Java TCP服务器

Java TCP服务器

Java网络教程 - Java TCP服务器 ServerSocket 类的一个对象表示Java中的TCP服务器套接字。 ServerSocket 对象可以接受来自远程客户端的连接请求。我们可以使用no-args构造函数创建一个未绑定的服务器套接字，并使用其bind()方法将其绑定到本地端口和本地IP地址。例子以下代码显示如何创建服务器套接字：import java.net.InetSocketAddress;

import java.net.ServerSocket;

public class Main {

public static void main(String[] argv) throws Exception {

// Create an unbound server socket

ServerSocket serverSocket = new ServerSocket();

// Create a socket address object
InetSocketAddress endPoint = new InetSocketAddress("localhost", 12900);
// Set the wait queue size to 100
int waitQueueSize = 100;
// Bind the server socket to localhost and at port 12900 with
// a wait queue size of 100
serverSocket.bind(endPoint, waitQueueSize);

}

}

例2您可以通过使用以下任何构造函数在一个步骤中组合create，bind和listen操作。等待队列大小的默认值为50。本地IP地址的缺省值是通配符地址，即服务器计算机的所有IP地址。ServerSocket(int port)

ServerSocket(int port, int waitQueueSize)

ServerSocket(int port, int waitQueueSize, InetAddress bindAddr)

您可以将套接字创建和绑定步骤合并为一个语句。以下代码显示如何在端口12900创建服务器套接字，其中100作为等待队列大小，并在localhost回送地址。ServerSocket serverSocket = new ServerSocket(12900, 100, InetAddress.getByName("localhost"));

要接受远程连接请求，请调用服务器套接字上的 accept()方法。accept()方法调用阻塞执行，直到来自远程客户端的请求到达其等待队列。

The following code calls on ServerSocket will wait for a new remote connection request.

Socket activeSocket = serverSocket.accept();

Socket类包含两个方法 getInputStream()和 getOutputStream()用于读取和写入连接的套接字。BufferedReader br = new BufferedReader(new InputStreamReader(activeSocket.getInputStream()));

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(activeSocket.getOutputStream()));

String s = br.readLine();

bw.write("hello");

bw.flush();

最后，使用套接字的close()方法关闭连接。关闭套接字还会关闭其输入和输出流。activeSocket.close();

以下代码显示如何创建服务器套接字。import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.net.InetAddress;

import java.net.ServerSocket;

import java.net.Socket;

public class Main {

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

ServerSocket serverSocket = new ServerSocket(12900, 100,

InetAddress.getByName("localhost"));

System.out.println("Server started at: " + serverSocket);

while (true) {
  System.out.println("Waiting for a  connection...");
  final Socket activeSocket = serverSocket.accept();
  System.out.println("Received a  connection from  " + activeSocket);
  Runnable runnable = () -> handleClientRequest(activeSocket);
  new Thread(runnable).start(); // start a new thread
}

}

public static void handleClientRequest(Socket socket) {

try{

BufferedReader socketReader = null;

BufferedWriter socketWriter = null;

socketReader = new BufferedReader(new InputStreamReader(

socket.getInputStream()));

socketWriter = new BufferedWriter(new OutputStreamWriter(

socket.getOutputStream()));

  String inMsg = null;
  while ((inMsg = socketReader.readLine()) != null) {
    System.out.println("Received from  client: " + inMsg);
    String outMsg = inMsg;
    socketWriter.write(outMsg);
    socketWriter.write("\n");
    socketWriter.flush();
  }
  socket.close();
}catch(Exception e){
  e.printStackTrace();
}

}

}