学习NIO编程，我们首先要了解几个概念：
Buffer（缓冲区）、channel(管道、通道)、selector(选择器、多路复用器)
// 1 基本操作 //创建指定长度的缓冲区 IntBuffer buf = IntBuffer.allocate(10); buf.put(13);// position位置：0 - > 1 buf.put(21);// position位置：1 - > 2 buf.put(35);// position位置：2 - > 3 //把位置复位为0，也就是position位置：3 - > 0 buf.flip(); System.out.println("使用flip复位：" + buf); System.out.println("容量为: " + buf.capacity()); //容量一旦初始化后不允许改变（warp方法包裹数组除外） System.out.println("限制为: " + buf.limit()); //由于只装载了三个元素,所以可读取或者操作的元素为3 则limit=3 System.out.println("获取下标为1的元素：" + buf.get(1)); System.out.println("get(index)方法，position位置不改变：" + buf); buf.put(1, 4); System.out.println("put(index, change)方法，position位置不变：" + buf);; for (int i = 0; i < buf.limit(); i++) { //调用get方法会使其缓冲区位置（position）向后递增一位 System.out.print(buf.get() + "\t"); }
System.out.println("buf对象遍历之后为: " + buf);
buf.flip();
System.out.println(buf);
// wrap方法会包裹一个数组: 一般这种用法不会先初始化缓存对象的长度，因为没有意义，最后还会被wrap所包裹的数组覆盖掉。 // 并且wrap方法修改缓冲区对象的时候，数组本身也会跟着发生变化。 int[] arr = new int[]{1,2,5}; IntBuffer buf1 = IntBuffer.wrap(arr); System.out.println(buf1); IntBuffer buf2 = IntBuffer.wrap(arr, 0 , 2); //这样使用表示容量为数组arr的长度，但是可操作的元素只有实际进入缓存区的元素长度 System.out.println(buf2);
// 3 其他方法 IntBuffer buf1 = IntBuffer.allocate(10); int[] arr = new int[]{1,2,5}; buf1.put(arr); System.out.println(buf1); //一种复制方法 IntBuffer buf3 = buf1.duplicate(); System.out.println(buf3); //设置buf1的位置属性 //buf1.position(0); buf1.flip(); System.out.println(buf1); System.out.println("可读数据为：" + buf1.remaining()); int[] arr2 = new int[buf1.remaining()]; //将缓冲区数据放入arr2数组中去 buf1.get(arr2); for(int i : arr2){ System.out.print(Integer.toString(i) + ","); }
package aio; import java.net.InetSocketAddress; import java.nio.channels.AsynchronousChannelGroup; import java.nio.channels.AsynchronousServerSocketChannel; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class Server { //线程池 private ExecutorService executorService; //线程组 private AsynchronousChannelGroup threadGroup; //服务器通道 public AsynchronousServerSocketChannel assc; public Server(int port){ try { //创建一个缓存池 executorService = Executors.newCachedThreadPool(); //创建线程组，并初始化一个线程池 threadGroup = AsynchronousChannelGroup.withCachedThreadPool(executorService, 1); //创建服务器通道 assc = AsynchronousServerSocketChannel.open(threadGroup); //进行绑定 assc.bind(new InetSocketAddress(port)); System.out.println("server start , port : " + port); //进行阻塞 assc.accept(this, new ServerCompletionHandler()); //一直阻塞 不让服务器停止 Thread.sleep(Integer.MAX_VALUE); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { Server server = new Server(8765); } }
package aio; import java.nio.ByteBuffer; import java.nio.channels.AsynchronousSocketChannel; import java.nio.channels.CompletionHandler; import java.util.concurrent.ExecutionException; public class ServerCompletionHandler implements CompletionHandler<AsynchronousSocketChannel, Server> { @Override public void completed(AsynchronousSocketChannel asc, Server attachment) { //当有下一个客户端接入的时候 直接调用Server的accept方法，这样反复执行下去，保证多个客户端都可以阻塞 attachment.assc.accept(attachment, this); read(asc); } private void read(final AsynchronousSocketChannel asc) { //读取数据 ByteBuffer buf = ByteBuffer.allocate(1024); asc.read(buf, buf, new CompletionHandler<Integer, ByteBuffer>() { @Override public void completed(Integer resultSize, ByteBuffer attachment) { //进行读取之后,重置标识位 attachment.flip(); //获得读取的字节数 System.out.println("Server -> " + "收到客户端的数据长度为:" + resultSize); //获取读取的数据 String resultData = new String(attachment.array()).trim(); System.out.println("Server -> " + "收到客户端的数据信息为:" + resultData); String response = "服务器响应, 收到了客户端发来的数据: " + resultData; write(asc, response); } @Override public void failed(Throwable exc, ByteBuffer attachment) { exc.printStackTrace(); } }); } private void write(AsynchronousSocketChannel asc, String response) { try { ByteBuffer buf = ByteBuffer.allocate(1024); buf.put(response.getBytes()); buf.flip(); asc.write(buf).get(); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } } @Override public void failed(Throwable exc, Server attachment) { exc.printStackTrace(); } }
package aio; import java.io.UnsupportedEncodingException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.AsynchronousSocketChannel; import java.util.concurrent.ExecutionException; public class Client implements Runnable{ private AsynchronousSocketChannel asc ; public Client() throws Exception { asc = AsynchronousSocketChannel.open(); } public void connect(){ asc.connect(new InetSocketAddress("127.0.0.1", 8765)); } public void write(String request){ try { asc.write(ByteBuffer.wrap(request.getBytes())).get(); read(); } catch (Exception e) { e.printStackTrace(); } } private void read() { ByteBuffer buf = ByteBuffer.allocate(1024); try { asc.read(buf).get(); buf.flip(); byte[] respByte = new byte[buf.remaining()]; buf.get(respByte); System.out.println(new String(respByte,"utf-8").trim()); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } @Override public void run() { while(true){ } } public static void main(String[] args) throws Exception { Client c1 = new Client(); c1.connect(); Client c2 = new Client(); c2.connect(); Client c3 = new Client(); c3.connect(); new Thread(c1, "c1").start(); new Thread(c2, "c2").start(); new Thread(c3, "c3").start(); Thread.sleep(1000); c1.write("c1 aaa"); c2.write("c2 bbbb"); c3.write("c3 ccccc"); } }