket < br / >
}catch(Exception e) {//Error, print error message 

System.out.println("Error."+e);

}

}

}

I hope this article has been helpful to your Java programming.