StandardWrapper中的加载servlet方法
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StandardWrapper
/** * Load and initialize an instance of this servlet, if there is not already * at least one initialized instance. This can be used, for example, to * load servlets that are marked in the deployment descriptor to be loaded * at server startup time. */ public synchronized Servlet loadServlet() throws ServletException { // Nothing to do if we already have an instance or an instance pool if (!singleThreadModel && (instance != null)) return instance; PrintStream out = System.out; if (swallowOutput) { SystemLogHandler.startCapture(); } Servlet servlet; try { long t1=System.currentTimeMillis(); // If this "servlet" is really a JSP file, get the right class. // HOLD YOUR NOSE - this is a kludge that avoids having to do special // case Catalina-specific code in Jasper - it also requires that the // servlet path be replaced by the <jsp-file> element content in // order to be completely effective String actualClass = servletClass; if ((actualClass == null) && (jspFile != null)) { Wrapper jspWrapper = (Wrapper) ((Context) getParent()).findChild(Constants.JSP_SERVLET_NAME); if (jspWrapper != null) { actualClass = jspWrapper.getServletClass(); // Merge init parameters String paramNames[] = jspWrapper.findInitParameters(); for (int i = 0; i < paramNames.length; i++) { if (parameters.get(paramNames[i]) == null) { parameters.put (paramNames[i], jspWrapper.findInitParameter(paramNames[i])); } } } } // Complain if no servlet class has been specified if (actualClass == null) { unavailable(null); throw new ServletException (sm.getString("standardWrapper.notClass", getName())); } // Acquire an instance of the class loader to be used Loader loader = getLoader(); if (loader == null) { unavailable(null); throw new ServletException (sm.getString("standardWrapper.missingLoader", getName())); } ClassLoader classLoader = loader.getClassLoader(); // Special case class loader for a container provided servlet // if (isContainerProvidedServlet(actualClass) && ! ((Context)getParent()).getPrivileged() ) { // If it is a priviledged context - using its own // class loader will work, since it's a child of the container // loader classLoader = this.getClass().getClassLoader(); } // Load the specified servlet class from the appropriate class loader Class classClass = null; try { if (System.getSecurityManager() != null){ final ClassLoader fclassLoader = classLoader; final String factualClass = actualClass; try{ classClass = (Class)AccessController.doPrivileged( new PrivilegedExceptionAction(){ public Object run() throws Exception{ if (fclassLoader != null) { return fclassLoader.loadClass(factualClass); } else { return Class.forName(factualClass); } } }); } catch(PrivilegedActionException pax){ Exception ex = pax.getException(); if (ex instanceof ClassNotFoundException){ throw (ClassNotFoundException)ex; } else { getServletContext().log( "Error loading " + fclassLoader + " " + factualClass, ex ); } } } else { if (classLoader != null) { classClass = classLoader.loadClass(actualClass); } else { classClass = Class.forName(actualClass); } } } catch (ClassNotFoundException e) { unavailable(null); getServletContext().log( "Error loading " + classLoader + " " + actualClass, e ); throw new ServletException (sm.getString("standardWrapper.missingClass", actualClass), e); } if (classClass == null) { unavailable(null); throw new ServletException (sm.getString("standardWrapper.missingClass", actualClass)); } // Instantiate and initialize an instance of the servlet class itself try { servlet = (Servlet) classClass.newInstance(); } catch (ClassCastException e) { unavailable(null); // Restore the context ClassLoader throw new ServletException (sm.getString("standardWrapper.notServlet", actualClass), e); } catch (Throwable e) { unavailable(null); // Restore the context ClassLoader throw new ServletException (sm.getString("standardWrapper.instantiate", actualClass), e); } // Check if loading the servlet in this web application should be // allowed if (!isServletAllowed(servlet)) { throw new SecurityException (sm.getString("standardWrapper.privilegedServlet", actualClass)); } // Special handling for ContainerServlet instances if ((servlet instanceof ContainerServlet) && (isContainerProvidedServlet(actualClass) || ((Context)getParent()).getPrivileged() )) { ((ContainerServlet) servlet).setWrapper(this); } classLoadTime=(int) (System.currentTimeMillis() -t1); // Call the initialization method of this servlet try { instanceSupport.fireInstanceEvent(InstanceEvent.BEFORE_INIT_EVENT, servlet); if( System.getSecurityManager() != null) { Class[] classType = new Class[]{ServletConfig.class}; Object[] args = new Object[]{((ServletConfig)facade)}; SecurityUtil.doAsPrivilege("init", servlet, classType, args); } else { servlet.init(facade); } // Invoke jspInit on JSP pages if ((loadOnStartup >= 0) && (jspFile != null)) { // Invoking jspInit DummyRequest req = new DummyRequest(); req.setServletPath(jspFile); req.setQueryString("jsp_precompile=true"); DummyResponse res = new DummyResponse(); if( System.getSecurityManager() != null) { Class[] classType = new Class[]{ServletRequest.class, ServletResponse.class}; Object[] args = new Object[]{req, res}; SecurityUtil.doAsPrivilege("service", servlet, classType, args); } else { servlet.service(req, res); } } instanceSupport.fireInstanceEvent(InstanceEvent.AFTER_INIT_EVENT, servlet); } catch (UnavailableException f) { instanceSupport.fireInstanceEvent(InstanceEvent.AFTER_INIT_EVENT, servlet, f); unavailable(f); throw f; } catch (ServletException f) { instanceSupport.fireInstanceEvent(InstanceEvent.AFTER_INIT_EVENT, servlet, f); // If the servlet wanted to be unavailable it would have // said so, so do not call unavailable(null). throw f; } catch (Throwable f) { getServletContext().log("StandardWrapper.Throwable", f ); instanceSupport.fireInstanceEvent(InstanceEvent.AFTER_INIT_EVENT, servlet, f); // If the servlet wanted to be unavailable it would have // said so, so do not call unavailable(null). throw new ServletException (sm.getString("standardWrapper.initException", getName()), f); } // Register our newly initialized instance singleThreadModel = servlet instanceof SingleThreadModel; if (singleThreadModel) { if (instancePool == null) instancePool = new Stack(); } fireContainerEvent("load", this); loadTime=System.currentTimeMillis() -t1; } finally { if (swallowOutput) { String log = SystemLogHandler.stopCapture(); if (log != null && log.length() > 0) { if (getServletContext() != null) { getServletContext().log(log); } else { out.println(log); } } } } return servlet; } /** * Unload all initialized instances of this servlet, after calling the * <code>destroy()</code> method for each instance. This can be used, * for example, prior to shutting down the entire servlet engine, or * prior to reloading all of the classes from the Loader associated with * our Loader's repository. * * @exception ServletException if an exception is thrown by the * destroy() method */ public synchronized void unload() throws ServletException { // Nothing to do if we have never loaded the instance if (!singleThreadModel && (instance == null)) return; unloading = true; // Loaf a while if the current instance is allocated // (possibly more than once if non-STM) if (countAllocated > 0) { int nRetries = 0; while ((nRetries < 21) && (countAllocated > 0)) { if ((nRetries % 10) == 0) { log.info(sm.getString("standardWrapper.waiting", new Integer(countAllocated))); } try { Thread.sleep(100); } catch (InterruptedException e) { ; } nRetries++; } } ClassLoader oldCtxClassLoader = Thread.currentThread().getContextClassLoader(); ClassLoader classLoader = instance.getClass().getClassLoader(); PrintStream out = System.out; if (swallowOutput) { SystemLogHandler.startCapture(); } // Call the servlet destroy() method try { instanceSupport.fireInstanceEvent (InstanceEvent.BEFORE_DESTROY_EVENT, instance); Thread.currentThread().setContextClassLoader(classLoader); if( System.getSecurityManager() != null) { SecurityUtil.doAsPrivilege("destroy", instance); SecurityUtil.remove(instance); } else { instance.destroy(); } instanceSupport.fireInstanceEvent (InstanceEvent.AFTER_DESTROY_EVENT, instance); } catch (Throwable t) { instanceSupport.fireInstanceEvent (InstanceEvent.AFTER_DESTROY_EVENT, instance, t); instance = null; instancePool = null; nInstances = 0; fireContainerEvent("unload", this); unloading = false; throw new ServletException (sm.getString("standardWrapper.destroyException", getName()), t); } finally { // restore the context ClassLoader Thread.currentThread().setContextClassLoader(oldCtxClassLoader); // Write captured output if (swallowOutput) { String log = SystemLogHandler.stopCapture(); if (log != null && log.length() > 0) { if (getServletContext() != null) { getServletContext().log(log); } else { out.println(log); } } } } // Deregister the destroyed instance instance = null; if (singleThreadModel && (instancePool != null)) { try { Thread.currentThread().setContextClassLoader(classLoader); while (!instancePool.isEmpty()) { if( System.getSecurityManager() != null) { SecurityUtil.doAsPrivilege("destroy", ((Servlet) instancePool.pop())); SecurityUtil.remove(instance); } else { ((Servlet) instancePool.pop()).destroy(); } } } catch (Throwable t) { instancePool = null; nInstances = 0; unloading = false; fireContainerEvent("unload", this); throw new ServletException (sm.getString("standardWrapper.destroyException", getName()), t); } finally { // restore the context ClassLoader Thread.currentThread().setContextClassLoader (oldCtxClassLoader); } instancePool = null; nInstances = 0; } singleThreadModel = false; unloading = false; fireContainerEvent("unload", this); } 0 0
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