最近项目涉及到与C的通讯，目的是转发一下信息，Java这边使用的时监听Socket的接口，只要给C提供IP和端口 就行了。

已知Socket的编程有 TCP和UDP协议，据说UDP更快一点 这里使用的UDP编程

1.创建一个服务类PushPrinterServer

import com.util.GetByteEncode;

import com.util.HttpClientUtil;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.nio.ByteBuffer;

import java.nio.CharBuffer;

import java.nio.charset.Charset;

import static com.constants.PrinterSocketConstants.PRINTER_URL;

public class PushPrinterServer extends Thread {

private static final int PORT=9002;//监听的端口号

private static final Logger LOGGER = LoggerFactory.getLogger(PushPrinterServer.class);

private DatagramSocket datagramSocket=null;

public PushPrinterServer(DatagramSocket datagramSocket) {

if (datagramSocket==null){

try {

LOGGER.info("开启推送打印服务器端口"+PORT);

this.datagramSocket = new DatagramSocket(PORT);

}catch (Exception e){

LOGGER.error("开启socket推送打印服务出错");

e.printStackTrace();

}

}

}

@Override

public void run() {

try {

while (!this.isInterrupted()) {

// // 一旦有堵塞, 则表示服务器与客户端获得了连接

byte[] receiveData= new byte[1024];

DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);

datagramSocket.receive(receivePacket);// 在接收到信息之前，一直保持阻塞状态

String encoding = GetByteEncode.getEncoding(receiveData);//编码判断

System.out.println("字符编码是："+encoding);

ByteBuffer byteBuffer = ByteBuffer.wrap(receiveData);

CharBuffer gb18030 = Charset.forName("GB18030").decode(byteBuffer);

ByteBuffer utf8 = Charset.forName("UTF8").encode(gb18030);

String data= new String(utf8.array());

LOGGER.info("客户端发送消息:"+data);

try {

if(receiveData!=null){

HttpClientUtil.requestHttpPost(data,PRINTER_URL);

LOGGER.info("已向管理平台发送请求...");

}

} catch (Exception e) {

e.printStackTrace();

LOGGER.info("向管理平台发送请求失败");

}

}

} catch (Exception e) {

LOGGER.error("推送打印异常: " + e.getMessage());

}

}

public void closeSocketServer(){

if(null!=datagramSocket && !datagramSocket.isClosed())

{

LOGGER.info("关闭推送打印服务器");

datagramSocket.close();

}

}

}

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receiveData 是监听接口收到是字节组的源数据，由于发过来的中文乱码，但一直处理不了，所有这里先查出源数据的编码格式，再进行处理，data是处理

完的数据，然后转发一下就好了。

2.创建一个监听类PushPrinterSocketServiceLoader

网上许多写的多写在main方法里面，但是真实的项目怎么办呢，要让它项目已启动就开启线程监听，创建监听类

import com.service.PushPrinterServer;

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

public class PushPrinterSocketServiceLoader implements ServletContextListener {

//socket server 线程

private PushPrinterServer pushPrinterServer;

@Override

public void contextInitialized(ServletContextEvent servletContextEvent) {

if(null==pushPrinterServer)

{

//新建线程类

pushPrinterServer=new PushPrinterServer(null);

//启动线程

pushPrinterServer.start();

}

}

@Override

public void contextDestroyed(ServletContextEvent servletContextEvent) {

if(null!=pushPrinterServer && !pushPrinterServer.isInterrupted())

{

System.out.println("推送打印服务器关闭");

pushPrinterServer.closeSocketServer();

pushPrinterServer.interrupt();

}

}

}

3.在web.xml添加配置

com.listener.PushPrinterSocketServiceLoader