springMVC源码分析--视图AbstractView和InternalResourceView（二）

清疚 2022-07-12 09:40 315阅读 0赞

上一篇博客[ springMVC源码分析--视图View（一）][springMVC_--_View]中我们介绍了简单介绍了View的结构实现及运行流程，接下来我们介绍一下View的实现类做的处理操作。

AbstractView实现了render方法，主要做的操作是将model中的参数和request中的参数全部都放到Request中，然后就转发Request就可以了。

@Override
    	public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
    		if (logger.isTraceEnabled()) {
    			logger.trace("Rendering view with name '" + this.beanName + "' with model " + model +
    				" and static attributes " + this.staticAttributes);
    		}
    		//将model和request中的参数全部放到mergedModel中
    		Map<String, Object> mergedModel = createMergedOutputModel(model, request, response);
    		//存放头部信息
    		prepareResponse(request, response);
    		//将mergedModel中的参数值放到request中
    		renderMergedOutputModel(mergedModel, getRequestToExpose(request), response);
    	}

createMergedOutputModel中的操作就是将所有的数据放到mergedModel中。

protected Map<String, Object> createMergedOutputModel(Map<String, ?> model, HttpServletRequest request,
    			HttpServletResponse response) {
    
    		@SuppressWarnings("unchecked")
    		Map<String, Object> pathVars = (this.exposePathVariables ?
    				(Map<String, Object>) request.getAttribute(View.PATH_VARIABLES) : null);
    
    		// Consolidate static and dynamic model attributes.
    		int size = this.staticAttributes.size();
    		size += (model != null ? model.size() : 0);
    		size += (pathVars != null ? pathVars.size() : 0);
    
    		Map<String, Object> mergedModel = new LinkedHashMap<String, Object>(size);
    		mergedModel.putAll(this.staticAttributes);
    		if (pathVars != null) {
    			mergedModel.putAll(pathVars);
    		}
    		if (model != null) {
    			mergedModel.putAll(model);
    		}
    
    		// Expose RequestContext?
    		if (this.requestContextAttribute != null) {
    			mergedModel.put(this.requestContextAttribute, createRequestContext(request, response, mergedModel));
    		}
    
    		return mergedModel;
    	}

prepareResponse中的操作就是在头部中添加信息。

protected void prepareResponse(HttpServletRequest request, HttpServletResponse response) {
    		if (generatesDownloadContent()) {
    			response.setHeader("Pragma", "private");
    			response.setHeader("Cache-Control", "private, must-revalidate");
    		}
    	}

renderMergedOutputModel是在子类中实现的，我们介绍一下我们经常使用的普通jsp源码使用的InternalResourceView

@Override
    	protected void renderMergedOutputModel(
    			Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
    
    		//把model中的所有数据放到request中
    		exposeModelAsRequestAttributes(model, request);
    
    		exposeHelpers(request);
    
    		//看看是否有跳转页面
    		String dispatcherPath = prepareForRendering(request, response);
    
    		// Obtain a RequestDispatcher for the target resource (typically a JSP).
    		RequestDispatcher rd = getRequestDispatcher(request, dispatcherPath);
    		if (rd == null) {
    			throw new ServletException("Could not get RequestDispatcher for [" + getUrl() +
    					"]: Check that the corresponding file exists within your web application archive!");
    		}
    
    		// If already included or response already committed, perform include, else forward.
    		if (useInclude(request, response)) {
    			response.setContentType(getContentType());
    			if (logger.isDebugEnabled()) {
    				logger.debug("Including resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
    			}
    			//加载页面
    			rd.include(request, response);
    		}
    
    		else {
    			// Note: The forwarded resource is supposed to determine the content type itself.
    			if (logger.isDebugEnabled()) {
    				logger.debug("Forwarding to resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
    			}
    			//转发操作
    			rd.forward(request, response);
    		}
    	}

以上代码就完成了springMVC的所有处理操作，springMVC最终的操作就是调用request及response完成请求操作了。

[springMVC_--_View]: http://blog.csdn.net/qq924862077/article/details/55666920