Netty4.0学习笔记系列之三：构建简单的http服务

浏览数：40 / 时间：2015年06月09日

http://blog.csdn.net/u013252773/article/details/21254257

本文主要介绍如何通过Netty构建一个简单的http服务。

想要实现的目的是：

1、Client向Server发送http请求。

2、Server端对http请求进行解析。

3、Server端向client发送http响应。

4、Client对http响应进行解析。

在该实例中，会涉及到http请求的编码、解码，http响应的编码、解码，幸运的是，Netty已经为我们提供了这些工具，整个实例的逻辑图如下所示：

其中红色框中的4个类是Netty提供的，它们其实也是一种Handler，其中Encoder继承自ChannelOutboundHandler，Decoder继承自ChannelInboundHandler，它们的作用是：

1、HttpRequestEncoder：对httpRequest进行编码。

2、HttpRequestDecoder：把流数据解析为httpRequest。

3、HttpResponsetEncoder：对httpResponset进行编码。

4、HttpResponseEncoder：把流数据解析为httpResponse。

该实例涉及到的类有5个：HttpServer HttpServerInboundHandler HttpClient HttpClientInboundHandler ByteBufToBytes

1、HttpServer 启动http服务器

[java] view plain copy

package com.guowl.testhttpprotocol;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpRequestDecoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
public class HttpServer {
public void start(int port) throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap(); // (2)
b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) // (3)
.childHandler(new ChannelInitializer<SocketChannel>() { // (4)
@Override
public void initChannel(SocketChannel ch) throws Exception {
// server端发送的是httpResponse，所以要使用HttpResponseEncoder进行编码
ch.pipeline().addLast(new HttpResponseEncoder());
// server端接收到的是httpRequest，所以要使用HttpRequestDecoder进行解码
ch.pipeline().addLast(new HttpRequestDecoder());
ch.pipeline().addLast(new HttpServerInboundHandler());
}
}).option(ChannelOption.SO_BACKLOG, 128) // (5)
.childOption(ChannelOption.SO_KEEPALIVE, true); // (6)
ChannelFuture f = b.bind(port).sync(); // (7)
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
HttpServer server = new HttpServer();
server.start(8000);
}
}

2、HttpServerInboundHandler 解析客户端的请求，并进行响应

[java] view plain copy

package com.guowl.testhttpprotocol;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONNECTION;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_LENGTH;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_TYPE;
import static io.netty.handler.codec.http.HttpResponseStatus.OK;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpContent;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpHeaders.Values;
import io.netty.handler.codec.http.HttpRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.guowl.utils.ByteBufToBytes;
public class HttpServerInboundHandler extends ChannelInboundHandlerAdapter {
private static Logger logger = LoggerFactory.getLogger(HttpServerInboundHandler.class);
private ByteBufToBytes reader;
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (msg instanceof HttpRequest) {
HttpRequest request = (HttpRequest) msg;
System.out.println("messageType:" + request.headers().get("messageType"));
System.out.println("businessType:" + request.headers().get("businessType"));
if (HttpHeaders.isContentLengthSet(request)) {
reader = new ByteBufToBytes((int) HttpHeaders.getContentLength(request));
}
}
if (msg instanceof HttpContent) {
HttpContent httpContent = (HttpContent) msg;
ByteBuf content = httpContent.content();
reader.reading(content);
content.release();
if (reader.isEnd()) {
String resultStr = new String(reader.readFull());
System.out.println("Client said:" + resultStr);
FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK, Unpooled.wrappedBuffer("I am ok"
.getBytes()));
response.headers().set(CONTENT_TYPE, "text/plain");
response.headers().set(CONTENT_LENGTH, response.content().readableBytes());
response.headers().set(CONNECTION, Values.KEEP_ALIVE);
ctx.write(response);
ctx.flush();
}
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
logger.info("HttpServerInboundHandler.channelReadComplete");
ctx.flush();
}
}

3、HttpClient 向服务器发送请求

[java] view plain copy

package com.guowl.testhttpprotocol;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.DefaultFullHttpRequest;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpRequestEncoder;
import io.netty.handler.codec.http.HttpResponseDecoder;
import io.netty.handler.codec.http.HttpVersion;
import java.net.URI;
public class HttpClient {
public void connect(String host, int port) throws Exception {
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap(); // (1)
b.group(workerGroup); // (2)
b.channel(NioSocketChannel.class); // (3)
b.option(ChannelOption.SO_KEEPALIVE, true); // (4)
b.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
// 客户端接收到的是httpResponse响应，所以要使用HttpResponseDecoder进行解码
ch.pipeline().addLast(new HttpResponseDecoder());
// 客户端发送的是httprequest，所以要使用HttpRequestEncoder进行编码
ch.pipeline().addLast(new HttpRequestEncoder());
ch.pipeline().addLast(new HttpClientInboundHandler());
}
});
// Start the client.
ChannelFuture f = b.connect(host, port).sync(); // (5)
URI uri = new URI("http://127.0.0.1:8000");
String msg = "Are you ok?";
DefaultFullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.POST,
uri.toASCIIString(), Unpooled.wrappedBuffer(msg.getBytes()));
// 构建http请求
request.headers().set(HttpHeaders.Names.HOST, host);
request.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
request.headers().set(HttpHeaders.Names.CONTENT_LENGTH, request.content().readableBytes());
request.headers().set("messageType", "normal");
request.headers().set("businessType", "testServerState");
// 发送http请求
f.channel().write(request);
f.channel().flush();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
HttpClient client = new HttpClient();
client.connect("127.0.0.1", 8000);
}
}

4、HttpClientInboundHandler 对服务器的响应进行读取

[java] view plain copy

package com.guowl.testhttpprotocol;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.HttpContent;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpResponse;
import com.guowl.utils.ByteBufToBytes;
public class HttpClientInboundHandler extends ChannelInboundHandlerAdapter {
private ByteBufToBytes reader;
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (msg instanceof HttpResponse) {
HttpResponse response = (HttpResponse) msg;
System.out.println("CONTENT_TYPE:" + response.headers().get(HttpHeaders.Names.CONTENT_TYPE));
if (HttpHeaders.isContentLengthSet(response)) {
reader = new ByteBufToBytes((int) HttpHeaders.getContentLength(response));
}
}
if (msg instanceof HttpContent) {
HttpContent httpContent = (HttpContent) msg;
ByteBuf content = httpContent.content();
reader.reading(content);
content.release();
if (reader.isEnd()) {
String resultStr = new String(reader.readFull());
System.out.println("Server said:" + resultStr);
ctx.close();
}
}
}
}