下载文件总结

r囧r小猫 2023-10-17 18:37 20阅读 0赞

一、遍历文件并将其放进request域中

package com.hong.controler;
    
    import java.io.File;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class ListFile extends HttpServlet {
    
    	public void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    //将文件放进list集合里面
    		List<String> filesName = new ArrayList<String>();
    		String basePath = getServletContext().getRealPath("/upload");
    		File file = new File(basePath);
    		//获取子文件
    		File sons[] = file.listFiles();
    		for(File son:sons ){
    			if(son.isFile()){
    				String sonName = son.getAbsolutePath();
    				//获取文件的简单的名字
    				String realSonName = sonName.substring(sonName.lastIndexOf("\\")+1);
    				filesName.add(realSonName);
    			}
    		}
    		request.setAttribute("filesName", filesName);
    		request.getRequestDispatcher("/listDownload.jsp").forward(request, response);
    	}
    
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    doGet(request,response);
    	}
    
    }

二、跳转到下载列表页面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
    
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
        
        <title>listDownload.jsp</title>
        
      </head>
      
      <body>
        hello,你好. <br>
        <c:forEach var="en" items="${filesName }" varStatus="vs">
        <tr>
        <td>${vs.count}</td>
        <td>${en }</td>
        <td><a href="${pageContext.request.contextPath }/servlet/Download?fileName=${en}">下载</a></td>
        </tr>
        <br>
        </c:forEach>
      </body>
    </html>

三、通过超链接后下得到文件

package com.hong.controler;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class Download extends HttpServlet {
    
    	public void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    
    		String fileName = request.getParameter("fileName");
    		String basePath = getServletContext().getRealPath("upload");
    		InputStream in = new FileInputStream(new File(basePath+"\\"+fileName));
    		response.setHeader("Content-Disposition", "attachment;filename="+fileName);
    		OutputStream out = response.getOutputStream();
    		byte buffer[] = new byte[1024];
    		int len = -1;
    		while((len = in.read(buffer))!=-1){
    			out.write(buffer, 0, len);
    		}
    		out.close();
    		in.close();
    	}
    
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		doGet(request,response);
    	}
    
    }

总结：

超链接a的连接时href而不是link

response.setHeader("Content-Disposition", "attachment;filename="+fileName);设置头部时候记得要是首字母大写

InputStream in = new FileInputStream(new File(basePath+"\\\\"+fileName));