Java nio 实现socket异步通信 （对Java nio 实习笔记五中内容做一纠正）

原始错误版本请看：http://blog.csdn.net/tsyj810883979/article/details/6877216

在原有基础上考虑了编码与解码的问题，还有消息发送的两个重要方法调用疏忽

public abstract int write(ByteBuffer src)     将字节序列从给定的缓冲区中写入此通道。 
public abstract int read(ByteBuffer dst)     将字节序列从此通道中读入给定的缓冲区。

下面代码在关闭连接时还有问题，服务器可以与客户端断开，但是客户端断开后没有退出，再次操作会出现异常。

 

服务器端代码实现：

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Calendar;
import java.util.Iterator;


public class TestServer {
	public static void main(String[] args) {
		new Thread(new EchoServer(1982)).start();
	}
}

class EchoServer implements Runnable {
	//要监听的端口号
	private int port;
	//生成一个信号监视器
	private Selector s;
	//读缓冲区
	private ByteBuffer r_bBuf = ByteBuffer.allocate(1024);
	private ByteBuffer w_bBuf;
	
	public EchoServer(int port) {
		this.port = port;
		try {
			s = Selector.open();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	@Override
	public void run() {
		try {
			//生成一个ServerScoket通道的实例对象，用于侦听可能发生的IO事件
			ServerSocketChannel ssc = ServerSocketChannel.open();
			//将该通道设置为异步方式
			ssc.configureBlocking(false);
			//绑定到一个指定的端口
			ssc.socket().bind(new InetSocketAddress(port));
			//注册特定类型的事件到信号监视器上
			ssc.register(s, SelectionKey.OP_ACCEPT);
			System.out.println("The server has been launched...");
			while(true) {
				//将会阻塞执行，直到有事件发生
				s.select();
				Iterator<SelectionKey> it = s.selectedKeys().iterator();
				while(it.hasNext()) {
					SelectionKey key = it.next();
					//key定义了四种不同形式的操作
					switch(key.readyOps()) {
					case SelectionKey.OP_ACCEPT :
						dealwithAccept(key);
						break;
					case SelectionKey.OP_CONNECT :
						break;
					case SelectionKey.OP_READ :
						dealwithRead(key);
						break;
					case SelectionKey.OP_WRITE :
						break;
					}
					//处理结束后移除当前事件，以免重复处理
					it.remove();
				}
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	//处理接收连接的事件
	private void dealwithAccept(SelectionKey key) {
		try {
			System.out.println("新的客户端请求连接...");
			ServerSocketChannel server = (ServerSocketChannel)key.channel();
			SocketChannel sc = server.accept();
			sc.configureBlocking(false);
			//注册读事件
			sc.register(s, SelectionKey.OP_READ);
			System.out.println("客户端连接成功...");
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	//处理客户端发来的消息，处理读事件
	private void dealwithRead(SelectionKey key) {
		try {
			SocketChannel sc = (SocketChannel)key.channel();
			System.out.println("读入数据");
			r_bBuf.clear();
			//将字节序列从此通道中读入给定的缓冲区r_bBuf
			sc.read(r_bBuf);
			r_bBuf.flip();
			String msg = Charset.forName("UTF-8").decode(r_bBuf).toString();
			if(msg.equalsIgnoreCase("time")) {
				w_bBuf = ByteBuffer.wrap(getCurrentTime().getBytes("UTF-8"));
				sc.write(w_bBuf);
				w_bBuf.clear();
			} else if(msg.equalsIgnoreCase("bye")) {
				sc.write(ByteBuffer.wrap("已经与服务器断开连接".getBytes("UTF-8")));
				sc.socket().close();
			} else {
				sc.write(ByteBuffer.wrap(msg.getBytes("UTF-8")));
			}
			System.out.println(msg);
			System.out.println("处理完毕...");
			r_bBuf.clear();
			try {
				Thread.currentThread();
				Thread.sleep(100);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	private String getCurrentTime() {
		Calendar date = Calendar.getInstance();
		String time = "服务器当前时间：" +
					  date.get(Calendar.YEAR) + "-" +
					  date.get(Calendar.MONTH)+1 + "-" +
					  date.get(Calendar.DATE) + " " +
					  date.get(Calendar.HOUR) + ":" +
					  date.get(Calendar.MINUTE) + ":" +
					  date.get(Calendar.SECOND);
		return time;
	}
}

 

客户端代码实现：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;

public class TestClient {
	public static void main(String[] args) {
		new MiniClient("localhost", 1982);
	}
}
class MiniClient {
	private SocketChannel sc;
	private ByteBuffer w_bBuf;
	private ByteBuffer r_bBuf = ByteBuffer.allocate(1024);
	public MiniClient(String host, int port) {
		try {
			InetSocketAddress remote = new InetSocketAddress(host, port);
			sc = SocketChannel.open();
			sc.connect(remote);
			if(sc.finishConnect()) {
				System.out.println("已经与服务器成功建立连接...");
			}
			while(true) {
				if(!sc.socket().isConnected()) {
					System.out.println("已经与服务器失去了连接...");
					return ;
				}
				BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
				String str = br.readLine();
				System.out.println("读入一行数据，开始发送...");
				w_bBuf = ByteBuffer.wrap(str.getBytes("UTF-8"));
				//将缓冲区中数据写入通道
				sc.write(w_bBuf);
				System.out.println("数据发送成功...");
				w_bBuf.clear();
				System.out.println("接收服务器端响应消息...");
				try {
					Thread.currentThread();
					Thread.sleep(100);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				r_bBuf.clear();
				//将字节序列从此通道中读入给定的缓冲区r_bBuf
				sc.read(r_bBuf);
				r_bBuf.flip();
				String msg = Charset.forName("UTF-8").decode(r_bBuf).toString();
				System.out.println(msg);				
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}