今天我用commons-fileupload組件上傳文件，代碼是正確的，而且我把commons-fileupload-1.2.1.jar,commons-io-1.4.jar也導入到項目目項中，但總是出現這樣那樣的錯誤，讓我花了不少的時間,所以我把相關發出來,對有此類的問題的朋友有所幫助
如:
java.lang.RuntimeException: Unable to load bean org.apache.struts2.dispatcher.multipart.MultiPartRequest (jakarta) - [unknown location]
……………………
在網上查了很多資料，后來總結了一下，如果你是在struts2項目中用commons-fileupload組件的話，那就應
該把修改web.xml，把原來的
<filter-mapping>
<filter-name>struts</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
改為
<filter-mapping>
<filter-name>struts</filter-name>
<url-pattern>*.action</url-pattern>
</filter-mapping>
而上傳頁面調用時直接用文件名調用（如upload.jsp）。struts2只處理 *.action 的請求。
或者
<filter>
<filter-name>struts2</filter-name>
<filter-class>
org.apache.struts2.dispatcher.FilterDispatcher
</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
去掉也行
若是java.lang.NoClassDefFoundError: org/apache/commons/fileupload/FileUploadException錯誤
那就有可能是導包的問題，若用的是右擊項目，選擇屬性，然后導入相應的包，就有可能出顯此類的錯誤，解決方法是：把commons-fileupload-1.2.1.jar,commons-io-1.4.jar復制到到WEB-INF下的lib目錄中，雖然效果是一樣，但不會出錯了
附:
upload.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GB2312"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'upload.jsp' starting page</title>
</head>
<body>
<form action="upload" method="post" enctype="multipart/form-data">
用戶名：<input type="text" name="username"><br>
密碼：<input type="password" name="password"><br>
文件1:<input type="file" name="file1"><br>
文件2:<input type="file" name="file2"><br>
<input type="submit" value="提交"><br>
</form>
</body>
</html>
UploadServlet.java
package com.test.servlet1;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
DiskFileItemFactory factory = new DiskFileItemFactory();
String path = request.getRealPath("/upload");
// 設置傳輪輸文件的大小，當小于1024時，把文件存在茲盤上
factory.setRepository(new File(path));
factory.setSizeThreshold(1024 * 1024);
ServletFileUpload upload = new ServletFileUpload(factory);
try {
List<FileItem> list = upload.parseRequest(request);
for(FileItem item : list){
if(item.isFormField()){
String name = item.getFieldName();
String value = item.getString("GB2312");
request.setAttribute(name, value);
}else{
String name = item.getFieldName();
String value = item.getName();
int start = value.lastIndexOf("\\");
String fileName = value.substring(start+1);
request.setAttribute(name, fileName);
//item.write(new File(path,fileName));
OutputStream os = new FileOutputStream(new File(path,fileName));
InputStream is = item.getInputStream();
// 將文件is寫到os里
byte[] buffer = new byte[400];
int lenght = 0 ;
while((lenght = is.read(buffer ))>0){
os.write(buffer,0,lenght);
}
os.close();
is.close();
}
}
} catch (FileUploadException e) {
// TODO Auto-generated catch block
System.out.println("文件上傳出錯"+e.getMessage());
e.printStackTrace();
}
request.getRequestDispatcher("upload/result.jsp").forward(request, response);
}
}
result.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GB2312"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'result.jsp' starting page</title>
</head>
<body>
用戶名:${requestScope.username }
密碼:${requestScope.password }
文件1:${requestScope.file1 }
文件2:${requestScope.file2 }
</body>
</html>