Java -socket接口(監聽)

最近項目涉及到與C的通訊，目的是轉發一下信息，Java這邊使用的時監聽Socket的接口，只要給C提供IP和端口 就行了。

已知Socket的編程有 TCP和UDP協議，據說UDP更快一點 這里使用的UDP編程

1.創建一個服務類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;//監聽的端口號
    private static final Logger LOGGER = LoggerFactory.getLogger(PushPrinterServer.class);
    private DatagramSocket datagramSocket=null;

    public PushPrinterServer(DatagramSocket datagramSocket) {
        if (datagramSocket==null){
            try {
                LOGGER.info("開啟推送打印服務器端口"+PORT);
                this.datagramSocket = new DatagramSocket(PORT);
            }catch (Exception e){
                LOGGER.error("開啟socket推送打印服務出錯");
                e.printStackTrace();
            }
        }
    }
    @Override
    public void run() {
        try {
            while (!this.isInterrupted()) {
//                // 一旦有堵塞, 則表示服務器與客戶端獲得了連接
                byte[] receiveData = new byte[1024];
                DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
                datagramSocket.receive(receivePacket);// 在接收到信息之前，一直保持阻塞狀態

                String encoding = GetByteEncode.getEncoding(receiveData);//編碼判斷
                System.out.println("字符編碼是："+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("客戶端發送消息:"+data);
                try {
                    if(receiveData!=null){
                        HttpClientUtil.requestHttpPost(data,PRINTER_URL);
                        LOGGER.info("已向管理平台發送請求...");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                    LOGGER.info("向管理平台發送請求失敗");
                }

            }
        } catch (Exception e) {
            LOGGER.error("推送打印異常: " + e.getMessage());
        }
    }

    public void closeSocketServer(){
        if(null!=datagramSocket && !datagramSocket.isClosed())
        {
            LOGGER.info("關閉推送打印服務器");
            datagramSocket.close();
        }
    }
}

-----------------------------------------------------------------------------------------------

receiveData 是監聽接口收到是字節組的源數據，由於發過來的中文亂碼，但一直處理不了，所有這里先查出源數據的編碼格式，再進行處理，data是處理
完的數據，然后轉發一下就好了。

2.創建一個監聽類PushPrinterSocketServiceLoader
網上許多寫的多寫在main方法里面，但是真實的項目怎么辦呢，要讓它項目已啟動就開啟線程監聽，創建監聽類

import com.service.PushPrinterServer;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class PushPrinterSocketServiceLoader implements ServletContextListener {
    //socket server 線程
    private PushPrinterServer pushPrinterServer;
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        if(null==pushPrinterServer)
        {
            //新建線程類
            pushPrinterServer=new PushPrinterServer(null);
            //啟動線程
            pushPrinterServer.start();
        }
    }
    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        if(null!=pushPrinterServer && !pushPrinterServer.isInterrupted())
        {
            System.out.println("推送打印服務器關閉");
            pushPrinterServer.closeSocketServer();
            pushPrinterServer.interrupt();
        }
    }
}

3.在web.xml添加配置

<listener>
    <listener-class>com.listener.PushPrinterSocketServiceLoader</listener-class>
</listener>