Java nio 学习笔记（五）

Java nio SocketChannel ServerSocketChannel 以及Selector实现的echo服务器和客户端（暂时有问题）

服务器端代码：

[java] view
plaincopy

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.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);

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

System.out.println("监听新事件...");

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("deal with new accept...");

ServerSocketChannel server = (ServerSocketChannel)key.channel();

SocketChannel sc = server.accept();

sc.configureBlocking(false);

//注册读事件

sc.register(s, SelectionKey.OP_WRITE);

System.out.println("deal with new accept2...");

} 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();

sc.write(r_bBuf);

r_bBuf.flip();

System.out.println(r_bBuf.asCharBuffer().toString());

r_bBuf.clear();

System.out.println("处理完毕...");

try {

Thread.currentThread().sleep(1000);

} catch (InterruptedException e) {

e.printStackTrace();

}

} catch (IOException e) {

e.printStackTrace();

}

}

private String getCurrentTime() {

return Calendar.getInstance().toString();

}

}

client 端代码：

[java] view
plaincopy

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;

public class TestClient {

public static void main(String[] args) {

new MiniClient("localhost", 1982);

}

}

class MiniClient {

private SocketChannel sc;

private ByteBuffer w_bBuf;

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.isConnected()) {

System.out.println("已经与服务器失去了连接...");

}

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());

w_bBuf.flip();

//向缓冲区中写入数据

sc.write(w_bBuf);

System.out.println("数据发送成功...");

w_bBuf.clear();

try {

Thread.currentThread().sleep(1000);

} catch (InterruptedException e) {

e.printStackTrace();

}

}

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

Thinking in java中的一个图片，刚找到的，比较清楚关系图。