首先确定HTML页面上的编码格式 我这里是UTF-8

  1. <meta http-equiv="content-type" content="text/html;charset=utf-8">
  • 创建类继承HttpServlet ；
  • 重写doGet或doPost，具体使用哪个看业务需求；
    代码如下：
  1. import sun.misc.BASE64Encoder;
  2. import javax.servlet.ServletContext;
  3. import javax.servlet.ServletOutputStream;
  4. import javax.servlet.annotation.WebServlet;
  5. import javax.servlet.http.HttpServlet;
  6. import javax.servlet.http.HttpServletRequest;
  7. import javax.servlet.http.HttpServletResponse;
  8. import java.io.FileInputStream;
  9. import java.io.IOException;
  10. import java.io.UnsupportedEncodingException;
  11. import java.net.URLEncoder;
  12. import java.nio.charset.StandardCharsets;
  14. /**
  15.  * Created with IntelliJ IDEA.
  16.  * Description:
  17.  *
  18.  * @author: GanZiB
  19.  * Date: 2020-08-24
  20.  * Time: 10:16
  21.  */
  22. @WebServlet("/download")
  23. public class DownloadServlet extends HttpServlet {
  26.     @Override
  27.     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
  28.         //1.获取文件名
  29.         String fileName = req.getParameter("fileName");
  30.         //2.使用字节输入流加载文件进内存
  31.         //2.1找到文件服务器路径
  32.         ServletContext servletContext = req.getServletContext();
  33.         String realPath = servletContext.getRealPath("/res/" + fileName);
  34.         //2.2使用字节流关联
  35.         FileInputStream fis = new FileInputStream(realPath);
  36.         //3.设置response响应头
  37.         //3.1设置响应头类型：content-type
  38.         String agent = req.getHeader("user-agent");
  39.         String mimeType = servletContext.getMimeType(fileName);
  40.         resp.setHeader("content-type", mimeType);
  41.         //3.2设置响应头打开方式：content-disposition
  42.         resp.setHeader("content-disposition", "attachment;filename=" + getFileName(agent,fileName));
  43.         //4.将输入流数据写出到输出流中
  44.         ServletOutputStream sos = resp.getOutputStream();
  45.         byte[] buff = new byte[1024 * 8];
  46.         int len = 0;
  47.         while ((len = fis.read(buff)) != -1) {
  48.             sos.write(buff, 0, len);
  49.         }
  50.         fis.close();
  51.     }
  53.     /**
  54.       * 中文乱码适配不同浏览器
  55.       */
  56.     public static String getFileName(String agent, String filename) throws UnsupportedEncodingException {
  57.         if (agent.contains("MSIE")) {
  58.             // IE
  59.             filename = URLEncoder.encode(filename, "utf-8");
  60.             filename = filename.replace("+", " ");
  61.         } else if (agent.contains("Firefox")) {
  62.             //火狐
  63.             BASE64Encoder base64Encoder = new BASE64Encoder();
  64.             filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes(StandardCharsets.UTF_8)) + "?=";
  65.         }else {
  66.             filename = URLEncoder.encode(filename,"utf-8");
  67.         }
  68.         return filename;
  69.     }
  70. }
  1. <html>
  2. <head>
  3.     <meta charset="UTF-8">
  4. </head>
  6. <body>
  8. <a href="/download?fileName=图片1.jpg">图片下载</a>
  9. </body>
  11. </html>