在上一篇文章中《Android 基于Netty的消息推送方案之概念和工作原理(二)》 ，我们介绍过一些关于Netty的概念和工作原理的内容，今天我们先来介绍一个叫做ChannelBuffer的东东。
ChannelBuffer
Netty中的消息传递，都必须以字节的形式，以ChannelBuffer为载体传递。简单的说，就是你想直接写个字符串过去，对不起，抛异常。虽然，Netty定义的writer的接口参数是Object的，这可能也是会给新上手的朋友容易造成误会的地方。Netty源码中，是这样判断的。
- SendBuffer acquire(Object message) {
- if (message instanceof ChannelBuffer) {
- return acquire((ChannelBuffer) message);
- } else if (message instanceof FileRegion) {
- return acquire((FileRegion) message);
- }
-
- throw new IllegalArgumentException(
- "unsupported message type: " + message.getClass());
- }
接下来我们写一个Demo来学习它。
服务端代码如下
- public class MessageServer {
- public static void main(String args[]){
-
- ServerBootstrap bootstrap = new ServerBootstrap(new NioServerSocketChannelFactory(Executors.newCachedThreadPool(),Executors.newCachedThreadPool()));
-
- bootstrap.setPipelineFactory(new ChannelPipelineFactory(){
- @Override
- public ChannelPipeline getPipeline() throws Exception {
- return Channels.pipeline(new BusinessHandler());
- }
- });
-
- bootstrap.bind(new InetSocketAddress(8000));
- }
-
- private static class BusinessHandler extends SimpleChannelHandler{
-
- @Override
- public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
- ChannelBuffer buffer = (ChannelBuffer)e.getMessage();
- System.out.println("Receive:"+buffer.toString(Charset.defaultCharset()));
- String msg = buffer.toString(Charset.defaultCharset()) + "has been processed!";
- ChannelBuffer buffer2 = ChannelBuffers.buffer(msg.length());
- buffer2.writeBytes(msg.getBytes());
- e.getChannel().write(buffer2);
- }
- }
- }
客户端代码如下
- public class MessageClient {
- public static void main(String args[]) {
- ClientBootstrap bootstrap = new ClientBootstrap(new NioClientSocketChannelFactory(Executors.newCachedThreadPool(), Executors.newCachedThreadPool()));
-
- bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
- @Override
- public ChannelPipeline getPipeline() throws Exception {
- return Channels.pipeline(new MessageClientHandler());
- }
- });
- bootstrap.connect(new InetSocketAddress("127.0.0.1", 8000));
- }
-
- private static class MessageClientHandler extends SimpleChannelHandler {
-
- @Override
- public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
-
- String msg = "Hello, I‘m client.";
- ChannelBuffer buffer = ChannelBuffers.buffer(msg.length());
- buffer.writeBytes(msg.getBytes());
- e.getChannel().write(buffer);
- }
- }
- }
先启动服务端，再启动客户端，可以看到服务端打印如下字符串
- Receive:Hello, I‘m client.
如果你感兴趣，请继续阅读《Android 基于Netty的消息推送方案之对象的传递（四）》
Android 基于Netty的消息推送方案之字符串的接收和发送（三）
原文：http://www.cnblogs.com/dongweiq/p/4019439.html
