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HTTP 是基于请求/响应模式的：客户端向服务器发送一个 HTTP 请求，然后服务器将会返回一个 HTTP 响应。Netty 提供了多种编码器和解码器以简化对这个协议的使用。一个HTTP 请求/响应可能由多个数据部分组成，FullHttpRequest 和FullHttpResponse 消息是特殊的子类型，分别代表了完整的请求和响应。所有类型的 HTTP 消息（FullHttpRequest、LastHttpContent 等等）都实现了 HttpObject 接口。
(1) HttpRequestEncoder 将 HttpRequest、HttpContent 和 LastHttpContent 消息编码为字节。 (2) HttpResponseEncoder 将 HttpResponse、HttpContent 和 LastHttpContent 消息编码为字节。 (3) HttpRequestDecoder 将字节解码为 HttpRequest、HttpContent 和 LastHttpContent 消息。 (4) HttpResponseDecoder 将字节解码为 HttpResponse、HttpContent 和 LastHttpContent 消息。 (5) HttpClientCodec 和 HttpServerCodec 则将请求和响应做了一个组合。
由于 HTTP 的请求和响应可能由许多部分组成，因此你需要聚合它们以形成完整的消息。
为了消除这项繁琐的任务，Netty 提供了一个聚合器 HttpObjectAggregator，它可以将多个消
息部分合并为 FullHttpRequest 或者 FullHttpResponse 消息。通过这样的方式，你将总是看
到完整的消息内容。
当使用 HTTP 时，建议开启压缩功能以尽可能多地减小传输数据的大小。虽然压缩会带
来一些 CPU 时钟周期上的开销，但是通常来说它都是一个好主意，特别是对于文本数据来
说。Netty 为压缩和解压缩提供了 ChannelHandler 实现，它们同时支持 gzip 和 deflate 编码。
<dependencies>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.28.Final</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.20</version>
<scope>provided</scope>
</dependency>
<!--工具-->
<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>4.4</version>
</dependency>
<!--日志-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.21</version>
</dependency>
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.6.2</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.25</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>8</source>
<target>8</target>
</configuration>
</plugin>
</plugins>
</build>public class HttpConsts {
private HttpConsts() {
}
public static final Integer PORT = 8888;
public static final String HOST = "127.0.0.1";
}2.3.1 HttpServer
@Slf4j
public class HttpServer {
public static void main(String[] args) throws InterruptedException {
HttpServer httpServer = new HttpServer();
httpServer.start();
}
public void start() throws InterruptedException {
EventLoopGroup boss = new NioEventLoopGroup(1);
EventLoopGroup worker = new NioEventLoopGroup();
try {
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(boss, worker)
.channel(NioServerSocketChannel.class)
.childHandler(new HttpServerHandlerInitial());
ChannelFuture channelFuture = serverBootstrap.bind(HttpConsts.PORT).sync();
log.info("服务器已开启......");
channelFuture.channel().closeFuture().sync();
} finally {
boss.shutdownGracefully();
worker.shutdownGracefully();
}
}
}2.3.2 HttpServerBusinessHandler
@Slf4j
public class HttpServerBusinessHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
//通过编解码器把byteBuf解析成FullHttpRequest
if (msg instanceof FullHttpRequest) {
//获取httpRequest
FullHttpRequest httpRequest = (FullHttpRequest) msg;
try {
//获取请求路径、请求体、请求方法
String uri = httpRequest.uri();
String content = httpRequest.content().toString(CharsetUtil.UTF_8);
HttpMethod method = httpRequest.method();
log.info("服务器接收到请求:");
log.info("请求uri:{},请求content:{},请求method:{}", uri, content, method);
//响应
String responseMsg = "Hello World";
FullHttpResponse response = new DefaultFullHttpResponse(
HttpVersion.HTTP_1_1,HttpResponseStatus.OK,
Unpooled.copiedBuffer(responseMsg,CharsetUtil.UTF_8)
);
response.headers().set(HttpHeaderNames.CONTENT_TYPE,"text/plain;charset=UTF-8");
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
} finally {
httpRequest.release();
}
}
}
}2.3.3 HttpServerHandlerInitial
public class HttpServerHandlerInitial extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//http请求编解码器,请求解码，响应编码
pipeline.addLast("serverCodec", new HttpServerCodec());
//http请求报文聚合为完整报文，最大请求报文为10M
pipeline.addLast("aggregator", new HttpObjectAggregator(10 * 1024 * 1024));
//响应报文压缩
pipeline.addLast("compress", new HttpContentCompressor());
//业务处理handler
pipeline.addLast("serverBusinessHandler", new HttpServerBusinessHandler());
}
}2.4.1 HttpClient
public class HttpClient {
public static void main(String[] args) throws InterruptedException {
HttpClient httpClien = new HttpClient();
httpClien.start();
}
public void start() throws InterruptedException {
EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(eventLoopGroup)
.channel(NioSocketChannel.class)
.handler(new HttpClientHandlerInitial());
ChannelFuture f = bootstrap.connect(HttpConsts.HOST, HttpConsts.PORT).sync();
f.channel().closeFuture().sync();
} finally {
eventLoopGroup.shutdownGracefully();
}
}
}2.4.2 HttpClientBusinessHandler
@Slf4j
public class HttpClientBusinessHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
//通过编解码器把byteBuf解析成FullHttpResponse
if (msg instanceof FullHttpResponse) {
FullHttpResponse httpResponse = (FullHttpResponse) msg;
HttpResponseStatus status = httpResponse.status();
ByteBuf content = httpResponse.content();
log.info("客户端接收响应信息：");
log.info("status:{},content:{}", status, content.toString(CharsetUtil.UTF_8));
httpResponse.release();
}
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
//封装请求信息
URI uri = new URI("/test");
String msg = "Hello";
DefaultFullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1,
HttpMethod.GET, uri.toASCIIString(), Unpooled.wrappedBuffer(msg.getBytes(CharsetUtil.UTF_8)));
//构建http请求
request.headers().set(HttpHeaderNames.HOST, HttpConsts.HOST);
request.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
request.headers().set(HttpHeaderNames.CONTENT_LENGTH, request.content().readableBytes());
// 发送http请求
ctx.writeAndFlush(request);
}
}2.4.3 HttpClientHandlerInitial
public class HttpClientHandlerInitial extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//客户端编码、解码器，请求编码，响应解码
pipeline.addLast("clientCodec", new HttpClientCodec());
//http聚合器，将http请求聚合成一个完整报文
pipeline.addLast("aggregator", new HttpObjectAggregator(10 * 1024 * 1024));
//http响应解压缩
pipeline.addLast("decompressor", new HttpContentDecompressor());
//业务handler
pipeline.addLast("clientBusinessHandler", new HttpClientBusinessHandler());
}
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