java上传文件带进度条学习记录

文件上传过程中，如果我们能看到进度条会更好，实现思路是服务器端用监听器实时监听进度并存入session，客户端异步请求服务器端获得上传进度，并进行效果渲染。

效果图：

服务器端servlet:

public class UploadServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //取出监听器MyProgress在session中保存的进度信息
        String progress=(String) req.getSession().getAttribute("progress");
        //响应
        resp.getWriter().print(progress);
        //清除session中保存的数据
//        req.getSession().removeAttribute("progress");
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        DiskFileItemFactory factory=new DiskFileItemFactory();
        ServletFileUpload upload=new ServletFileUpload(factory);
        upload.setProgressListener(new MyProgressListener(req));
        try {
            List<FileItem> list = upload.parseRequest(req);
            for (FileItem fileItem : list) {
                if (fileItem.isFormField()) {//普通表单
                }else{//上传文件
                    String path=req.getRealPath("uploads");
                    String fileName=fileItem.getName();
                    File file=new File(path, fileName);
                    fileItem.write(file);
                    System.out.println("成功上传文件："+fileName);
                }
            }
        } catch (Exception e) {
            System.out.println("文件上传发生错误！");
            e.printStackTrace();
        }
    }
}

服务器端监听器：

public class MyProgressListener implements ProgressListener {
    private HttpSession session;
    public MyProgressListener(HttpServletRequest request){
        session = request.getSession();
    }
    @Override
    public void update(long pBytesRead, long pContentLength, int pItems) {
        //将数据进行格式化
        //已读取数据由字节转换为M
        double readM=pBytesRead/1024.0/1024.0;
        //已读取数据由字节转换为M
        double totalM=pContentLength/1024.0/1024.0;
        //已读取百分百
        double percent=readM/totalM;
        
        //格式化数据
        //已读取
        String readf=dataFormat(pBytesRead);
        //总大小
        String totalf=dataFormat(pContentLength);
        //进度百分百
        NumberFormat format=NumberFormat.getPercentInstance();
        String progress=format.format(percent);
        
        //将信息存入session
        session.setAttribute("progress", progress);
        
        //打印消息到控制台
        System.out.println("pBytesRead===>"+pBytesRead);
        System.out.println("pContentLength==>"+pContentLength);
        System.out.println("pItems===>"+pItems);
        System.out.println("readf--->"+readf);
        System.out.println("totalf--->"+totalf);
        System.out.println("progress--->"+progress);
    }
    /**
     * 格式化读取数据的显示
     * @param data要格式化的数据 单位byte
     * @return 格式化后的数据，如果小于1M显示单位为KB，如果大于1M显示单位为M
     */
    public String dataFormat(double data){
        String formdata="";
        if (data>=1024*1024) {//大于等于1M
            formdata=Double.toString(data/1024/1024)+"M";
        }else if(data>=1024){//大于等于1KB
            formdata=Double.toString(data/1024)+"KB";
        }else{//小于1KB
            formdata=Double.toString(data)+"byte";
        }
        return formdata.substring(0, formdata.indexOf(".")+2);
    }

}

客户端：

<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>带进度条的文件上传效果</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <style type="text/css">
        #progressBar{width: 300px;height: 20px;border: 1px #EEE solid;}
        #progress{width: 0%;height: 20px;background-color: lime;}
    </style>
    <script type="text/javascript" src="js/jquery-1.4.2.js"></script>
    <script type="text/javascript">
        function upload(){
            $("#f1").submit();
            var pro=null;
            pro=setInterval(function(){
                $.get("UploadServlet","",function(data){
                    if(data=='100%'){
                        clearInterval(pro);
                        $("#proInfo").text("上传进度：100%");
                         //更新进度条
                        $("#progress").width("100%");
                    }else{//正在上传
                        //更新进度信息
                        $("#proInfo").text("上传进度："+data);
                        //更新进度条
                        $("#progress").width(data);
                    }
                });
            },200);
        }
        
    </script>
  </head>
  
  <body>
      <iframe name="aa" style="display: none;"></iframe>
    <h2>带进度条的文件上传效果</h2>
    <form target="aa" id="f1" action="UploadServlet" method="post" enctype="multipart/form-data">
        文件：<input name="file" type="file">
        <input type="button" value="上传" onclick="upload();">
        <div id="progressBar">
            <div id="progress"></div>
        </div>
        <span id="proInfo">上传进度：0%</span>
    </form>
  </body>
</html>

说明：为了让上传后该页面不跳转，我们可以让表单跳转至一个隐藏的iframe。

其他转载的博文链接：点击打开链接

java上传文件带进度条学习记录

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