Response + Servlet实现文件下载功能

本文详细介绍了在Java Web环境中如何解决文件下载时遇到的各种问题,包括文件名乱码、文件类型识别及直接下载功能实现。通过使用request.getParameter()、getServletContext().getMimeType()和response.setContentType()等方法,结合不同浏览器的编码特性,确保了跨浏览器的文件下载体验。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

1、获取文件名:request.getParameter()方法

2、获取文件类型名称:getServletContext().getMimeType()方法

3、设置响应文件类型名称(解决文件类型无法识别问题):response.setContentType()方法

4、设置浏览器以附件形式进行识别(可以实现直接弹窗下载):response.setHeader("Content-Disposition", "attachment;filename="+文件名);

5、请求参数中文乱码解决(这是由于使用较高版本Tomcat导致):配置tomcat的catalina.properties(最后一行),添加或者修改以下语句:

tomcat.util.http.parser.HttpParser.requestTargetAllow=|{}
或
org.apache.tomcat.util.buf.UDecoder.ALLOW_ENCODED_SLASH=true

还有一种解决办法是前台代码使用js提供的encodeURI方法对url进行转义encodeURI(URI)。

还可以在后端对文件名进行编码:

//获取客户信息
		String agent = request.getHeader("User-Agent");
		//记录编码之后的名字
		String filenameEncoder="";
		if(agent.contains("MSIE")) {
			//IE浏览器编码
			filenameEncoder = java.net.URLEncoder.encode(FileName,"UTF-8");
			filenameEncoder = filenameEncoder.replace("+", " ");
		}else if(agent.contains("Firefox")) {
			//火狐浏览器编码
			BASE64Encoder base64Encoder = new BASE64Encoder();
			filenameEncoder = "=?UTF-8?B?" + base64Encoder.encode(FileName.getBytes("UTF-8")) + "?=";
			
		}else {
			//基于Chromium内核的浏览器
			filenameEncoder = java.net.URLEncoder.encode(FileName,"UTF-8");
		}
		
		//设置浏览器以附件形式进行识别(可以实现直接下载相应文件)
		response.setHeader("Content-Disposition", "attachment;filename="+filenameEncoder);

主要代码如下:

package com.HttpServlet.Index;
 
import java.io.FileInputStream;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.net.URLEncoder.*;
 
import org.apache.catalina.util.URLEncoder;
 
import sun.misc.BASE64Encoder;
 
/**
 * Servlet implementation class DownLoadServlet
 */
@WebServlet("/DownLoadServlet")
public class DownLoadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public DownLoadServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
 
	/**
	 * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setContentType("text/html;charset=UTF-8");
		
		//获取文件名
		String FileName = request.getParameter("filename");
		
		//把乱码进行转码
		byte[] bytes = FileName.getBytes("ISO8859-1");
		FileName = new String(bytes,"UTF-8");
		//获取文件类型名称
		String mimeType = this.getServletContext().getMimeType(FileName);
		//设置响应文件类型名称,这样可以解决文件类型无法识别问题
		response.setContentType(mimeType);
		
		//获取客户信息
		String agent = request.getHeader("User-Agent");
		//记录编码之后的名字
		String filenameEncoder="";
		if(agent.contains("MSIE")) {
			//IE浏览器编码
			filenameEncoder = java.net.URLEncoder.encode(FileName,"UTF-8");
			filenameEncoder = filenameEncoder.replace("+", " ");
		}else if(agent.contains("Firefox")) {
			//火狐浏览器编码
			BASE64Encoder base64Encoder = new BASE64Encoder();
			filenameEncoder = "=?UTF-8?B?" + base64Encoder.encode(FileName.getBytes("UTF-8")) + "?=";
			
		}else {
			//基于Chromium内核的浏览器
			filenameEncoder = java.net.URLEncoder.encode(FileName,"UTF-8");
		}
		
		//设置浏览器以附件形式进行识别(可以实现直接下载相应文件)
		response.setHeader("Content-Disposition", "attachment;filename="+filenameEncoder);
 
		//拼接文件路径
		String FilePath = this.getServletContext().getRealPath("DownLoad/"+FileName);
		
		//根绝Path加载文件
		
		FileInputStream in = new FileInputStream(FilePath);
		
		//获取响应输出流
		ServletOutputStream out = response.getOutputStream();
		
		byte[] buffer = new byte[1024];
		int length = 0;
		while( (length = in.read(buffer)) !=-1 ) {
			out.write(buffer,0,length);
		}
		
		//关闭文件流
		in.close();
		out.close();
	}
 
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}
 
	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
		
		String FileName = request.getParameter("filename");
		System.out.println(FileName);
		
	}
 
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>首页</title>
</head>
<body>
<hr>
<h3>下载功能</h3>
<a href="/JWDemo/DownLoadServlet?filename=宋兆恒.zip">Hern图片</a>
</body>
</html>

 

本文原文地址:https://blog.youkuaiyun.com/qq_36761831/article/details/86485166

评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值