欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识！
您现在的位置是： 首页

Servlet的文件下载案例

程序员文章站 2022-06-02 13:54:37
...

文件上与下载

案例需求分析与步骤

Servlet的文件下载案例

下载页面的代码实现

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <a href="/08_response/downloadServlet?filename=素描1.jpg">素描风景</a>
    <a href="/08_response/downloadServlet?filename=夏天的风.mp3">夏天的风</a>
</body>
</html>

文件下载的Servlet代码部分

package pers.cb.web.download;

import pers.cb.web.utils.DownLoadUtils;

import javax.servlet.ServletContext;
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.io.FileInputStream;
import java.io.IOException;

@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.获取请求参数,文件名称
        String filename = request.getParameter("filename");
        //2.使用字节输入流加载文件进内存
        //2.1找到文件服务器路径
        ServletContext servletContext = this.getServletContext();
        //判断文件类型来找到文件服务器路径
        String realPath = null;
        if (filename.endsWith(".jpg"))
        {
            realPath = servletContext.getRealPath("/img/" + filename);
        }
        if (filename.endsWith(".mp3"))
        {
            realPath = servletContext.getRealPath("/music/" + filename);
        }
        System.out.println(realPath);
        //2.2用字节流关联
        FileInputStream fis = new FileInputStream(realPath);

        //3.设置response的响应头
        //3.1设置响应头类型:content-type
        String mimeType = servletContext.getMimeType(filename);//获取文件的mime类型
        response.setHeader("content-type",mimeType);
        //response.setContentType("text/html;charset=utf-8");

        //解决中文文件名问题
        //1.获取user-agent请求头
        String agent = request.getHeader("user-agent");
        //2.使用工具类方法编码文件名即可
        filename = DownLoadUtils.getFileName(agent, filename);

        //3.2设置响应头打开方式
        response.setHeader("content-disposition","attachment;filename=" + filename);

        //4.将输入流的数据写出到输出流中
        ServletOutputStream sos = response.getOutputStream();
        byte[] bytes = new byte[1024 * 8];
        int len = 0;
        while((len = fis.read(bytes)) != -1)
        {
            sos.write(bytes,0,len);
        }
        fis.close();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

中文文件名的工具类

package pers.cb.web.utils;

import sun.misc.BASE64Encoder;

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

public class DownLoadUtils {
    public static String getFileName(String agent,String filename) throws UnsupportedEncodingException {
        if (agent.contains("MSIE"))
        {
            //  IE浏览器
            filename = URLEncoder.encode(filename,"utf-8");
            filename = filename.replace("+"," ");
        } 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{
            // 其他浏览器
            filename = URLEncoder.encode(filename,"utf-8");
        }
        return filename;
    }
}

相关标签： servlet http web java

上一篇： 文件上传Content-disposition中Attachment和inline的区别

下一篇： merge-two-sorted-lists

推荐阅读