深入刨析tomcat 之---第9篇 how tomcat works 第9章,Session的实现关于request.setContext(context)

writedby 张艳涛,在学第9章session的时候,做了个实验在给的demo代码中添加了

package com.zyt.tomcat.ex09.core;

public class SimpleWrapperValve implements Valve, Contained {

    protected Container container;

    public void invoke(Request request, Response response, ValveContext valveContext)

            throws IOException, ServletException {

        SimpleWrapper wrapper = (SimpleWrapper) getContainer();

        ServletRequest sreq = request.getRequest();

        ServletResponse sres = response.getResponse();

        Servlet servlet = null;

        HttpServletRequest hreq = null;

        if (sreq instanceof HttpServletRequest)

            hreq = (HttpServletRequest) sreq;

        HttpServletResponse hres = null;

        if (sres instanceof HttpServletResponse)

            hres = (HttpServletResponse) sres;

        //-- new addition -----------------------------------

        Context context = (Context) wrapper.getParent();

        request.setContext(context);

        //-------------------------------------

        // Allocate a servlet instance to process this request

        try {

            servlet = wrapper.allocate();

            if (hres!=null && hreq!=null) {

                servlet.service(hreq, hres);

            }

            else {

                servlet.service(sreq, sres);

            }

        }

        catch (ServletException e) {

        }

    }

    public String getInfo() {

        return null;

    }

    public Container getContainer() {

        return container;

    }

    public void setContainer(Container container) {

        this.container = container;

    }

}

当看看11章的时候,使用 StandardWrapper,再次调用

        System.setProperty("catalina.base", System.getProperty("user.dir"));

        HttpConnector connector = new HttpConnector();

        StandardWrapper wrapper1 = new StandardWrapper();

        wrapper1.setName("Primitive");

        wrapper1.setServletClass("PrimitiveServlet");

        wrapper1.setDebug(2);

        StandardWrapper wrapper2 = new StandardWrapper();

        wrapper2.setName("Modern");

        wrapper2.setServletClass("ModernServlet");

        wrapper2.setDebug(2);

        Wrapper wrapper3 = new StandardWrapper();

        wrapper3.setName("SessionZYT");

        wrapper3.setServletClass("SessionServletZYT");

        //wrapper3.setDebug(2);

        Context context= new StandardContext();

        context.setPath("/myApp");

        context.setDocBase("myApp");

        LifecycleListener listener = new SimpleContextConfig();

        ((Lifecycle) context).addLifecycleListener(listener);

        context.addChild(wrapper1);

        context.addChild(wrapper2);

        context.addChild(wrapper3);

        context.addServletMapping("/myApp/SessionZYT","SessionZYT");

这是如果你调用/myApp/SessionZYT 会报错,追随代码的时候发现了request对象没有context成员变量,所以

SessionServletZYT 类编译了,放在app目录下

import javax.servlet.ServletException;

import javax.servlet.SingleThreadModel;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import java.io.IOException;

import java.io.PrintWriter;

public class SessionServletZYT extends HttpServlet implements SingleThreadModel {

  public void doGet(HttpServletRequest request, HttpServletResponse response)

    throws ServletException, IOException {

    System.out.println("SessionServlet -- service");

    response.setContentType("text/html");

    PrintWriter out = response.getWriter();

    out.println("<html>");

    out.println("<head><title>SessionServlet</title></head>");

    out.println("<body>");

    String value = request.getParameter("value");

    HttpSession session = request.getSession(true);

    out.println("<br>the previous value is " +

      (String) session.getAttribute("value"));

    out.println("<br>the current value is " + value);

    session.setAttribute("value", value);

    out.println("<br><hr>");

    out.println("<form>");

    out.println("New Value: <input name=value>");

    out.println("<input type=submit>");

    out.println("</form>");

    out.println("</body>");

    out.println("</html>");

  }

}

这句报错,要通过request.getContext() -->再次context.getManager(),查了半天也没答案,所以看到13章host就找到了设置的地方了

StandardHostMapper类中

    public Container map(Request request, boolean update) {

        // Has this request already been mapped?

        if (update && (request.getContext() != null))

            return (request.getContext());

        // Perform mapping on our request URI

        String uri = ((HttpRequest) request).getDecodedRequestURI();

        Context context = host.map(uri);

        // Update the request (if requested) and return the selected Context

        if (update) {

            request.setContext(context);

            if (context != null)

                ((HttpRequest) request).setContextPath(context.getPath());

            else

                ((HttpRequest) request).setContextPath(null);

        }

        return (context);

    }

标记的就是给request 设置了context的了

巴特西

深入刨析tomcat 之---第9篇 how tomcat works 第9章,Session的实现关于request.setContext(context)

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巴特西

深入刨析tomcat 之---第9篇 how tomcat works 第9章,Session的实现 关于request.setContext(context)

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深入刨析tomcat 之---第9篇 how tomcat works 第9章,Session的实现关于request.setContext(context)