spring的源码分析(1) DispatcherServlet

//渲染jsp的流程
DispatcherServlet(HttpServlet).service(HttpServletRequest, HttpServletResponse)
DispatcherServlet(FrameworkServlet).doGet(HttpServletRequest, HttpServletResponse)
DispatcherServlet(FrameworkServlet).processRequest(HttpServletRequest, HttpServletResponse)
DispatcherServlet.doService(HttpServletRequest, HttpServletResponse)
DispatcherServlet.doDispatch(HttpServletRequest, HttpServletResponse)
AnnotationMethodHandlerAdapter.handle(HttpServletRequest, HttpServletResponse,HandlerExecutionChain handler)  //mappedHandler.getHandler()
AnnotationMethodHandlerAdapter.invokeHandlerMethod(HttpServletRequest, HttpServletResponse, HandlerExecutionChain handler)

Method.invoke(Object, Object...)
DelegatingMethodAccessorImpl.invoke(Object, Object[])
NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) [native method]
HelloWorldController.hello(Model)

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
    protected final void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }
    protected final void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doService(request, response);
    }
    protected abstract void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
        try {doDispatch(request, response);}
    }
}

public class DispatcherServlet extends FrameworkServlet {

    //doDispatch()是DispatcherServlet类 调度的核心
    protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
        HandlerExecutionChain mappedHandler = null;
        try {
            ModelAndView mv   = null;
            Exception exception = null;
            try {
                //核心1：查找映射处理器HandlerExecutionChain
                mappedHandler = getHandler(request); // Determine handler for the current request.
                if (mappedHandler == null || mappedHandler.getHandler() == null) {
                    noHandlerFound(request, response);
                    return;
                }


                //核心2：查找处理适配器HandlerAdapter
                // Determine handler adapter for the current request.
                HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());

                if (!mappedHandler.applyPreHandle(request, response)) {
                    return;
                }

                //调用功能处理器相应的方法,如[public java.util.Map com.demo.springmvc.HelloWorldController.json(org.springframework.ui.Model)]
                // Actually invoke the handler.
                mv = ha.handle(request, response, mappedHandler.getHandler());

                applyDefaultViewName(request, mv);
                mappedHandler.applyPostHandle(request, response, mv);
            }
            catch (Exception ex) {
                exception = ex;
            }

            //处理分发结果并渲染视图
            processDispatchResult(request, response, mappedHandler, mv, exception);
        }
        catch (Exception ex) {
            triggerAfterCompletion(request, response, mappedHandler, ex);
        }
        catch (Error err) {
            triggerAfterCompletionWithError(request, response, mappedHandler, err);
        }
        finally {
        }
    }

    private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
        HandlerExecutionChain mappedHandler, ModelAndView mv, Exception exception) throws Exception {
        boolean errorView = false;

        if (exception != null) { //异常处理，
            if (exception instanceof ModelAndViewDefiningException) {
                logger.debug("ModelAndViewDefiningException encountered", exception);
                mv = ((ModelAndViewDefiningException) exception).getModelAndView();
            }
            else {
                Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
                mv = processHandlerException(request, response, handler, exception);
            }
        }

        // Did the handler return a view to render?
        if (mv != null && !mv.wasCleared()) {
            render(mv, request, response);
        }
        if (mappedHandler != null) {
            mappedHandler.triggerAfterCompletion(request, response, null);
        }
    }
}

package org.springframework.web.servlet;
public class HandlerExecutionChain {
    private final Object handler;
    //HandlerExecutionChain with handler [public java.util.Map com.demo.springmvc.HelloWorldController.json(org.springframework.ui.Model)] and 1 interceptor

    private HandlerInterceptor[] interceptors;
    //[org.springframework.web.servlet.handler.ConversionServiceExposingInterceptor@1663921]

    private List<HandlerInterceptor> interceptorList;
    public Object getHandler() {
        return this.handler;
    }
    public String toString();
}
HandlerExecutionChain
Handler execution chain, consisting of handler object and any handler interceptors.
Returned by HandlerMapping's HandlerMapping.getHandler(javax.servlet.http.HttpServletRequest) method.

Method Summary
void addInterceptor(HandlerInterceptor interceptor)
void addInterceptors(HandlerInterceptor... interceptors)
java.lang.Object getHandler()                 //Return the handler object to execute.
HandlerInterceptor[] getInterceptors()   //Return the array of interceptors to apply (in the given order).
java.lang.String toString()                       //Delegates to the handler's toString().

package org.springframework.web.servlet;
public interface HandlerAdapter {
    boolean supports(Object handler);
    ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;
}

All Known Implementing Classes:
AbstractHandlerMethodAdapter,
AnnotationMethodHandlerAdapter,
HttpRequestHandlerAdapter,
RequestMappingHandlerAdapter,
SimpleControllerHandlerAdapter,
SimpleServletHandlerAdapter

public abstract class AbstractHandlerMethodAdapter extends WebContentGenerator implements HandlerAdapter, Ordered {
    //handleInternal是抽象方法
    protected abstract ModelAndView handleInternal(HttpServletRequest request,HttpServletResponse response, HandlerMethod handlerMethod) throws Exception;

    public final boolean supports(Object handler) {
        return (handler instanceof HandlerMethod && supportsInternal((HandlerMethod) handler));
    }
    public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return handleInternal(request, response, (HandlerMethod) handler);
    }
}

public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter implements BeanFactoryAware, InitializingBean {
    private ModelAndView invokeHandleMethod(HttpServletRequest request,HttpServletResponse response, HandlerMethod handlerMethod) throws Exception
    {
        requestMappingMethod.invokeAndHandle(webRequest, mavContainer);
        return getModelAndView(mavContainer, modelFactory, webRequest);
    }
}

public class AnnotationMethodHandlerAdapter extends WebContentGenerator implements HandlerAdapter, Ordered, BeanFactoryAware {
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, HandlerExecutionChain handler) throws Exception {
        return invokeHandlerMethod(request, response, handler);
    }
    protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, HandlerExecutionChain handler)  throws Exception {
        ServletHandlerMethodResolver methodResolver = getMethodResolver(handler);
        Method handlerMethod = methodResolver.resolveHandlerMethod(request);
        ServletHandlerMethodInvoker methodInvoker = new ServletHandlerMethodInvoker(methodResolver);
        ServletWebRequest webRequest = new ServletWebRequest(request, response);
        ExtendedModelMap implicitModel = new BindingAwareModelMap();

        Object result = methodInvoker.invokeHandlerMethod(handlerMethod, handler, webRequest, implicitModel); //ModelAndView
        ModelAndView mv =
                methodInvoker.getModelAndView(handlerMethod, handler.getClass(), result, implicitModel, webRequest);
        methodInvoker.updateModelAttributes(handler, (mv != null ? mv.getModel() : null), implicitModel, webRequest);
        return mv;
    }
}