standardwrapper.java

业界著名的tomcat服务器的最新6.0的源代码。

    }


    /**
     * Return the associated servlet instance.
     */
    public Servlet getServlet() {
        return instance;
    }
    
    
    /**
     * Allocate an initialized instance of this Servlet that is ready to have
     * its <code>service()</code> method called.  If the servlet class does
     * not implement <code>SingleThreadModel</code>, the (only) initialized
     * instance may be returned immediately.  If the servlet class implements
     * <code>SingleThreadModel</code>, the Wrapper implementation must ensure
     * that this instance is not allocated again until it is deallocated by a
     * call to <code>deallocate()</code>.
     *
     * @exception ServletException if the servlet init() method threw
     *  an exception
     * @exception ServletException if a loading error occurs
     */
    public Servlet allocate() throws ServletException {

        // If we are currently unloading this servlet, throw an exception
        if (unloading)
            throw new ServletException
              (sm.getString("standardWrapper.unloading", getName()));

        // If not SingleThreadedModel, return the same instance every time
        if (!singleThreadModel) {

            // Load and initialize our instance if necessary
            if (instance == null) {
                synchronized (this) {
                    if (instance == null) {
                        try {
                            if (log.isDebugEnabled())
                                log.debug("Allocating non-STM instance");

                            instance = loadServlet();
                        } catch (ServletException e) {
                            throw e;
                        } catch (Throwable e) {
                            throw new ServletException
                                (sm.getString("standardWrapper.allocate"), e);
                        }
                    }
                }
            }

            if (!singleThreadModel) {
                if (log.isTraceEnabled())
                    log.trace("  Returning non-STM instance");
                countAllocated++;
                return (instance);
            }

        }

        synchronized (instancePool) {

            while (countAllocated >= nInstances) {
                // Allocate a new instance if possible, or else wait
                if (nInstances < maxInstances) {
                    try {
                        instancePool.push(loadServlet());
                        nInstances++;
                    } catch (ServletException e) {
                        throw e;
                    } catch (Throwable e) {
                        throw new ServletException
                            (sm.getString("standardWrapper.allocate"), e);
                    }
                } else {
                    try {
                        instancePool.wait();
                    } catch (InterruptedException e) {
                        ;
                    }
                }
            }
            if (log.isTraceEnabled())
                log.trace("  Returning allocated STM instance");
            countAllocated++;
            return (Servlet) instancePool.pop();

        }

    }


    /**
     * Return this previously allocated servlet to the pool of available
     * instances.  If this servlet class does not implement SingleThreadModel,
     * no action is actually required.
     *
     * @param servlet The servlet to be returned
     *
     * @exception ServletException if a deallocation error occurs
     */
    public void deallocate(Servlet servlet) throws ServletException {

        // If not SingleThreadModel, no action is required
        if (!singleThreadModel) {
            countAllocated--;
            return;
        }

        // Unlock and free this instance
        synchronized (instancePool) {
            countAllocated--;
            instancePool.push(servlet);
            instancePool.notify();
        }

    }


    /**
     * Return the value for the specified initialization parameter name,
     * if any; otherwise return <code>null</code>.
     *
     * @param name Name of the requested initialization parameter
     */
    public String findInitParameter(String name) {

        synchronized (parameters) {
            return ((String) parameters.get(name));
        }

    }


    /**
     * Return the names of all defined initialization parameters for this
     * servlet.
     */
    public String[] findInitParameters() {

        synchronized (parameters) {
            String results[] = new String[parameters.size()];
            return ((String[]) parameters.keySet().toArray(results));
        }

    }


    /**
     * Return the mappings associated with this wrapper.
     */
    public String[] findMappings() {

        synchronized (mappings) {
            return (String[]) mappings.toArray(new String[mappings.size()]);
        }

    }


    /**
     * Return the security role link for the specified security role
     * reference name, if any; otherwise return <code>null</code>.
     *
     * @param name Security role reference used within this servlet
     */
    public String findSecurityReference(String name) {

        synchronized (references) {
            return ((String) references.get(name));
        }

    }


    /**
     * Return the set of security role reference names associated with
     * this servlet, if any; otherwise return a zero-length array.
     */
    public String[] findSecurityReferences() {

        synchronized (references) {
            String results[] = new String[references.size()];
            return ((String[]) references.keySet().toArray(results));
        }

    }


    /**
     * FIXME: Fooling introspection ...
     */
    public Wrapper findMappingObject() {
        return (Wrapper) getMappingObject();
    }


    /**
     * 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.
     * <p>
     * <b>IMPLEMENTATION NOTE</b>:  Servlets whose classnames begin with
     * <code>org.apache.catalina.</code> (so-called "container" servlets)
     * are loaded by the same classloader that loaded this class, rather than
     * the classloader for the current web application.
     * This gives such classes access to Catalina internals, which are
     * prevented for classes loaded for web applications.
     *
     * @exception ServletException if the servlet init() method threw
     *  an exception
     * @exception ServletException if some other loading problem occurs
     */
    public synchronized void load() throws ServletException {
        instance = loadServlet();
    }


    /**
     * 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 (SecurityUtil.isPackageProtectionEnabled()){
                    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();
                // Annotation processing
                if (!((Context) getParent()).getIgnoreAnnotations()) {
                    if (getParent() instanceof StandardContext) {
                       ((StandardContext)getParent()).getAnnotationProcessor().processAnnotations(servlet);
                       ((StandardContext)getParent()).getAnnotationProcessor().postConstruct(servlet);
                    }
                }
            } catch (ClassCastException e) {
                unavailable(null);
                // Restore the context ClassLoader
                throw new ServletException
                    (sm.getString("standardWrapper.notServlet", actualClass), e);
            } catch (Throwable e) {
                unavailable(null);
              
                // Added extra log statement for Bugzilla 36630:
                // http://issues.apache.org/bugzilla/show_bug.cgi?id=36630
                if(log.isDebugEnabled()) {
                    log.debug(sm.getString("standardWrapper.instantiate", actualClass), e);
                }

                // 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);