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import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.UnsupportedEncodingException;import java.net.InetSocketAddress;import java.net.ServerSocket;import java.net.Socket;import java.net.SocketAddress;import java.util.Collections;import java.util.HashMap;import java.util.Map;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;import java.util.logging.Level;import java.util.logging.Logger;public class TCPServer implements Runnable{	/*绑定监听IP:port	 * 1、起一个主线程进行监听，采用 thread per request的方式处理请求；	 * 2、每个请求，回送一个应答*/	public static final int MAX_THREAD = 10;		private String ip = null;	private int port = 0;	private SocketAddress listeningAddress = null;	private ServerSocket serverSocket = null;	private Logger logger = Logger.getLogger(this.getClass().getName());  //Use default logger of JAVA	private Socket connSocket = null;	private ExecutorService threadpool = Executors.newFixedThreadPool(MAX_THREAD);	private Map
   
     connectionPool = Collections.synchronizedMap(new HashMap
    
     ());		public volatile boolean isRunning = true;		public TCPServer(String ip,int port) {		this.ip = ip;		this.port = port; 		listeningAddress = new InetSocketAddress(ip, port);				try {			serverSocket = new ServerSocket(port, 0, ((InetSocketAddress)listeningAddress).getAddress());			logger.log(Level.INFO, "Server started...listening on "+this.ip+":"+this.port);		} catch (IOException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}	}			@Override	public void run() {		// TODO Auto-generated method stub		while( true == isRunning )		{			try {				connSocket = serverSocket.accept();				if( null != connSocket )				{					//handle connect in newly constructed thread					Future
      future = threadpool.submit(new RequestHandler(connSocket));					String connectionKey = new String(connSocket.getInetAddress().getHostAddress()+":"+connSocket.getPort());					connectionPool.put(connectionKey, new ConnectionInfo(future,connSocket));  /*讲连接放入server的连接池，便于后续使用*/				}			} catch (IOException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}					}	}		private class ConnectionInfo {		public Future
      future = null;		public Socket socket = null;				public ConnectionInfo(Future
      future,Socket socket) {			this.future = future;			this.socket = socket;		}	}		private class RequestHandler implements Runnable {		private final int RECV_BUF_LEN = 1024;		private Socket connSocket = null;		private InputStream in = null;		private OutputStream out = null;		private BufferedInputStream bufin = null;		private BufferedOutputStream bufout = null;		private boolean isRunning = true;		private byte[] recvbuffer = new byte[RECV_BUF_LEN];  		private int handleswitch = 2;		//recvbuffer := make([]byte,1024,1024)  /*define a slice in golang*/		//var recvbuffer [1024] byte   /*define an array in golang*/				public RequestHandler(Socket connSocket) {			this.connSocket = connSocket;		}				@Override		public void run() {			if( null != connSocket ) {				try {					in = connSocket.getInputStream();					out = connSocket.getOutputStream();										bufin = new BufferedInputStream(connSocket.getInputStream());					//bufout = new BufferedOutputStream(connSocket.getOutputStream(),200);					/*如果创建的时候不指定buffer大小，默认是8K；如果buffer较小，buffer满的时候会自动执行flush；stream关闭的时候，会自动flush*/					bufout = new BufferedOutputStream(connSocket.getOutputStream());				} catch (IOException e1) {					// TODO Auto-generated catch block					e1.printStackTrace();				}											}						// TODO Auto-generated method stub			//get info from the socket via stream			while( !Thread.currentThread().isInterrupted() && true == isRunning) {				if( null != connSocket ) {					if( handleswitch == 1 ) {						//第一种方式，通过传统的stream方式读取						if( null != in && null != out)						{							// in.read(); /*返回stream中的下一个byte，作为int类型返回，如果stream到达末尾，则返回-1*/							try {								int cnt = in.read(recvbuffer);								if( cnt > 0) {									//recv success									String received = new String(recvbuffer,0,cnt);  /*注意使用有效的数据长度，而不是整个buffer的长度创建string，避免乱码*/									//logger.log(Level.INFO, "Received: "+received);																		//send an echo as soon as possible									String response = new String("I'm the server,received your message:"+received);									logger.log(Level.INFO, response);									out.write(response.getBytes());								}							} catch (IOException e) {								// TODO Auto-generated catch block								e.printStackTrace();								//send an event to TCPSever to notify it to handle connection failure.								isRunning = false;							}						}					} else if( handleswitch == 2 ) {						//第二种方式，使用bufferedstream的方式读取						if( bufin != null && bufout != null ) {							try {								int cnt = bufin.read(recvbuffer);  //底层是调用InputStream的read逐个字节读到buffer里的								if( cnt > 0 ) {									String received = new String(recvbuffer,0,cnt);  /*注意使用有效的数据长度，而不是整个buffer的长度创建string，避免乱码*/									//logger.log(Level.INFO, received);																		//send an echo as soon as possible									String response = new String("I'm the server,received your message:"+received);									logger.log(Level.INFO, response);																		bufout.write(response.getBytes());									bufout.flush();								}							} catch (IOException e) {								// TODO Auto-generated catch block								e.printStackTrace();								try {									connSocket.close();								} catch (IOException e1) {									// TODO Auto-generated catch block									e1.printStackTrace();								}								isRunning = false;							}						}												/*综上：个人认为，bufferedstream的意义，在发送的时候大于接收的时候，从源码看到，接收的时候，基本还是调用底层的read逐个字节读的；						 * 在发送端，业务线程可以不断把数据往buffer里填，直到需要发送或者buffer满的时候，调用或触发flush将数据提交给OS（并非提交给						 * 物理设备，如网卡），这样在某些场景下，业务线程不必每填一次数据都write一把，提高了效率。*/					} else if( handleswitch == 3 ) {						//第三种方式，使用reader/writer方式读取						try {							//从字节流到字符流再到文本							BufferedReader br = new BufferedReader(new InputStreamReader(connSocket.getInputStream(), "UTF-8"));							if( null != br ) {								String line = null;								//BufferedReader 有几种读的方式：1、逐个字符读取；2、将字符流顺序读取到指定的缓存中；3、逐行读取（以换行符为准）								while( null != ( line = br.readLine()) ) {    									//readline 以换行符、字符串结束符为准									//如果读不到行结束，该调用会阻塞并一直读取，直到字符流结束，内部用StringBuffer保存每次读取的string									logger.log(Level.INFO, "Server received:"+line);								}							}						} catch (UnsupportedEncodingException e) {							// TODO Auto-generated catch block							e.printStackTrace();						} catch (IOException e) {							// TODO Auto-generated catch block							e.printStackTrace();						}					}														} else {					logger.log(Level.INFO, "Socket is null! Stop reading!");					isRunning = false;				}			}		}			}}
    
   

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