servlet文件上传实现进度条提示

package com.it.servlet; 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; import org.json.JSONException; import org.json.JSONObject; import com.it.listener.FileUploadListener; import com.it.util.SnowFlakeUtils; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.File; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import java.util.UUID; public class ProgressUploadServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); JSONObject json=new JSONObject(); //判断用户请求是否为multipart类型 if(ServletFileUpload.isMultipartContent(request)){ //创建磁盘工厂，设置内存大小和临时存储位置 DiskFileItemFactory factory=new DiskFileItemFactory(); //如果文件大小大于内存大小则存储在临时存储空间 //临时文件使用之后会自动删除 //如果不设置，默认的临时存储空间是:C:\Users\Administrator\AppData\Local\Temp File tempDirFile= new File("D:\\tempDir"); if(!tempDirFile.exists()){ tempDirFile.mkdir();//如果目录不存在就创建 } factory.setRepository(tempDirFile); //创建ServletFileUpload设置单个文件上传大小以及整个request域大小 ServletFileUpload upload=new ServletFileUpload(factory); //创建ProgressListener对象监听文件上传进度 upload.setProgressListener(new FileUploadListener(request)); //解析request域,list中存放了表单数据+文件 try { List<FileItem> list=upload.parseRequest(request); for (FileItem item:list){ if(item.isFormField()){ //如果是表单数据 if(item.getFieldName().equals("user_id")){ String user_id=item.getString("utf-8"); } }else { //如果是上传的文件 //解析出文件后缀名 String fileSuffxName=item.getName().substring(item.getName().lastIndexOf(".")); //用雪花算法生成一个名称+文件后缀形成一个新的名字 //最终将文件存储在D:\\upload\\目录中 File file=new File("D:\\upload\\"+ SnowFlakeUtils.nextId()+fileSuffxName); item.write(file); json.put("data","success"); } } } catch (FileUploadException e) { try { json.put("data","error"); } catch (JSONException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } e.printStackTrace(); } catch (Exception e){ e.printStackTrace(); try { json.put("data","error"); } catch (JSONException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } } //返回json字符串，告知前端上传时成功还是失败 response.getWriter().print(json.toString()); } }