Java 文件下载功能 解决中文乱码

时间：2021-06-20 09:40:34

Html部分

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

    <a href="http://localhost:8080/webdemojava/download1?filename=a.flv" class="downloadbtn">a.flv</a>

    <a href="http://localhost:8080/webdemojava/download1?filename=a.jpg" class="downloadbtn">a.jpg</a>

    <a href="http://localhost:8080/webdemojava/download1?filename=a.mp3" class="downloadbtn">a.mp3</a>

    <a href="http://localhost:8080/webdemojava/download1?filename=a.mp4" class="downloadbtn">a.mp4</a>

    <a href="http://localhost:8080/webdemojava/download1?filename=a.txt" class="downloadbtn">a.txt</a>

    <a href="http://localhost:8080/webdemojava/download1?filename=a.z1ip" class="downloadbtn">a.z1ip</a>

</body>

</html>

Java代码

package action;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.URLEncoder;

import javax.servlet.ServletException;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.jasper.tagplugins.jstl.core.Out;

import sun.misc.BASE64Encoder;

public class DownLoad1 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public DownLoad1() {

        super();

        // TODO Auto-generated constructor stub

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String filename = request.getParameter("filename"); //获取发送过来的文件名

        filename = new String(filename.getBytes("ISO8859-1"),"UTF-8"); //解决传过来的文件名是中文.会变乱码的问题

        //获得请求头中的 User-Agent

        String agent = request.getHeader("User-Agent");

        //根据不同的客户的 进行不同的编码 .解决下载的文件 中文 没名字

        String filenameEncoder = "";

        if (agent.contains("MSIE")) {

            // IE浏览器

            filenameEncoder = URLEncoder.encode(filename, "utf-8");

            filenameEncoder = filenameEncoder.replace("+", " ");

        } else if (agent.contains("Firefox")) {

            // 火狐浏览器

            BASE64Encoder base64Encoder = new BASE64Encoder();

            filenameEncoder = "=?utf-8?B?"

                    + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";

        } else {

            // 其它浏览器

            filenameEncoder = URLEncoder.encode(filename, "utf-8");

        }

        String realPath = this.getServletContext().getRealPath("/download/"+filename); //相对路径变绝对路径

        InputStream in = null;

        try {

            in = new FileInputStream(realPath); //读到要下载的文件.并做检测文件是否存在

        } catch (Exception e) {

            // TODO: handle exception

            e.printStackTrace();

        }

        if (in == null) {

            response.setContentType("text/html;charset=UTF-8");

            response.getWriter().append("没有找到该文件");

            return;

        }

        ServletOutputStream out = response.getOutputStream();

        response.setContentType(this.getServletContext().getMimeType(filename)); //设置返回的文件类型

        response.setHeader("Content-Disposition", "attachment;filename="+filenameEncoder); //告诉客户的文件以附件类型打开(下载)

        int len = 0;

        byte[] buffer = new byte[1024];

        while ((len=in.read(buffer))>0) {

            out.write(buffer, 0, len);

        }

        in.close();

        out.close();

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);

    }

}

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