使用commons-fileupload多文件上传例子

准备: commons-fileupload-1.2.1.jar和commons-io-1.4.jar

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//System.out.println(request.getParameter("test"));
		request.setCharacterEncoding("utf-8");// 设置字符编码为UTF-8, 统一编码，处理出现乱码问题	
		
		
		//response.setContentType("text/html;charset=utf-8");
		//response.setCharacterEncoding("utf-8");
		boolean isMultipart = ServletFileUpload.isMultipartContent(request);//检查是否是一个文件上传请求
		if(isMultipart){
//			 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload 
			DiskFileItemFactory factory = new DiskFileItemFactory();	
			
//			 设置上传文件时用于临时存放文件的内存大小,这里是2K.多于的部分将临时存在硬盘
			factory.setSizeThreshold(1024*2);
//			 设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录
			factory.setRepository(new File("c:\\file"));//临时文件
			
//			以上两项可通过DiskFileItemFactory构参来创建
//			DiskFileItemFactory factory = new DiskFileItemFactory(yourMaxMemorySize, yourTempDirectory);
			

//			 用上面的工厂实例化上传组件，
			ServletFileUpload upload = new ServletFileUpload(factory);
			//upload.setFileItemFactory(factory);
//			如果ServletFileUpload实例中不设置上面的Factory则报java.lang.NullPointerException: No FileItemFactory has been set.

//			 设置最大上传大小 10M
			upload.setSizeMax(1024*1024*10);			
			String name = "";
			try {
				List  items = upload.parseRequest(request); // 得到所有FileItem 			
				Iterator iter = items.iterator();
//				 循环处理所有文件
				while (iter.hasNext()) {
				    FileItem item = (FileItem) iter.next();
				    if (!item.isFormField()) {//  判断是否是表单元素(<input type="text" />单选，多选等)
				    	name = item.getName();// 得到文件的名称
				    	if(name==null || "".equals(name.trim())){
//				    		 未选择上传文件
				    		continue;
				    	}
				        
				        long size = item.getSize();//文件长度
				        File file = new File("c:\\file\\"+name);
						if(file.exists()){
							file.delete();
						}
				        item.write(file);
				    }else{
				    	//<input name="test" size="40" type="text">
				    	//String value = item.getString();//表单元素的值,用在非文件上传域中 
				    	//String fieldName = item.getFieldName();////表单元素的名称，用在非文件上传域中 **test**
				    	System.out.println(item.getFieldName()+"  "+new String(item.getString().getBytes("ISO-8859-1"),"utf-8"));//处理中文问题
				    }
				}
				
			} catch (FileUploadException e) {
//				 处理文件尺寸过大异常
				e.printStackTrace();
			} catch (Exception e) {
//				 处理文件写入时的异常
				System.out.println("Write Error: "+name);
				e.printStackTrace();
			}
		}
		request.getRequestDispatcher("/jsp/su.jsp").forward(request, response);
	}

使用流读取：

//API中提供的按流的形式读取
	void uploadByStream(HttpServletRequest request) throws FileUploadException, IOException{
		
		boolean isMultipart = ServletFileUpload.isMultipartContent(request);
		String name = "";
		if (isMultipart) {
			ServletFileUpload upload = new ServletFileUpload();
			upload.setSizeMax(1024*1024*10);
			FileItemIterator fileItemIterator = upload.getItemIterator(request);
			while(fileItemIterator.hasNext()){
				FileItemStream stream = fileItemIterator.next();
				if(!stream.isFormField()){
					name = stream.getName();// 得到文件的名称
			    	if(name==null || "".equals(name.trim())){
			    		continue;
			    	}
			    	File file = new File("c:\\file\\"+name);
					if(file.exists()){
						file.delete();
					}
					InputStream is = stream.openStream();					
					ByteArrayOutputStream bStream = new ByteArrayOutputStream();
					long size = Streams.copy(is,bStream,true);
					OutputStream op = new FileOutputStream(file);
					bStream.writeTo(op);
					
				}else{
					InputStream is = stream.openStream();
					InputStreamReader isr = new InputStreamReader(is,"utf-8");
					BufferedReader br = new BufferedReader(isr);
					char b[] = new char[1024];
					int len = 0;
					StringBuffer sb = new StringBuffer();
					String line = null;
					while((line=br.readLine())!=null){
						sb.append(line);
					}
//					while((len=isr.read(b))!=-1){
//						System.out.println("len= "+len);						
//						sb.append(new String(b,0,len));
//					}
					System.out.println(stream.getFieldName()+"  "+sb.toString());
				}
			}
		}
	}

HTML：

<FORM action="/servlet/FileUpServlet" method="post" enctype="multipart/form-data">
       <table border="1" width="450" cellpadding="4" cellspacing="2" bordercolor="#9BD7FF">

          <tr><td width="100%" colspan="2">

                          文件1：<input name="x" size="40" type="file">

          </td></tr>

          <tr><td width="100%" colspan="2">

                          文件2：<input name="y" size="40" type="file">

          </td></tr>

          <tr><td width="100%" colspan="2">

                          文件3：<input name="z" size="40" type="file">

          </td></tr>
           <tr><td width="100%" colspan="2">

                          文件4：<input name="a" size="40" type="file">

          </td></tr>
           <tr><td width="100%" colspan="2">

                          文件5：<input name="b" size="40" type="file">

          </td></tr>
          
          <tr><td width="100%" colspan="2">

                          文件6：<input name="test" size="40" type="text">

          </td></tr>

          </table>

          <br/><br/>

          <table>

          <tr><td align="center"><input name="upload" type="submit" value="开始上传"/></td></tr>

         </table>

     
      </FORM>