10.Netty框架的实战使用-支持http协议demo

博客概述

本篇内容结合netty官方给的http协议的例子。基于netty实现了对http协议的支持。通过这个例子对http通讯的netty实现有一些理解，然后会紧接着实现上传下载的案例。打开浏览器，输入http://127.0.0.1:8080/，就可以看到服务器端的影响。

代码实现

服务器端代码

package http;
  
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.util.SelfSignedCertificate;
  
/**
 * An HTTP server that sends back the content of the received HTTP request
 * in a pretty plaintext form.
 */
public final class HttpHelloWorldServer {
    /**
     * 这是对https的支持，如果是http这些就不会生效了
     */
    static final boolean SSL = System.getProperty("ssl") != null;
      static final int PORT = Integer.parseInt(System.getProperty("port", SSL? "8443" : "8080"));
  
      public static void main(String[] args) throws Exception {
          // Configure SSL.
          final SslContext sslCtx;
          if (SSL) {
              SelfSignedCertificate ssc = new SelfSignedCertificate();
              sslCtx = SslContext.newServerContext(ssc.certificate(), ssc.privateKey());
          } else {
              sslCtx = null;
          }
  
          // Configure the server.
          EventLoopGroup bossGroup = new NioEventLoopGroup(1);
          EventLoopGroup workerGroup = new NioEventLoopGroup();
          try {
              ServerBootstrap b = new ServerBootstrap();
              b.option(ChannelOption.SO_BACKLOG, 1024);
              b.group(bossGroup, workerGroup)
               .channel(NioServerSocketChannel.class)
               .handler(new LoggingHandler(LogLevel.INFO))//输出日志
               .childHandler(new HttpHelloWorldServerInitializer(sslCtx));//netty官方的案例对通道建立时处理类做了单独的类处理。
  
              Channel ch = b.bind(PORT).sync().channel();
  
              System.err.println("Open your web browser and navigate to " +
                      (SSL? "https" : "http") + "://127.0.0.1:" + PORT + '/');
  
              ch.closeFuture().sync();
          } finally {
              bossGroup.shutdownGracefully();
              workerGroup.shutdownGracefully();
          }
      }
      
      
}

管道初始化类

  package http;
  
  import io.netty.channel.ChannelInitializer;
  import io.netty.channel.ChannelPipeline;
  import io.netty.channel.socket.SocketChannel;
  import io.netty.handler.codec.http.HttpServerCodec;
  import io.netty.handler.ssl.SslContext;
  
  public class HttpHelloWorldServerInitializer extends ChannelInitializer {
  
      private final SslContext sslCtx;
  
      public HttpHelloWorldServerInitializer(SslContext sslCtx) {
         this.sslCtx = sslCtx;
      }
  
      @Override
      public void initChannel(SocketChannel ch) {
          //ssl安全协议的支持，不配置的话就是http
          ChannelPipeline p = ch.pipeline();
          if (sslCtx != null) {
              p.addLast(sslCtx.newHandler(ch.alloc()));
          }
          //增加对http协议的解码器
          p.addLast(new HttpServerCodec());
          //实现http协议处理的业务类
          p.addLast(new HttpHelloWorldServerHandler());
      }
  }

业务处理handler

package http;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderUtil;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpRequest;
 //静态导入，方便使用一些常量
import static io.netty.handler.codec.http.HttpHeaderNames.*;
import static io.netty.handler.codec.http.HttpResponseStatus.*;
import static io.netty.handler.codec.http.HttpVersion.*;
  
  
  public class HttpHelloWorldServerHandler extends ChannelHandlerAdapter {
      //给页面回写的值
      private static final byte[] CONTENT = { 'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd' };
      /**
       * 功能描述: 监听读取完毕之后的事件，flush写入管道的数据
       *
       * @auther: 李泽
       * @date: 2019/3/18 18:28
       */
      @Override
      public void channelReadComplete(ChannelHandlerContext ctx) {
          ctx.flush();
      }
  
      @Override
      public void channelRead(ChannelHandlerContext ctx, Object msg) {
          if (msg instanceof HttpRequest) {
              HttpRequest req = (HttpRequest) msg;
  
              if (HttpHeaderUtil.is100ContinueExpected(req)) {
                  ctx.write(new DefaultFullHttpResponse(HTTP_1_1, CONTINUE));
              }
              boolean keepAlive = HttpHeaderUtil.isKeepAlive(req);
              //设置响应码，版本和内容
              FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK, Unpooled.wrappedBuffer(CONTENT));
              //设置响应头
              response.headers().set(CONTENT_TYPE, "text/plain");
              response.headers().setInt(CONTENT_LENGTH, response.content().readableBytes());
              //根据该字段决定是否保持连接，只写入数据，由channelReadComplete统一冲刷
              if (!keepAlive) {
                  ctx.write(response).addListener(ChannelFutureListener.CLOSE);
              } else {
                  response.headers().set(CONNECTION, HttpHeaderValues.KEEP_ALIVE);
                  ctx.write(response);
              }
          }
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
          cause.printStackTrace();
          ctx.close();
      }
  }