webwork的多文件上传

        前天在做分类图标管理的时候，需要同时上传两个图标。但在处理的时候老报错，在google上找到有用的信息：

File upload support has been rebuilt to allow for multiple files with the same HTTP parameter name. Besides "cos" and "pell" support, "jakarta" support has been added, utilizing the Commons-FileUpload library. Only "jakarta" supports multiple files with the same HTTP parameter name. In future versions "jakarta" may become the default upload library, replacing "pell"，作者还说将webwork.properties的webwork.multipart.parser设为com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest就可以了。

         再看一下我们项目的webwork.properties，真是晕死，人家webwork已经调jakata设为默认上传组件了，我们的webwork.properties竟然还硬要设为pell，这不是蓄意谋杀么？

         当时图个爽快，按照这样仁兄的设置，果然成功了。今天早上回来看了一下webwork的代码，发现有点不对路。Webwork里的com.opensymphony.webwork.dispatcher.multipart.MultiPartRequestWrapper里面有几行代码，是判断使用那个上传组件的。以下是摘抄：

if (request instanceof MultiPartRequest) {

            multi = (MultiPartRequest) request;

  } else {

      String parser = Configuration.getString(WebWorkConstants.WEBWORK_MULTIPART_PARSER);



            // If it's not set, use Jakarta

            if (parser.equals("")) {

                log.warn("Property webwork.multipart.parser not set." +

                        " Using com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest");

                parser = "com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest";

            }

            // legacy support for old style property values

            else if (parser.equals("pell")) {

                parser = "com.opensymphony.webwork.dispatcher.multipart.PellMultiPartRequest";

            } else if (parser.equals("cos")) {

                parser = "com.opensymphony.webwork.dispatcher.multipart.CosMultiPartRequest";

            } else if (parser.equals("jakarta")) {

                parser = "com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest";

            }

为什么将webwork.multipart.parser设为com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest也是可以的？理论上应该设为jakata才对，除非在if子句中已经执行了，跳过了下面的else子句。