ajax实现带进度条的文件上传

来源：互联网发布：移动数据打开要收费吗编辑：程序博客网时间：2024/04/29 22:18

jsp部分：设计一个表单，form的属性添加 enctype="multipart/form-data"，设计一个iframe，设为隐藏。form的target等于iframe的name;

servlet部分：文件上传用的Commons-FileupLoad，需要两个Jar，commons-fileupload和commons-io,少了第二个会报出找不到类的异常；

第一个servlet处理上传，及把上传进度保存到session,第二个servlet处理ajax请求,回传session保存的进度值；

进度条：可以用ajax拿到回传的进度值，改变图片的width实现变化；

jsp代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title><link rel="stylesheet" type="text/css" href="css/progress.css"><script type="text/javascript" src="js/ul.js" charset="gbk"></script></head><body><form action="UploadServlet" name="f1" id="f1" method="post" enctype="multipart/form-data" target="if"><input type="file" name="file1" /><br><br><input type="reset" name="res1" value="重置"/><input type="button" name="but1" value="提交" onclick="go();"/></form><br><div id="pro" class="pro" align="left"><img alt="" src="photo/progress.png" width="0" height="15" id="imgpro"></div>        <span id="prop" style="width:15px;height:15px;display: none;">0%</span><iframe id="if" name="if" src="" style="display: none"></iframe></body></html>

这是index.jsp里的代码：

提交后还在当前页显示进度，所以要用到iframe，提交后的返回放到隐藏的iframe里，不影响页面效果；

css代码：

.pro{height:15px;width:500px;background: #FFFFF0;border: 1px solid #8FBC8F;margin: 0;padding: 0;display:none;position: relative;left:25px;float:left;}

js代码

function go(){f1.submit();document.getElementById("pro").style.display="block";document.getElementById("prop").style.display="";timer=setInterval("getP()",50);}var xmlHttpRequest;function getP(){if(window.XmlHttpRequest){xmlHttpRequest=new XmlHttpRequest();}else{xmlHttpRequest=new ActiveXObject("Microsoft.XMLHTTP");}xmlHttpRequest.onreadystatechange=callBack;url="getProgressServlet";xmlHttpRequest.open("post",url,true);xmlHttpRequest.setRequestHeader("Content-type","application/x-www-form-urlencoded");xmlHttpRequest.send("&timeStamp="+(new Date()).getTime());}//回调函数function callBack(){if(xmlHttpRequest.readyState==4 && xmlHttpRequest.status==200){result=xmlHttpRequest.responseText;var result=result.replace(/(^\s*)|(\s*$)/g, "");var res=result.split(",");var flag=res[1];var per=parseInt(res[0]);var err=res[2];document.getElementById("imgpro").style.width=per*5+"px";document.getElementById("prop").innerHTML=per+"%";if(flag=="OK"){window.clearInterval(timer);alert("上传成功！");document.getElementById("pro").style.display="none";document.getElementById("prop").innerHTML="";f1.reset();}if(err!=""||err.length>0){window.clearInterval(timer);alert(err);}if(flag==null){window.clearInterval(timer);}}}

flag为上传成功标记，err为出错标记；

servlet代码（UploadServlet）：

package com.ul.servlet;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;import java.util.Iterator;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;public class UploadServlet extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置编码格式为utf-8request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");//获取session，保存进度和上传结果，上传结果初始值为NOK，当为Ok表示上传完成HttpSession session=request.getSession();session.setAttribute("prog", "0");session.setAttribute("result", "NOK");session.setAttribute("error", "");String error="";//给上传的文件设一个最大值，这里是不得超过50MBint maxSize=50*1024*1024;//创建工厂对象和文件上传对象DiskFileItemFactory factory=new DiskFileItemFactory();ServletFileUpload upload=new ServletFileUpload(factory);try {//解析上传请求List items=upload.parseRequest(request);Iterator itr=items.iterator();while(itr.hasNext()){FileItem item=(FileItem)itr.next();//判断是否为文件域if(!item.isFormField()){if(item.getName()!=null&&!item.getName().equals("")){//获取上传文件大小和文件名称long upFileSize=item.getSize();String fileName=item.getName();if(upFileSize>maxSize){error="您上传的文件太大了，请选择不超过50MB的文件!";break;}//此时文件暂存在服务器的内存中，构造临时对象File tempFile=new File(fileName);//指定文件上传服务器的目录及文件名称File file=new File("f:\\temp",tempFile.getName());//构造输入流读文件InputStream is=item.getInputStream();int length=0;byte[] by=new byte[1024];double persent=0;FileOutputStream fos=new FileOutputStream(file);PrintWriter out=response.getWriter();while((length=is.read(by))!=-1){//计算文件进度persent+=length/(double)upFileSize*100D;fos.write(by, 0, length);session.setAttribute("prog", Math.round(persent)+"");Thread.sleep(10);}fos.close();Thread.sleep(1000);}else{error="没选择上传文件！";}}}} catch (Exception e) {e.printStackTrace();error="上传文件出现错误:"+e.getMessage();}if(!error.equals("")){session.setAttribute("error", error);}else{session.setAttribute("result", "OK");}}}

不要忘记commons-io包

servlet代码（getProgressServlet）：

package com.ul.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class getProgressServlet extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");HttpSession sesson=request.getSession();PrintWriter out=response.getWriter();String str=(String)sesson.getAttribute("prog")+"";String res=(String)sesson.getAttribute("result");String err=(String)sesson.getAttribute("error");System.out.println(str+","+res+","+err);out.print(str+","+res+","+err);out.flush();out.close();}}

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