解决文件名是中文时的下载乱码问题

在文件下载时候通常文件名是中文时会出现乱码问题，有两种解决方案
第一种（在页面对代码进行编码）不推荐使用
jsp代码

<%@page import="java.net.URLEncoder"%>
<%@ 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>文件下载</title>
</head>
<body>
<a href="/chapter12/DownloadServlet?filename=timg.jpg">文件下载-----文件名是英文</a>
<br><br><br><br><br>
<a href="/chapter12/DownloadServlet?filename=<%=URLEncoder.encode("解决办法.docx", "utf-8")%>">文件下载----文件名是中文第一种方案</a>
<br><br><br><br><br>
</body>
</html>

DownloadServlet代码

package com.zch.upload;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 
 * @ClassName: DownloadServlet.java
 * @Description: 文件的下载
 * @author 萌城小小小少年
 * @version V1.0
 * @Date 2019年2月15日 下午7:23:35
 *
 */
public class DownloadServlet extends HttpServlet {

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 处理响应中文的乱码问题
		response.setContentType("text/html;charset=utf-8");
		// 1.获取下载文件的名称
		String filename = request.getParameter("filename");
		//处理get请求的中文乱码问题
		filename=new String(filename.getBytes("iso-8859-1"),"utf-8");
		// 2.获取文件的mime类型
		String fileType = getServletContext().getMimeType(filename);
		// 设置两个头
		response.addHeader("Content-Type", fileType);
		//通过页面编码解决中文乱码         
		//response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename,"utf-8"));
		// 4.文件的下载
		String folder = "/download/";
		// 4.1获取文件的字节输入流
		InputStream in = getServletContext().getResourceAsStream(folder + filename);
		// 4.2获取文件的字节输出流
		OutputStream out = response.getOutputStream();
		// 5.流的对接
		byte[] buffer = new byte[1024];
		int len = 0;
		while ((len = in.read(buffer)) != -1) {
			out.write(buffer, 0, len);
		}
		// 关闭流
		out.close();
		in.close();
	}

	/**
	 * @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);
	}

}

这种方法不推荐使用，因为不适用所有的浏览器，比如火狐有时候会出现以下问题
在这里插入图片描述
第二种方案（推荐使用）
jsp代码

<%@page import="java.net.URLEncoder"%>
<%@ 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>文件下载</title>
</head>
<body>
<a href="/chapter12/DownloadServlet?filename=timg.jpg">文件下载-----文件名是英文</a>
<br><br><br><br><br>
<a href="/chapter12/DownloadServlet?filename=<%=URLEncoder.encode("解决办法.docx", "utf-8")%>">文件下载----文件名是中文第一种方案</a>
<br><br><br><br><br>
<a href="/chapter12/DownloadServlet?filename=解决办法.docx">文件下载----文件名是中文第二种方案</a>
</body>
</html>

DownUtil代码（这段代码为模板代码，不需要记忆理解即可）

package com.zch.upload;

import sun.misc.*;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import javax.servlet.http.HttpServletRequest;

public class DownUtils {
	public static String filenameEncoding(String filename, HttpServletRequest request) throws UnsupportedEncodingException {
		// 获得请求头中的User-Agent
		String agent = request.getHeader("User-Agent");
		// 根据不同的客户端进行不同的编码

		if (agent.contains("MSIE")) {
			// IE浏览器
			filename = URLEncoder.encode(filename, "utf-8");
		} else if (agent.contains("Firefox")) {
			// 火狐浏览器
			BASE64Encoder base64Encoder = new BASE64Encoder();
			filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";
		} else {
			// 其它浏览器
			filename = URLEncoder.encode(filename, "utf-8");
		}
		return filename;
	}
}

DownloadServlet代码

package com.zch.upload;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 
 * @ClassName: DownloadServlet.java
 * @Description: 文件的下载
 * @author 萌城小小小少年
 * @version V1.0
 * @Date 2019年2月15日 下午7:23:35
 *
 */
public class DownloadServlet extends HttpServlet {

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 处理响应中文的乱码问题
		response.setContentType("text/html;charset=utf-8");
		// 1.获取下载文件的名称
		String filename = request.getParameter("filename");
		//处理get请求的中文乱码问题
		filename=new String(filename.getBytes("iso-8859-1"),"utf-8");
		// 2.获取文件的mime类型
		String fileType = getServletContext().getMimeType(filename);
		String name=DownUtils.filenameEncoding(filename, request);
		// 设置两个头
		response.addHeader("Content-Type", fileType);
		response.addHeader("Content-Disposition", "attachment;filename=" +name);
		// 4.文件的下载
		String folder = "/download/";
		// 4.1获取文件的字节输入流
		InputStream in = getServletContext().getResourceAsStream(folder + filename);
		// 4.2获取文件的字节输出流
		OutputStream out = response.getOutputStream();
		// 5.流的对接
		byte[] buffer = new byte[1024];
		int len = 0;
		while ((len = in.read(buffer)) != -1) {
			out.write(buffer, 0, len);
		}
		// 关闭流
		out.close();
		in.close();
	}

	/**
	 * @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);
	}

}

解决文件名是中文时的下载乱码问题

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