java的nio例子

package main;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

//import java.nio.channels.ClosedChannelException;

import java.nio.channels.SelectionKey;

import java.nio.channels.Selector;

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

import java.util.Iterator;

public class JsonSocketServer{

	private static int PORT = 9090;

	public static void main(String[] args) {

		System.out.println("Server try start ..");

		Selector selector = null;

		ServerSocketChannel serverSocketChannel = null;

		try{

			selector = Selector.open();

			serverSocketChannel = ServerSocketChannel.open();

			serverSocketChannel.configureBlocking(false);

			serverSocketChannel.socket().setReuseAddress(true);

			serverSocketChannel.socket().bind(new InetSocketAddress(PORT) );

			//注册可读事件

			serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

			while (selector.select()>0) {//select()可指定超时参数

				Iterator<SelectionKey> it = selector.selectedKeys().iterator();

				while (it.hasNext()) {

					SelectionKey readyKey = it.next();

					it.remove();

					handleConnection((ServerSocketChannel) readyKey.channel());

				}

			}

		}catch (IOException e){

			System.out.println("IO:"+e.getMessage());

		}catch (Exception e){

			e.printStackTrace();

		}finally{

			try{

				serverSocketChannel.close();

				selector.close();

			}catch (Exception e) {

				e.printStackTrace();

			}

		}

	}

	private static void handleConnection(ServerSocketChannel serverSocketChannel) throws IOException {

		SocketChannel socketChannel = null;

		try{

			socketChannel = serverSocketChannel.accept();

			socketChannel.configureBlocking(false);

			String recvShow = new String(recevceData(socketChannel));

			//System.out.println("recv :"+recvShow);

			sendData(socketChannel);

		} catch (IOException e) {

			System.out.println("IO"+e.getMessage());

		} catch (Exception e) {

			e.printStackTrace();

		}finally{

			socketChannel.close();

		}

	}

	private static byte[] recevceData(SocketChannel socketChannel) throws IOException {

		int datagramHead = 4;

		int recvTimes = 5;

		//方法使用的数据类型 ByteBuffer java.nio.channels.SocketChannel.read(ByteBuffer arg0) throws IOException

		ByteBuffer buffer = ByteBuffer.allocate(1500);

		ByteArrayOutputStream baos = new ByteArrayOutputStream();

		byte[] bytes=null;

		int len,lenInfo=-1,offset=0;

		String s;

		try {

			while(true){

				len = socketChannel.read(buffer);

				if(len<0){

					System.out.println("read return "+len);

					break;

				}

				offset += len;

				if(len == 0){

					if(lenInfo + datagramHead <= offset && lenInfo != -1){

						break;

					}

					else {

						if(--recvTimes == 0)

							break;

						Thread.sleep(10);

						continue;

					}

				}

				buffer.flip();//复位ByteBuffer.position

				bytes = new byte[len];

				buffer.get(bytes);//把position到limit之间的数据复制到bytes，position会变化

				baos.write(bytes);//将本次接收写入缓冲区

				if(lenInfo == -1){

					s = new String(baos.toByteArray());

					lenInfo = Integer.parseInt(s.substring(0,datagramHead));

					//System.out.println("len is "+lenInfo);

					if(lenInfo + datagramHead <= offset){

						break;

					}

				}

				buffer.clear();//恢复buffer的初始状态

			}

			if(len >= 0){

				bytes = baos.toByteArray();

			}

			else {

				bytes = new byte[0];

			}

		}catch (IOException e) {

			System.out.println("IO"+e.getMessage());

		} catch (Exception e) {

			e.printStackTrace();

		}finally{

			baos.close();//关闭缓冲区

		}

		return bytes;

	}

	private static void sendData(SocketChannel socketChannel)throws IOException {

		String responseString = "heeeeeee";

		//将bytes数组内容写入buffer

		ByteBuffer buffer = ByteBuffer.wrap(responseString.getBytes());

		try{

			socketChannel.write(buffer);

		}catch (IOException e) {

			System.out.println("IO:"+e.getMessage());

		}

		catch (Exception e) {

			e.printStackTrace();

		}

	}

}
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java的nio例子

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