Struts2默认对request进行了编码设置

直接贴Struts2的源码

按照执行流程

1.FilterDispacher类中：

/**
      * Wrap and return the given request, if needed, so as to to transparently
      * handle multipart data as a wrapped class around the given request.
      *
      * @param request Our ServletRequest object
      * @param response Our ServerResponse object
      * @return Wrapped HttpServletRequest object
      * @throws ServletException on any error
      */
     protected HttpServletRequest prepareDispatcherAndWrapRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException {
     	/*
     	 * 不明白，dispatcher实例是何时给本地线程的
     	 * 
     	 * 经debug后，发现最初的dispatcher实例是在FilterDispatcher中的init方法已经初始化了
     	 */
         Dispatcher du = Dispatcher.getInstance();//每次的请求会是null：意味每次的本地线程都不同，因此会变成null
 
         // Prepare and wrap the request if the cleanup filter hasn't already, cleanup filter should be
         // configured first before struts2 dispatcher filter, hence when its cleanup filter's turn,
         // static instance of Dispatcher should be null.
         if (du == null) {
         	
             Dispatcher.setInstance(dispatcher);
 
             
             // prepare the request no matter what - this ensures that the proper character encoding
             // is used before invoking the mapper (see WW-9127)
             /*
              * 对于该prepare方法：struts2默认设置了request的setCharacterEncoding()方法，姑且先
              * 不讨论设置成utf-8或者gbk会对获取客户端的参数有何种影响，我们首先肯定的是struts2对request
              * 进行了编码设置，因此我会觉得在struts2作为web框架中增加编码设置变得非常多余
              */
             dispatcher.prepare(request, response);
         } else {
             dispatcher = du;
         }
         
         try {
             // Wrap request first, just in case it is multipart/form-data
             // parameters might not be accessible through before encoding (ww-1278)
             request = dispatcher.wrapRequest(request, getServletContext());
         } catch (IOException e) {
             String message = "Could not wrap servlet request with MultipartRequestWrapper!";
             LOG.error(message, e);
             throw new ServletException(message, e);
         }
 
         return request;
     }

2.Dispatcher类中：

 /**
      * Prepare a request, including setting the encoding and locale.
      *
      * @param request The request
      * @param response The response
      */
     public void prepare(HttpServletRequest request, HttpServletResponse response) {
         String encoding = null;
         //默认编码
         if (defaultEncoding != null) {
             encoding = defaultEncoding;
         }
 
         Locale locale = null;
         if (defaultLocale != null) {
             locale = LocalizedTextUtil.localeFromString(defaultLocale, request.getLocale());
         }
 
         if (encoding != null) {
             try {
             	//设置默认编码
                 request.setCharacterEncoding(encoding);
             } catch (Exception e) {
                 LOG.error("Error setting character encoding to '" + encoding + "' - ignoring.", e);
             }
         }
 
         if (locale != null) {
             response.setLocale(locale);
         }
 
         if (paramsWorkaroundEnabled) {
             request.getParameter("foo"); // simply read any parameter (existing or not) to "prime" the request
         }
     }
 

3.Dispatcher类中：

 public HttpServletRequest wrapRequest(HttpServletRequest request, ServletContext servletContext) throws IOException {
         // don't wrap more than once
     	/*
     	 * 猜想疑惑：request的实例化使用sevlet容器进行初始化的，
     	 * 但是为何这边要出现if判断其属于那种request下的实例，StrutsRequestWrapper或者MultiPartRequestWrapper下
     	 * 那下面if如果要满足的话，前提必须进行了如下初始化
     	 * 	猜想：HttpSevrletRequest request=new StrutsRequestWrapper();
     	 * 那问题便出来了，如何进行request初始化，还是容器吗？
     	 * 每次请求都会初始化吗？他知道有StrutsRequestWrapper类吗？
     	 *  如果前面猜想不成立的话：那么if永远也进步下去
     	*/
         if (request instanceof StrutsRequestWrapper) {
             return request;
         }
         //由于contentype的不同会使用不同的解析方式对request中的信息进行解析，
         //故此进行判断
         String content_type = request.getContentType();
         if (content_type != null && content_type.indexOf("multipart/form-data") != -1) {
         	//主要涉及到Container和实现类ContainerImpl的设计思路，待日后研究
             MultiPartRequest multi = getContainer().getInstance(MultiPartRequest.class);
             //这里包含了上传文件的解析流程，仔细看还是可以看懂的，具体问题具体研究吧
             request = new MultiPartRequestWrapper(multi, request, getSaveDir(servletContext));
         } else {
         	//原来request在这里被struts2的request包裹类了。尼玛。
             request = new StrutsRequestWrapper(request);
         }
 
         return request;
     }

如何更改struts2对于request的默认编码设置：<constant name="struts.i18n.encoding" value="utf-8/gbk" /> ps：默认情况下是utf-8

(struts2核心包下的default.properties中设置了默认编码值)

参考资料：http://blog.csdn.net/elimago/article/details/3601579

总结：

1.struts2默认对request进行了编码设置

2.Container和ContainerImpl实现类的设计准则待研究

3.对于上传文件的解析深入request = new MultiPartRequestWrapper(multi, request, getSaveDir(servletContext));待研究