Java通过 Socket 实现 TCP服务端

Java通过 Socket 实现 TCP服务端

1 java Socket简介

所谓socket 通常也称作”套接字“，用于描述IP地址和端口，是一个通信链的句柄。应用程序通常通过”套接字”向网络发出请求或者应答网络请求。Socket和ServerSocket类库位于Java.NET包中。ServerSocket用于服务器端，Socket是建立网络连接时使用的。在连接成功时，应用程序两端都会产生一个Socket实例，操作这个实例，完成所需的会话。对于一个网络连接来说，套接字是平等的，并没有差别，不因为在服务器端或在客户端而产生不同级别。

2 TCPServer代码实例

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.Date;

import java.util.HashMap;

import java.util.Map;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

* TCP服务器端,单例模式

* @author xiang

*

*/

public class TCPServer implements Runnable {

private static final Logger logger = LoggerFactory.getLogger(TCPServer.class);

//成员变量/

private static TCPServer serverInstance;

private static Map socketMaps = new HashMap();　　　　　　　　//每个客户端连接时都会新建一个SocketThread与之对应 private static ServerSocket serverSocket; //服务器套接字

private static int serPort = 9999; //服务器端口号

private static boolean flag; //服务器状态标志

private static final int BUFFER_SIZE = 512; //数据接收字符数组大小

//构造函数/

private TCPServer() {

}

/**

* 获取实例

* @return TCPServer实例serverInstance

*/

public static TCPServer getServerInstance(){

if(serverInstance==null)

serverInstance = new TCPServer();

return serverInstance;

}

/**

* 开启服务器

* @throws IOException

*/

pubVEKgYlic void openTCPServer() throws IOException{ if(serverSocket==null || serverSocket.isClosed()){

serverSocket = new ServerSocket(serPort);

flag = true;

}

}

/**

* 关闭服务器

* @throws IOException

*/

public void closeTCPServer() throws IOException{

flag = false; if(serverSocket!=null)

serverSocket.close();

/*for (Map.Entry entry : socketMaps.entrySet()) {

System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());

} */

for (SocketThread value : socketMaps.values())

value.closeConnect();

socketMaps.clear();

}

/**

* 服务器向客户端发送数据

* @param bytes[]:待发送的字符数组

* @param key 客户端的key,为空或""时表示数据群发

* @throws IOException

*/

public void sendMessage(String key,byte[] msgBytes){

if(key==null||key.equals("")){

for (SocketThread value : socketMaps.values())

value.sendMassage(msgBytes);

}else{

SocketThread thread = socketMaps.get(key);

if(thread!=null)

thread.sendMassage(msgBytes);

}

}

/**

* 服务器向客户端发送数据

* @param key 客户端的key,为空或""时表示数据群发

* @param msgStr:待发送的字符串

* @throws IOException

*/

public void sendMessage(String key,String msgStr){ byte[] sendByte = msgStr.getBytes();

if(key==null||key.equals("")){

for (SocketThread value : socketMaps.values())

value.sendMassage(sendByte);

}else{

SocketThread thread = socketMaps.get(key);

if(thread!=null)

thread.sendMassage(sendByte);

}

}

@Override

public void run() {

logger.info("服务器线程已经启动"); while(true){

try {

while(flag){

logger.info("服务器线程在监听状态中");

Socket socket = serverSocket.accept();

String key = socket.getRemoteSocketAddress().toString();

SocketThread thread = new SocketThread(socket,key);

thread.start();

socketMaps.put(key, thread);

logger.info("有客户端连接："+key);

}

} catch (Exception e) {

e.printStackTrace();

}

}

}

/**

* 处理连接后的数据接收请求内部类

* @author xiang

*

*/

private class SocketThread extends Thread{

private Socket socket;

private String key;

private OutputStream out;

private InputStream in;

//构造函数

public SocketThread(Socket socket,String key) {

this.socket = socket;

this.key = key;

}

/**

* 发送数据

* @param bytes

* @throws IOException

*/

public void sendMassage(byte[] bytes){

try {

if(out==null)

out = socket.getOutputStream();

out.write(bytes);

} catch (Exception e) {

e.printStackTrace();

try {

closeConnect();

} catch (IOException e1) {

e1.printStackTrace();

}

socketMaps.remove(key);

}

}

/**

* 关闭连接，释放资源

* @throws IOException

*/

public void closeConnect() throws IOException{

if(out!=null) out.close();

if(in!=null) in.close();

if(socket!=null && socket.isConnected()) socket.close();

}

@Override

public void run() {

byte[] receivBuf = new byte[BUFFER_SIZE];

int recvMsgSize;

try {

in = socket.getInputStream();

out = socket.getOutputStream();

while ((recvMsgSize = in.read(receivBuf)) != -1) {

String receivedData = new String(receivBuf, 0, recvMsgSize);

System.out.println("Reverve form[port" + socket.getPort() + "]:" + receivedData);

System.out.println("Now the size of socketMaps is" + socketMaps.size());

/**************************************************************

*

* 接收数据后的处理过程

*

**************************************************************/

}

// response to client

byte[] sendByte = "The Server has received".getBytes();

// out.write(sendByte, 0, sendByte.length);

out.write(sendByte);

System.out.println("To Cliect[port:" + socket.getPort() + "] 回复客户端的消息发送成功");

closeConnect();

socketMaps.remove(key);

} catch (Exception e) {

e.printStackTrace();

try {

closeConnect();

} catch (IOException e1) {

e1.printStackTrace();

}

}

}

//////////////

public int getport(){

return socket.getPort();

}

}

//. end SocketThread

}

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