Java 网络IO编程总结（BIO、NIO、AIO均含完整实例代码）

import java.io.IOException;  

import java.io.UnsupportedEncodingException;  

import java.nio.ByteBuffer;  

import java.nio.channels.AsynchronousSocketChannel;  

import java.nio.channels.CompletionHandler;  

import com.anxpp.io.utils.Calculator;  

public class ReadHandler implements CompletionHandler<Integer, ByteBuffer> {  

    //用于读取半包消息和发送应答  

    private AsynchronousSocketChannel channel;  

    public ReadHandler(AsynchronousSocketChannel channel) {  

            this.channel = channel;  

    }  

    //读取到消息后的处理  

    @Override  

    public void completed(Integer result, ByteBuffer attachment) {  

        //flip操作  

        attachment.flip();  

        //根据  

        byte[] message = new byte[attachment.remaining()];  

        attachment.get(message);  

        try {  

            String expression = new String(message, "UTF-8");  

            System.out.println("服务器收到消息: " + expression);  

            String calrResult = null;  

            try{  

                calrResult = Calculator.cal(expression).toString();  

            }catch(Exception e){  

                calrResult = "计算错误：" + e.getMessage();  

            }  

            //向客户端发送消息  

            doWrite(calrResult);  

        } catch (UnsupportedEncodingException e) {  

            e.printStackTrace();  

        }  

    }  

    //发送消息  

    private void doWrite(String result) {  

        byte[] bytes = result.getBytes();  

        ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);  

        writeBuffer.put(bytes);  

        writeBuffer.flip();  

        //异步写数据 参数与前面的read一样  

        channel.write(writeBuffer, writeBuffer,new CompletionHandler<Integer, ByteBuffer>() {  

            @Override  

            public void completed(Integer result, ByteBuffer buffer) {  

                //如果没有发送完，就继续发送直到完成  

                if (buffer.hasRemaining())  

                    channel.write(buffer, buffer, this);  

                else{  

                    //创建新的Buffer  

                    ByteBuffer readBuffer = ByteBuffer.allocate(1024);  

                    //异步读  第三个参数为接收消息回调的业务Handler  

                    channel.read(readBuffer, readBuffer, new ReadHandler(channel));  

                }  

            }  

            @Override  

            public void failed(Throwable exc, ByteBuffer attachment) {  

                try {  

                    channel.close();  

                } catch (IOException e) {  

                }  

            }  

        });  

    }  

    @Override  

    public void failed(Throwable exc, ByteBuffer attachment) {  

        try {  

            this.channel.close();  

        } catch (IOException e) {  

            e.printStackTrace();  

        }  

    }  

}