Java Socket NIO示例总结

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.util.Iterator;public class NIOServer { private static int BUFF_SIZE=1024;
private static int TIME_OUT = 2000;
public static void main(String[] args) throws IOException { Selector selector = Selector.open();
ServerSocketChannel serverSocketChannel=ServerSocketChannel.open();
serverSocketChannel.bind(new InetSocketAddress(10083));
serverSocketChannel.configureBlocking(false);
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT); TCPProtocol protocol = new EchoSelectorProtocol(BUFF_SIZE); while (true) {
if(selector.select(TIME_OUT)==0){
//在等待信道准备的同时，也可以异步地执行其他任务， 这里打印*
System.out.print("*");
continue;
}
Iterator<SelectionKey> keyIter = selector.selectedKeys().iterator();
while (keyIter.hasNext()) {
SelectionKey key = keyIter.next();
//如果服务端信道感兴趣的I/O操作为accept
if (key.isAcceptable()){
protocol.handleAccept(key);
}
//如果客户端信道感兴趣的I/O操作为read
if (key.isReadable()){
protocol.handleRead(key);
}
//如果该键值有效，并且其对应的客户端信道感兴趣的I/O操作为write
if (key.isValid() && key.isWritable()) {
protocol.handleWrite(key);
} //这里需要手动从键集中移除当前的key
keyIter.remove();
} }
}
}

import java.io.IOException;
import java.nio.channels.SelectionKey;public interface TCPProtocol { void handleAccept(SelectionKey key) throws IOException; void handleRead(SelectionKey key) throws IOException; void handleWrite(SelectionKey key) throws IOException;}

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;public class EchoSelectorProtocol implements TCPProtocol { private int bufSize; // 缓冲区的长度
public EchoSelectorProtocol(int bufSize){
this.bufSize = bufSize;
} @Override
public void handleAccept(SelectionKey key) throws IOException {
System.out.println("Accept");
SocketChannel socketChannel = ((ServerSocketChannel)key.channel()).accept();
socketChannel.configureBlocking(false);
socketChannel.register(key.selector(), SelectionKey.OP_READ, ByteBuffer.allocate(bufSize)); } @Override
public void handleRead(SelectionKey key) throws IOException {
SocketChannel clntChan = (SocketChannel) key.channel();
//获取该信道所关联的附件，这里为缓冲区
ByteBuffer buf = (ByteBuffer) key.attachment();
buf.clear();
long bytesRead = clntChan.read(buf);
//如果read（）方法返回-1，说明客户端关闭了连接，那么客户端已经接收到了与自己发送字节数相等的数据，可以安全地关闭
if (bytesRead == -1){
clntChan.close();
}else if(bytesRead > 0){
//如果缓冲区总读入了数据，则将该信道感兴趣的操作设置为为可读可写
key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
} } @Override
public void handleWrite(SelectionKey key) throws IOException {
// TODO Auto-generated method stub
ByteBuffer buffer=(ByteBuffer) key.attachment();
buffer.flip();
SocketChannel clntChan = (SocketChannel) key.channel();
//将数据写入到信道中
clntChan.write(buffer);
if (!buffer.hasRemaining()){ //如果缓冲区中的数据已经全部写入了信道，则将该信道感兴趣的操作设置为可读
key.interestOps(SelectionKey.OP_READ);
}
//为读入更多的数据腾出空间
buffer.compact(); }}

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;public class NIOClient { public static void main(String[] args) throws IOException {
SocketChannel clntChan = SocketChannel.open();
clntChan.configureBlocking(false);
if (!clntChan.connect(new InetSocketAddress("localhost", 10083))){
//不断地轮询连接状态，直到完成连接
while (!clntChan.finishConnect()){
//在等待连接的时间里，可以执行其他任务，以充分发挥非阻塞IO的异步特性
//这里为了演示该方法的使用，只是一直打印"."
System.out.print(".");
}
} //为了与后面打印的"."区别开来，这里输出换行符
System.out.print("\n");
//分别实例化用来读写的缓冲区 ByteBuffer writeBuf = ByteBuffer.wrap("send send send".getBytes());
ByteBuffer readBuf = ByteBuffer.allocate("send".getBytes().length-1); while (writeBuf.hasRemaining()) {
//如果用来向通道中写数据的缓冲区中还有剩余的字节，则继续将数据写入信道
clntChan.write(writeBuf); }
StringBuffer stringBuffer=new StringBuffer();
//如果read（）接收到-1，表明服务端关闭，抛出异常
while ((clntChan.read(readBuf)) >0){
readBuf.flip();
stringBuffer.append(new String(readBuf.array(),0,readBuf.limit()));
readBuf.clear();
} //打印出接收到的数据
System.out.println("Client Received: " + stringBuffer.toString());
//关闭信道
clntChan.close();
}
}