关于commons-fileupload组件上传文件中文名乱码问题

　　java web开发，经常使用到的文件上传功能，经常使用的commons-fileupload和commons-io两个jar包。关于如何使用这两个jar来完成文件上传的功能，这里不作详解。使用commons-fileupload来上传文件，有两种方式能够是实现。

1. 传统API

 1 <%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" language="java"%>
 2 <%@page import="java.io.File"%>
 3 <%@page import="java.util.List"%>
 4 <%@page import="org.apache.commons.fileupload.*"%>
 5 <%@page import="org.apache.commons.fileupload.disk.DiskFileItemFactory"%>
 6 <%@page import="org.apache.commons.fileupload.servlet.ServletFileUpload"%>
 7 
 8 <%
 9     request.setCharacterEncoding("UTF-8");
10     // file less than 10kb will be store in memory, otherwise in file system.
11     final int threshold = 10240;
12     final File tmpDir = new File(getServletContext().getRealPath("/") + "fileupload" + File.separator + "tmp");
13     final int maxRequestSize = 1024 * 1024 * 4;    // 4MB
14 
15     // Check that we have a file upload request
16     if(ServletFileUpload.isMultipartContent(request))
17     {
18         // Create a factory for disk-based file items.
19         FileItemFactory factory = new DiskFileItemFactory(threshold, tmpDir);
20         
21         // Create a new file upload handler
22         ServletFileUpload upload = new ServletFileUpload(factory);
23 
24         // Set overall request size constraint.
25         upload.setSizeMax(maxRequestSize);
26 
27         List<FileItem> items = upload.parseRequest(request);    // FileUploadException 
28         for(FileItem item : items)
29         {
30             if(item.isFormField())    //regular form field
31             {
32                 String name = item.getFieldName();
33                 String value = item.getString();
34 %>
35                 <h1><%=name%> --> <%=value%></h1>
36 <%
37             }
38             else
39             {    //file upload
40                 String fieldName = item.getFieldName();
41                 String fileName = item.getName();
42                 File uploadedFile = new File(getServletContext().getRealPath("/") +
43                             "fileupload" + File.separator + fieldName + "_" + fileName);
44                 item.write(uploadedFile);
45 %>
46                 <h1>upload file <%=uploadedFile.getName()%> done!</h1>
47 <%
48             }
49         }
50     }
51 %>

2. Stream API

 1 <%@page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" language="java"%>
 2 <%@page import="java.io.*"%>
 3 <%@page import="java.util.List"%>
 4 <%@page import="org.apache.commons.fileupload.*"%>
 5 <%@page import="org.apache.commons.fileupload.util.Streams"%>
 6 <%@page import="org.apache.commons.fileupload.servlet.ServletFileUpload"%>
 7 
 8 <%
 9     request.setCharacterEncoding("UTF-8");
10 
11     // Check that we have a file upload request
12     if(ServletFileUpload.isMultipartContent(request))
13     {    
14         // Create a new file upload handler
15         ServletFileUpload upload = new ServletFileUpload();
16         
17         // Parse the request
18         FileItemIterator iter = upload.getItemIterator(request);
19 
20         while(iter.hasNext())
21         {
22             FileItemStream item = iter.next();
23             String fieldName = item.getFieldName();
24             InputStream is = item.openStream();
25 
26             if(item.isFormField())    //regular form field
27             {
28 %>
29                 <!-- read a FileItemStream's content into a string. -->
30                 <h1><%=fieldName%> --> <%=Streams.asString(is)%></h1>
31 <%
32             }
33             else
34             {    //file upload
35                 String fileName = item.getName();
36                 File uploadedFile = new File(getServletContext().getRealPath("/") +
37                             "fileupload" + File.separator + fieldName + "_" + fileName);
38                 OutputStream os = new FileOutputStream(uploadedFile);
39                 // write file to disk and close outputstream.
40                 Streams.copy(is, os, true);
41 %>
42                 <h1>upload file <%=uploadedFile.getName()%> done!</h1>
43 <%
44             }
45         }
46     }
47 %>

　　Streaming API上传速度相对较快。由于它是利用内存保存上传的文件，节省了传统API将文件写入临时文件带来的开销。天然，更倾向于选用Stream API。

　　前端实现文件上传的“手段”，目前接触过的有UEditor的上传组件、jQuery的ajaxfileupload以及AngularJs的集成上传组件。发送的也都是正常的上传表单数据，而当使用Stream API，获取文件名时，“String fileName = item.getName()”，当文件名为中文名时，会出现乱码现象。

　　网上搜寻的关于设置request编码的法子都无论用，尝试了屡次后，找到了解决办法，重点在于上面代码中的ServletFileUpload upload，添加upload.setHeaderEncoding("UTF-8");便可解决中文文件名的乱码问题了。