层层递进Struts1（五）之处理流程

层层递进Struts1（五）之处理流程2013-12-07 csdn 李达这篇博客我们深入Struts框架执行部分源码，从ActionServlet的process函数开始，看一下其内在的执行过程。

流程图

以下流程图展示的是ActionServlet和RequestProcessor两个类用到的函数，如RequestProcessor调用的其它类的函数不再说明。

函数说明

我们选择几个重要的函数说明，其它函数则简单说明一下即可。

ActionServlet

process

/** 
 * <p>Perform the standard request processing for this request, and create 
 * the corresponding response.</p> 
 * 
 * @param request The servlet request we are processing 
 * @param response The servlet response we are creating 
 * 
 * @exception IOException if an input/output error occurs 
 * @exception ServletException if a servlet exception is thrown 
 */protected void process（HttpServletRequest request, HttpServletResponse response）
throws IOException, ServletException {
ModuleUtils.getInstance（）.selectModule（request, getServletContext（））;
ModuleConfig config = getModuleConfig（request）;
RequestProcessor processor = getProcessorForModule（config）;
if （processor == null） {
 processor = getRequestProcessor（config）;
}
processor.process（request, response）;
}
}

在调试时首先进入这个函数（Tomcat启动完毕，产生请求后），这个函数的作用是获取加载阶段产生的 Module对象，产生struts逻辑处理的主要对象RequestProcessor。

RequestProcessor

process

/** 
* <p>Process an <code>HttpServletRequest</code> and create the 
* corresponding <code>HttpServletResponse</code> or dispatch 
* to another resource.</p> 
* 
* @param request The servlet request we are processing 
* @param response The servlet response we are creating 
* 
* @exception IOException if an input/output error occurs 
* @exception ServletException if a processing exception occurs 
*/ public void process（HttpServletRequest request,
 HttpServletResponse response）
 throws IOException, ServletException {
 // Wrap multipart requests with a special wrapper
 request = processMultipart（request）;
 // Identify the path component we will use to select a mapping
 String path = processPath（request, response）;
 if （path == null） {
 return;
 }
 if （log.isDebugEnabled（）） {
 log.debug（"Processing a "" + request.getMethod（） +
 "" for path "" + path + """）;
 }
 // Select a Locale for the current user if requested processLocale（request, response）;
 // Set the content type and no-caching headers if requested
 processContent（request, response）;
 processNoCache（request, response）;
 // General purpose preprocessing hook
 if （！processPreprocess（request, response）） {
 return;
 }
 this.processCachedMessages（request, response）;
 // Identify the mapping for this request
 ActionMapping mapping = processMapping（request, response, path）;
 if （mapping == null） {
 return;
 }
 // Check for any role required to perform this action
 if （！processRoles（request, response, mapping）） {
 return;
 }
 // Process any ActionForm bean related to this request
 ActionForm form = processActionForm（request, response, mapping）;
 processPopulate（request, response, form, mapping）;
 // Validate any fields of the ActionForm bean, if applicable
 try {
 if （！processValidate（request, response, form, mapping）） {
 return;
 }
 } catch （InvalidCancelException e） {
 ActionForward forward = processException（request, response, e, form, mapping）;
 processForwardConfig（request, response, forward）;
 return;
 } catch （IOException e） {
 throw e;
 } catch （ServletException e） {
 throw e;
 }
 // Process a forward or include specified by this mapping
 if （！processForward（request, response, mapping）） {
 return;
 }
 if （！processInclude（request, response, mapping）） {
 return;
 }
 // Create or acquire the Action instance to process this request
 Action action = processActionCreate（request, response, mapping）;
 if （action == null） {
 return;
 }
 // Call the Action instance itself
 ActionForward forward =
 processActionPerform（request, response,
action, form, mapping）;
 // Process the returned ActionForward instance
 processForwardConfig（request, response, forward）;
 }