java nio过程
1、服务端：ServerSocketChannel进行监听，注册SelectionKey.OP_ACCEPT事件，服务器阻塞在selector.select()方法中，等待客户端连接。
2、客户端：SocketChannel创建连接，调用socketChannel.connect(SERVER_ADDRESS)连接服务器（此时服务器之前阻塞在selector.select()往下走，进入selectionKey.isAcceptable()逻辑，通过ServerSocketChannel的accept方法获得客户端SocketChannel，SocketChannel注册 SelectionKey.OP_READ事件，等待客户端输入流，此时又阻塞在selector.select()方法），客户端进入selectionKey.isConnectable()，如果client.isConnectionPending()==true，通过 client.finishConnect()强制连接，然后准备数据，通过client.write(sendbuffer)向服务器发送数据，此时，服务器之前阻塞在selector.select()往下走，进入selectionKey.isReadable()逻辑，通过缓冲区读取客户端输入流，然后调用client.register(selector, SelectionKey.OP_WRITE)注册写客户端流事件，进入selectionKey.isWritable()逻辑，准备写客户端的数据，通过client.write(sendbuffer)方法写给客户端，客户端之前write之后，会进行注册SelectionKey.OP_READ，等待服务器响应，阻塞在selector.select()中，由于这个时候服务器有了返回，就不阻塞了，进入selectionKey.isReadable()逻辑，得到服务器返回，如果需要再次发送数据给服务器，则注册write事件。刚才服务器write给客户端之后，如果想继续收到客户端数据，需要注册client.register(selector, SelectionKey.OP_READ)读事件，等待客户端再一次写入数据，阻塞在selector.select()方法
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服务端：
package com.rb.socket.nio.server.n;import java.io.IOException;import java.net.InetSocketAddress;import java.net.ServerSocket;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.Iterator;import java.util.Set;public class NIOServer {/*标识数字*/private int flag = 0;/*缓冲区大小*/private int BLOCK = 4096;/*接受数据缓冲区*/private ByteBuffer sendbuffer = ByteBuffer.allocate(BLOCK);/*发送数据缓冲区*/private ByteBuffer receivebuffer = ByteBuffer.allocate(BLOCK);private Selector selector;public NIOServer(int port) throws IOException {// 打开服务器套接字通道 ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();// 服务器配置为非阻塞 serverSocketChannel.configureBlocking(false);// 检索与此通道关联的服务器套接字 ServerSocket serverSocket = serverSocketChannel.socket();// 进行服务的绑定 serverSocket.bind(new InetSocketAddress(port));// 通过open()方法找到Selector selector = Selector.open();// 注册到selector，等待连接 serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);System.out.println("Server Start----:" + port);}// 监听 private void listen() throws IOException {while (true) {// 选择一组键，并且相应的通道已经打开 selector.select();// 返回此选择器的已选择键集。 Set<SelectionKey> selectionKeys = selector.selectedKeys();Iterator<SelectionKey> iterator = selectionKeys.iterator();while (iterator.hasNext()) {SelectionKey selectionKey = iterator.next();iterator.remove();handleKey(selectionKey);}}}// 处理请求 private void handleKey(SelectionKey selectionKey) throws IOException {// 接受请求 ServerSocketChannel server = null;SocketChannel client = null;String receiveText;String sendText;int count = 0;// 测试此键的通道是否已准备好接受新的套接字连接。 if (selectionKey.isAcceptable()) {// 返回为之创建此键的通道。 server = (ServerSocketChannel) selectionKey.channel();// 接受到此通道套接字的连接。 // 此方法返回的套接字通道（如果有）将处于阻塞模式。 client = server.accept();// 配置为非阻塞 client.configureBlocking(false);// 注册到selector，等待连接 client.register(selector, SelectionKey.OP_READ);} else if (selectionKey.isReadable()) {// 返回为之创建此键的通道。 client = (SocketChannel) selectionKey.channel();//将缓冲区清空以备下次读取 receivebuffer.clear();//读取服务器发送来的数据到缓冲区中 count = client.read(receivebuffer);if (count > 0) {receiveText = new String(receivebuffer.array(), 0, count);System.out.println("服务器端接受客户端数据--:" + receiveText);client.register(selector, SelectionKey.OP_WRITE);}} else if (selectionKey.isWritable()) {//将缓冲区清空以备下次写入 sendbuffer.clear();// 返回为之创建此键的通道。 client = (SocketChannel) selectionKey.channel();sendText = "message from server--" + flag++;//向缓冲区中输入数据 sendbuffer.put(sendText.getBytes());//将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位 sendbuffer.flip();//输出到通道 client.write(sendbuffer);System.out.println("服务器端向客户端发送数据--：" + sendText);client.register(selector, SelectionKey.OP_READ);}}/** * @param args * @throws IOException */public static void main(String[] args) throws IOException {// TODO Auto-generated method stub int port = 8011;NIOServer server = new NIOServer(port);server.listen();}}?
客户端：
package com.rb.socket.nio.server.n;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.SocketChannel; import java.util.Iterator; import java.util.Set; public class NIOClient { /*标识数字*/ private static int flag = 0; /*缓冲区大小*/ private static int BLOCK = 4096; /*接受数据缓冲区*/ private static ByteBuffer sendbuffer = ByteBuffer.allocate(BLOCK); /*发送数据缓冲区*/ private static ByteBuffer receivebuffer = ByteBuffer.allocate(BLOCK); /*服务器端地址*/ private final static InetSocketAddress SERVER_ADDRESS = new InetSocketAddress( "localhost", 8011); public static void main(String[] args) throws IOException { // TODO Auto-generated method stub // 打开socket通道 SocketChannel socketChannel = SocketChannel.open(); // 设置为非阻塞方式 socketChannel.configureBlocking(false); // 打开选择器 Selector selector = Selector.open(); // 注册连接服务端socket动作 socketChannel.register(selector, SelectionKey.OP_CONNECT); // 连接 socketChannel.connect(SERVER_ADDRESS); // 分配缓冲区大小内存 Set<SelectionKey> selectionKeys; Iterator<SelectionKey> iterator; SelectionKey selectionKey; SocketChannel client; String receiveText; String sendText; int count=0; while (true) { //选择一组键，其相应的通道已为 I/O 操作准备就绪。 //此方法执行处于阻塞模式的选择操作。 selector.select(); //返回此选择器的已选择键集。 selectionKeys = selector.selectedKeys(); //System.out.println(selectionKeys.size()); iterator = selectionKeys.iterator(); while (iterator.hasNext()) { selectionKey = iterator.next(); if (selectionKey.isConnectable()) { System.out.println("client connect"); client = (SocketChannel) selectionKey.channel(); // 判断此通道上是否正在进行连接操作。 // 完成套接字通道的连接过程。 if (client.isConnectionPending()) { client.finishConnect(); System.out.println("完成连接!"); sendbuffer.clear(); sendbuffer.put("Hello,Server".getBytes()); sendbuffer.flip(); client.write(sendbuffer); } client.register(selector, SelectionKey.OP_READ); } else if (selectionKey.isReadable()) { client = (SocketChannel) selectionKey.channel(); //将缓冲区清空以备下次读取 receivebuffer.clear(); //读取服务器发送来的数据到缓冲区中 count=client.read(receivebuffer); if(count>0){ receiveText = new String( receivebuffer.array(),0,count); System.out.println("客户端接受服务器端数据--:"+receiveText); client.register(selector, SelectionKey.OP_WRITE); } } else if (selectionKey.isWritable()) { sendbuffer.clear(); client = (SocketChannel) selectionKey.channel(); sendText = "message from client--" + (flag++); sendbuffer.put(sendText.getBytes()); //将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位 sendbuffer.flip(); client.write(sendbuffer); System.out.println("客户端向服务器端发送数据--："+sendText); client.register(selector, SelectionKey.OP_READ); } } selectionKeys.clear(); } } } ?
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