SmartUpload组件+Servlet+Jsp实现文件的上传和下载

SmartUploadServlet.java

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import com.jspsmart.upload.*;;
public class SmartUploadServlet extends HttpServlet {
    private ServletConfig config;
    //初始化Servlet
    final public void init(ServletConfig config)
                throws ServletException{
    this.config=config;
    }
    //处理GET请求
public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {

        this.doPost(request, response);
}
//响应POST请求
public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        //获取PrintWriter对象
   PrintWriter out = response.getWriter();
   out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
   out.println("<HTML>");
   out.println("<HEAD><TITLE>A Servlet</TITLE></HEAD>");
   out.println("<BODY bgcolor='white'><center><br>");
   out.println("<br><h1>jspSmartUpload</h1>");
   out.println("<hr><br>");
   //新建一个SmartUpload对象
   SmartUpload mySmartUpload=new SmartUpload();
   try{
    //上传初始化
    mySmartUpload.initialize(config, request, response);
    //设定每个上传文件的最大长度
    mySmartUpload.setMaxFileSize(1*512*1024);
    //设定总上传数据的长度
    mySmartUpload.setTotalMaxFileSize(1*1024*1024);
    //设定允许上传的文件的类型,只允许上传java,doc,txt文件
    mySmartUpload.setAllowedFilesList("java,doc,txt");
    //设定禁止上传的文件的类型,禁止上传带有exe,bat文件
    mySmartUpload.setDeniedFilesList("exe,bat");
    //上传文件
    mySmartUpload.upload();
    //将上传文件全部保存到指定目录
    int count=mySmartUpload.save("/");
    out.println(//利用Request对象获取参数之值
      mySmartUpload.getRequest().getParameter("paramete")+"&nbsp;");
    //显示处理结果
    out.println("<font color=red>"+count+"</font>&nbsp;File Upload!<br>");
    //处理每个上传文件
    for(int i=0;i<mySmartUpload.getFiles().getCount();i++)
    {
     com.jspsmart.upload.File file
     =mySmartUpload.getFiles().getFile(i);
     //判断用户是否选择了文件
        if(!file.isMissing()){
          //打印文件名
         out.println("File Name:&nbsp;<font color=red>"
           +file.getFileName()+"</font><br>");
         //打印文件扩展名
         out.println("File ExtName:&nbsp;<font color=red>"
           +file.getFileExt()+"</font><br>");
         //打印文件路径,包括目录
         out.println("Path:&nbsp;<font color=red>"
           +file.getFilePathName()+"</font><br>");
         //另存到以Web应用程序的根目录为文件根目录的目录下
         //(声明一下：在Myeclipse中，该目录位于工程下的.metadata/.me_tcat/webapps/该工程目录/upload/)
         file.saveAs("/upload/"+file.getFileName(),mySmartUpload.SAVE_VIRTUAL);
         //另存到操作系统的根目录为文件根目录的目录下
         file.saveAs("F:\\my tool\\project\\SmartUpload\\temp\\"+file.getFileName(),
           mySmartUpload.SAVE_PHYSICAL);
        }
    }
   }catch(Exception e){//异常处理
    //打印自定义异常信息
    out.println("Unanable to upload the file.<br>");
    out.println("Please Check The File Type");
   }
   out.println("</center></BODY>");
   out.println("</HTML>");
     }
}

　　upload.jsp

<%@ page contentType="text/html;charset=gb2312"%>
<html>
<head>
    <title>jspSmartUpload组件文件上传</title>
</head>
<body>
    <br><br><center>
    <font size="5" color="#ff0000"><b>jspSmartUpload组件文件上传</b></font><br>
    <form name="uploadForm" enctype="multipart/form-data"
          method="post" action="servlet/SmartUploadServlet">
       <table border="0" align="center" cellpadding="2" cellspacing="2" bgcolor="snow">
       <input type="hidden" name="paramete" value="OK!">
          <tr>
             <td>
             <div align="center">上传文件1:</div>
             </td>
             <td><div align="center">
                <input type="file" name="file1" size="25" maxlength="80">
             </div></td>
          </tr> 
          <tr>
             <td>
             <div align="center">上传文件2:</div>
             </td>
             <td><div align="center">
                <input type="file" name="file2" size="25" maxlength="80">
             </div></td>
          </tr>
          <tr width="100%">
             <td>
             <div align="center"><input type="submit" value="上传文件"> 
             <input type="reset" value="清除"></div>
             </td>
          </tr> 
       </table>
    </form></center>   
</body>
</html>

　　SmartDownloadServlet.java

　　　　

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import com.jspsmart.upload.*;;
public class SmartDownloadServlet extends HttpServlet {
    private ServletConfig config;
    //初始化Servlet
    final public void init(ServletConfig config)
                throws ServletException{
    this.config=config;
    }
    //处理GET请求
public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        this.doPost(request, response);
}
//响应POST请求
public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        //获取PrintWriter对象
   //PrintWriter out = response.getWriter();    //这里会出现异常
   out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
   out.println("<HTML>");
   out.println("<HEAD><TITLE>A Servlet</TITLE></HEAD>");
   out.println("<BODY bgcolor='white'><center><br>");
   out.println("<br><h1>jspSmartDownload</h1>");
   out.println("<hr><br>");
   //新建一个SmartUpload对象
   SmartUpload mySmartUpload=new SmartUpload();
   try{
    //上传初始化
    mySmartUpload.initialize(config, request, response);
         String fileName=request.getParameter("fileName");
         //设定contentDisposition为null以禁止浏览器
         //自动打开文件
         //保证单击链接后是下载文件，若不设定，则
         mySmartUpload.setContentDisposition(null);
    //下载文件
    mySmartUpload.downloadFile("/upload/"+fileName);
   }catch(Exception e){//异常处理
    //打印自定义异常信息
    //out.println("Download Fail.<br>");
    //out.println(e.toString());
    //想要打印信息可参考下面的补充说明
   }
   //out.println("</center></BODY>");
   //out.println("</HTML>");
     }
}

　　download.jsp

<%@ page contentType="text/html;charset=gb2312"%>
<html>
<head>
    <title>jspSmartUpload组件下载文件</title>
</head>
<body>
    <br><br><center>
    <font size="5" color="#ff0000"><b>jspSmartUpload组件下载文件</b></font><br>
    <form name="uploadForm" enctype="multipart/form-data"
          method="post" action="servlet/SmartDownloadServlet">
       <table border="0" align="center" cellpadding="2" cellspacing="2" bgcolor="snow">
          <tr>
             <td>
             <div align="center">
               <a href="servlet/SmartDownloadServlet?fileName=1.jpg">文件1</a>
             </div>
             </td>
              <td>
             <div align="center">
               <a href="servlet/SmartDownloadServlet?fileName=2.jpg">文件2</a>
             </div>
             </td>
          </tr> 
       </table>
    </form></center>   
</body>
</html>

　

对 jspSmartUpload上传下载全攻略 的一点补充和说明!!

如果要在servlet中使用jspSmartUpload.则须改为
 // 上传初始化
    su.initialize(getServletConfig(),request,response);


截取同表单一起传过来的表单元素.并使其成中文.
operStr =new String(su.getRequest().getParameter("act").getBytes("GBK"),"gb2312");

下载出错:getWriter() has already been called  的解决方法
1.必须用SERVLET下载.
2.//    PrintWriter out = response.getWriter();令这一行失效.
分析:个人认为,因为在组件中,已经打开过一次response.getWriter了.所以再次打开
          时会出现调用重复的现象.于是出错!!!

解决方法:如果要在页面打印出错信息,可将PrintWriter out = response.getWriter();设

                  成局部变量.例:.....catch(...){PrintWriter out = response.getWriter();}如果不用,则可以不设.　





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原文地址：https://www.cnblogs.com/macula/p/2143985.html