netty 简介

Netty一个基于NIO的客户、服务器端的编程框架

1.环境准备

maven依赖

  <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.42.Final</version>
  </dependency>
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RequestMethodEnum 请求方式

public enum RequestMethodEnum {
  GET("GET"),
  POST("POST");
  public String code;
  RequestMethodEnum(String code) {
    this.code=code;
  }}12345678

ParentServlet 父类servlet

public abstract class ParentServlet {
  public void service(ParentRequest request, ParentResponse response) throws Exception {
    //service 方法决定调用doGet、doPost；
    if (RequestMethodEnum.GET.code.equalsIgnoreCase(request.getMethod())) {
      doGet(request, response);
    } else {
      doPost(request, response);
    }
  }
  protected abstract void doPost(ParentRequest request, ParentResponse response) throws Exception;
  protected abstract void doGet(ParentRequest request, ParentResponse response) throws Exception;
}
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1. FirstServlet

public class FirstServlet extends ParentServlet {
  @Override
  protected void doPost(ParentRequest request, ParentResponse response) throws Exception {
    response.write("This is the first");
  }  @Override
  protected void doGet(ParentRequest request, ParentResponse response) throws Exception {
    this.doPost(request,response);
  }}1234567891011

2. SecondServlet

public class SecondServlet extends ParentServlet {
  @Override
  protected void doPost(ParentRequest request, ParentResponse response) throws Exception {
    response.write("this is the second");
  }  @Override
  protected void doGet(ParentRequest request, ParentResponse response) throws Exception {
    this.doPost(request,response);
  }}1234567891011

3. ParentRequest

public class ParentRequest {
  private String method;
  private String url;
  public String getUrl() {
    return url;
  }  public String getMethod() {
    return method;
  }}1234567891011121314

4. ParentResponse

public class ParentResponse {
  private OutputStream out;
  public ParentResponse (OutputStream out) {
    this.out = out;
  }  public void write(String s) throws Exception{
    //输出也要遵循HTTP
    //状态码为200
    StringBuilder sb = new StringBuilder();
    sb.Append("HTTP/1.1 200 OK n")
      .append("Content-Type: text/html;n")
      .append("rn")
      .append(s);
    out.write(sb.toString().getBytes());
  }
}
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5. web.properties

servlet.first.url=/first
servlet.first.className=com.aiden.servlet.FirstServletservlet.second.url=/secondservlet.second.className=com.aiden.servlet.SecondServlet1234

2.基于传统I/O手写Tomcat

1. 修改ParentRequest

public class ParentRequest {
  private String method;
  private String url;
  public ParentRequest(InputStream in) {
    try {
      String content = "";
      byte[] buff = new byte[1024];
      int len = 0;
      if ((len = in.read(buff)) > 0) {
        content = new String(buff,0,len);
      }      String line = content.split("\n")[0];
      String [] arr = line.split("\s");
      this.method = arr[0];
      System.out.println(method);
      this.url = arr[1].split("\?")[0];
    } catch (IOException e) {
      e.printStackTrace();    }  }  public String getUrl() {
    return url;
  }  public String getMethod() {
    return method;
  }}12345678910111213141516171819202122232425262728293031

2. 编写tomcatStart类

public class TomcatStart {
  private int port = 8080;
  private ServerSocket server;
  private Map<String, ParentServlet> servletMapping = new HashMap<String, ParentServlet>();
  private Properties webProperties = new Properties();
  private void init() {
    try {
      String WEB_INF = this.getClass().getResource("/").getPath();
      FileInputStream fis = new FileInputStream(WEB_INF + "web.properties");
      webProperties.load(fis);      for (Object k : webProperties.keySet()) {
        String key = k.toString();
        if (key.endsWith(".url")) {
          String servletName = key.replaceAll("\.url$", "");
          String url = webProperties.getProperty(key);
          String className = webProperties.getProperty(servletName + ".className");
          //单实例  多线程
          ParentServlet obj = (ParentServlet) Class.forName(className).newInstance();
          servletMapping.put(url, obj);
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  public void start() {
    //1.加载配置类，初始化servletMapping
    init();
    try {
      //2.绑定端口启动
      server = new ServerSocket(this.port);
      System.out.println("Tomcat 已启动，监听端口是：" + this.port);
      //3.等待用户请求，用一个死循环
      while (true) {
        Socket client = server.accept();
        //4.http 请求
        process(client);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
  private void process(Socket client) throws IOException {
    InputStream is = null;
    OutputStream os = null;
    try {
      is = client.getInputStream();
      os = client.getOutputStream();
      //5.Request(inputstream) Response (outputstream)
      ParentRequest request = new ParentRequest(is);
      ParentResponse response = new ParentResponse(os);
      //6.从协议内容中获取url 映射相应的servlet
      String url = request.getUrl();
      if (servletMapping.containsKey(url)) {
        //7.调用实例化对象的service方法
        servletMapping.get(url).service(request, response);
      } else {
        response.write("404 - Not Found");
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (os != null) {
        os.flush();
        os.close();
      }
      if (is != null) {
        is.close();
      }
      client.close();
    }
  }
  public static void main(String[] args) {
    //启动
    new TomcatStart().start();
  }
}
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3.基于netty手写Tomcat

1. 修改ParentRequest

public class ParentRequest {
  private ChannelHandlerContext ctx;
  private HttpRequest req;
  public ParentRequest(ChannelHandlerContext ctx, HttpRequest req) {
    this.ctx = ctx;
    this.req = req;
  }  public String getUrl() {
    return req.uri();
  }  public String getMethod() {
    return req.method().name();
  }  public Map<String, List<String>> getParameters() {
    QueryStringDecoder decoder = new QueryStringDecoder(req.uri());
    return decoder.parameters();
  }  public String getParameter(String name) {
    Map<String, List<String>> params = getParameters();
    List<String> param = params.get(name);
    if (null == param) {
      return null;
    } else {
      return param.get(0);
    }  }}123456789101112131415161718192021222324252627282930313233

2. 修改ParentResponse

public class ParentResponse {
  //SocketChannel的封装  private ChannelHandlerContext ctx;  private HttpRequest req;  public ParentResponse(ChannelHandlerContext ctx, HttpRequest req) {    this.ctx = ctx;    this.req = req;  }  public void write(String out) throws Exception {
    try {      if (out == null || out.length() == 0) {
        return;
      }      // 设置 http协议及请求头信息      FullHttpResponse response = new DefaultFullHttpResponse(        // 设置http版本为1.1
        HttpVersion.HTTP_1_1,        // 设置响应状态码        HttpResponseStatus.OK,        // 将输出值写出 编码为UTF-8
        Unpooled.wrappedBuffer(out.getBytes("UTF-8")));
      response.headers().set("Content-Type", "text/html;");
      ctx.write(response);
    } finally {      ctx.flush();
      ctx.close();
    }  }}12345678910111213141516171819202122232425262728293031323334

3. 修改TomcatStart

public class TomcatStart {
  private int port = 8080;
  private Map<String, ParentServlet> servletMapping = new HashMap<String, ParentServlet>();
  private Properties webProperties = new Properties();
  private void init() {
    try {
      String WEB_INF = this.getClass().getResource("/").getPath();
      FileInputStream fis = new FileInputStream(WEB_INF + "web.properties");
      webProperties.load(fis);      for (Object k : webProperties.keySet()) {
        String key = k.toString();
        if (key.endsWith(".url")) {
          String servletName = key.replaceAll("\.url$", "");
          String url = webProperties.getProperty(key);
          String className = webProperties.getProperty(servletName + ".className");
          //单实例  多线程
          ParentServlet obj = (ParentServlet) Class.forName(className).newInstance();
          servletMapping.put(url, obj);
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  public void start() {
    //1.加载配置类，初始化servletMapping
    init();
    // Netty  NIO Reactor模型 Boss Worker
    //Boss 线程
    EventLoopGroup bossGroup = new NioEventLoopGroup();
    //Work线程
    EventLoopGroup workGroup = new NioEventLoopGroup();
    ServerBootstrap server = null;
    try {
      //创建对象
      server = new ServerBootstrap();
      //配置参数
      //链式编程
      server.group(bossGroup, workGroup)
        //主线程处理类，
        .channel(NIOServerSocketChannel.class)
        //子线程处理类
        .childHandler(new ChannelInitializer<SocketChannel>() {
          @Override
          protected void initChannel(SocketChannel client) throws Exception {
            //无锁化串行编程
            //netty对http的封装 对顺序有要求
            //httpResponseEncoder 编码器
            client.pipeline().addLast(new HttpResponseEncoder());
            //httprequestDecoder 解码器
            client.pipeline().addLast(new HttpRequestDecoder());
            //业务处理器
            client.pipeline().addLast(new TomcatHandler());
          }
        })
        //主线程 线程最大数量128
        .option(ChannelOption.SO_BACKLOG, 128)
        //子线程配置 保存长连接
        .childOption(ChannelOption.SO_KEEPALIVE, true);
      ChannelFuture f = server.bind(port).sync();
      System.out.println("Tomcat 已启动，监听端口是：" + this.port);
      f.channel().closeFuture().sync();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      bossGroup.shutdownGracefully();
      workGroup.shutdownGracefully();
    }
  }
  public class TomcatHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
      if (msg instanceof HttpRequest) {
        System.out.println("hello request");
        HttpRequest req = (HttpRequest) msg;
        ParentRequest request = new ParentRequest(ctx, req);
        ParentResponse response = new ParentResponse(ctx, req);
        String url = request.getUrl();
        if (servletMapping.containsKey(url)) {
          //7.调用实例化对象的service方法
          servletMapping.get(url).service(request, response);
        } else {
          response.write("404 - Not Found");
        }
      }
    }
  }
  public static void main(String[] args) {
    //启动
    new TomcatStart().start();
  }
}
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4.访问

http://localhost:8080/first