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 IOExceptionByteBuffer 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.positionbytes = 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bufferByteBuffer buffer = ByteBuffer.wrap(responseString.getBytes());try{socketChannel.write(buffer);}catch (IOException e) {System.out.println("IO:"+e.getMessage());}catch (Exception e) {e.printStackTrace();}}}