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spring mvc 的问题0

spring MVC 里的自定义controller

新的一个方法里给一个ModelAndView里放一个对象
这个方法然后返回一个String

我的问题是是，那个返回的页面是html它是怎么解析一个java对象的？

spring mvc

2013年4月08日 21:42

issu
0
0 0 5

采纳的答案

举个JstlView的例子（即如jsp）

JstlView继承了InternalResourceView：

/**
* Render the internal resource given the specified model.
* This includes setting the model as request attributes.
*/
@Override
protected void renderMergedOutputModel(
Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {

// Determine which request handle to expose to the RequestDispatcher.
HttpServletRequest requestToExpose = getRequestToExpose(request);

// Expose the model object as request attributes.
exposeModelAsRequestAttributes(model, requestToExpose);

// Expose helpers as request attributes, if any.
exposeHelpers(requestToExpose);

// Determine the path for the request dispatcher.
String dispatcherPath = prepareForRendering(requestToExpose, response);

// Obtain a RequestDispatcher for the target resource (typically a JSP).
RequestDispatcher rd = getRequestDispatcher(requestToExpose, 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(requestToExpose, response)) {
response.setContentType(getContentType());
if (logger.isDebugEnabled()) {
logger.debug("Including resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
}
rd.include(requestToExpose, response);
}

else {
// Note: The forwarded resource is supposed to determine the content type itself.
exposeForwardRequestAttributes(requestToExpose);
if (logger.isDebugEnabled()) {
logger.debug("Forwarding to resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
}
rd.forward(requestToExpose, response);
}
}

红色部分是把模型数据暴露给view，其具体实现在AbstractView的

/**
* Expose the model objects in the given map as request attributes.
* Names will be taken from the model Map.
* This method is suitable for all resources reachable by {@link javax.servlet.RequestDispatcher}.
* @param model Map of model objects to expose
* @param request current HTTP request
*/
protected void exposeModelAsRequestAttributes(Map<String, Object> model, HttpServletRequest request) throws Exception {
for (Map.Entry<String, Object> entry : model.entrySet()) {
String modelName = entry.getKey();
Object modelValue = entry.getValue();
if (modelValue != null) {
request.setAttribute(modelName, modelValue);
if (logger.isDebugEnabled()) {
logger.debug("Added model object '" + modelName + "' of type [" + modelValue.getClass().getName() +
"] to request in view with name '" + getBeanName() + "'");
}
}
else {
request.removeAttribute(modelName);
if (logger.isDebugEnabled()) {
logger.debug("Removed model object '" + modelName +
"' from request in view with name '" + getBeanName() + "'");
}
}
}
}
可以看到其实它把数据放到request中了

2013年4月09日 08:46

jinnianshilongnian
7280
2 3 591

1条评论

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看错了 html？其实也是个文件发送出去的时候替换里面的内容就行了服务器和浏览器交互的时候其实就是服务器把这个文件发送给浏览器读文件的时候替换一下里面内容不是很简单吗？

2013年4月08日 22:46

120183228
33
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添加评论

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ModelAndView view = new ModelAndView();
view.setView(new InternalResourceView("/error.jsp"));
view.addObject("REQUEST_ID", MDC.get(LoggingProcessFilter.REQUEST_ID));
view.addObject("EXCEPTION", "<pre>"+s.getString()+"</pre>");

在页面中使用${"REQUEST_ID"}就能输出

如果你要说原理那么就是jsp在服务器时其实也是一段字符串一行行解析看看有没jsp标签等一大堆标签然后进行处理 ModelAndView的这个标签也是现在处理的替换一下就行了理解jsp的本质你就明白了

2013年4月08日 22:45

120183228
33
0 0 4