Callback 入门例子
代码
- TestServer
[java]
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34package com.github.houbb.netty.inaction.components.callback;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
public class TestServer {
public static void main(String[] args) throws Exception{
/**
* 死循环 线程组
* NioEventLoopGroup 是用来处理I/O操作的线程池，Netty对 EventLoopGroup 接口针对不同的传输协议提供了不同的实现。
* 在本例子中，需要实例化两个NioEventLoopGroup，通常第一个称为“boss”，
* 用来accept客户端连接，另一个称为“worker”，处理客户端数据的读写操作。
*/
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try{
//启动服务端的类 ServerBootstrap 是启动服务的辅助类，有关socket的参数可以通过ServerBootstrap进行设置。
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)//这里指定NioServerSocketChannel类初始化channel用来接受客户端请求。
.childHandler(new TestServerInitializer());
ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
System.out.println("Netty Server listen on: 8899");
channelFuture.channel().closeFuture().sync();
}finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
- 建一个Initializer
[java]
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17package com.github.houbb.netty.inaction.components.callback;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;
//通常会为新SocketChannel通过添加一些handler，来设置ChannelPipeline。
public class TestServerInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("httpServiceCodec",new HttpServerCodec());//netty自己的处理器
pipeline.addLast("testHttpServerHandler",new TestHttpServerHandler());//自定义的处理器
}
}
- TestHttpServerHandler.java
[java]
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75package com.github.houbb.netty.inaction.components.callback;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.*;
import io.netty.util.CharsetUtil;
import java.net.URI;
public class TestHttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {
/**
* SpringMVC由容器来判断http请求是否结束了 netty可以自己判断keepalive
* @param ctx
* @param msg
* @throws Exception
*/
@Override
protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
System.out.println(msg.getClass());
System.out.println(ctx.channel().remoteAddress());
// Thread.sleep(8000);
if (msg instanceof HttpRequest) {
HttpRequest httpRequest = (HttpRequest) msg;
System.out.println("请求方法名:" + httpRequest.method().name());
URI uri = new URI(httpRequest.uri());
if ("/favicon.ico".equals(uri.getPath())) {
System.out.println("请求favicon.ico");
return;
}
//读取客户端的请求并返回响应
ByteBuf content = Unpooled.copiedBuffer("Hello World", CharsetUtil.UTF_8);
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, content);
response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain");
response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());
ctx.writeAndFlush(response);
ctx.channel().close();
}
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("channerl active");
super.channelActive(ctx);
}
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("channelRegistered");
super.channelRegistered(ctx);
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
System.out.println("handlerAdded");
super.handlerAdded(ctx);
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("channelInactive");
super.channelInactive(ctx);
}
@Override
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("channelUnregistered");
super.channelUnregistered(ctx);
}
}
测试
curl
命令行执行
[plaintext]
1curl 'http://localhost:8899'
命令行信息如下：
[plaintext]
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10handlerAdded 一个新的handler添加 新的通道
channelRegistered 注册到某个对象
channerl active 连接处于活动状态
class io.netty.handler.codec.http.DefaultHttpRequest
/0:0:0:0:0:0:0:1:60290
请求方法名:GET 请求读取
class io.netty.handler.codec.http.LastHttpContent$1
/0:0:0:0:0:0:0:1:60290
channelInactive 变成不活动状态
channelUnregistered 取消注册
浏览器
如果使用浏览器来请求 http://localhost:8899 则有所不同
[plaintext]
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14handlerAdded
channelRegistered
channerl active
class io.netty.handler.codec.http.DefaultHttpRequest
/0:0:0:0:0:0:0:1:60322
请求方法名:GET
class io.netty.handler.codec.http.LastHttpContent$1
/0:0:0:0:0:0:0:1:60322
class io.netty.handler.codec.http.DefaultHttpRequest
/0:0:0:0:0:0:0:1:60322
请求方法名:GET
请求favicon.ico
class io.netty.handler.codec.http.LastHttpContent$1
/0:0:0:0:0:0:0:1:60322
状态失效
可以看到并没有出现
[plaintext]
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2channelInactive
channelUnregistered
当我们把浏览器关闭之后，这两行才出现，这里也体现了Netty并没有遵循Servlet规范，需要自己实现。
我们平时的SpringMVC应用运行在tomcat之上，与http请求之间的连接由tomcat来保证相应的连接断掉，但是Netty不是这样的。
