使用 Commons-fileupload 上传文件

DiskFileItemFactory factory = new DiskFileItemFactory(); 
// 实例化硬盘文件工厂
factory.setSizeThreshold(8192);// 存放临时文件的内存大小
String tempPath = request.getRealPath("/") + "/images/temp"; 
if(!new File(tempPath).isDirectory()) 
   new File(tempPath).mkdirs(); 
factory.setRepository(new File(tempPath)); 

// 设置上传路径
uploadPath = request.getRealPath("/") + "/web/report/images/"; 
if(!new File(uploadPath).isDirectory()) 
   new File(uploadPath).mkdirs(); 
               
// 初始化上传组件，循环 form 中的所有 input 类型为 file 的 field，上传文件
ServletFileUpload upload = new ServletFileUpload(factory); 
List<FileItem> items = upload.parseRequest(request);        
Iterator<FileItem> itr = items.iterator(); 
while (itr.hasNext()) {// 依次处理每个 form field 
   FileItem item = (FileItem) itr.next(); 
   File savedFile = new File(uploadPath, "imageFileName.jpg"); 
   item.write(savedFile); 
} 

转自  http://www.oschina.net/code/snippet_12_3272