JavaWeb案例： 文件下载 基于tomcat8 默认编码为UTF-8 

 1 package cn.itcast.download;
 2 
 3 import javax.servlet.ServletException;
 4 import javax.servlet.ServletOutputStream;
 5 import javax.servlet.annotation.WebServlet;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 import java.io.FileInputStream;
10 import java.io.IOException;
11 
12 @WebServlet("/001")
13 public class DownloadServlet extends HttpServlet {
14     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
15         //获取资源名
16         String filename = request.getParameter("filename");
17         //获取资源对应输入流
18         FileInputStream fis = new FileInputStream(request.getServletContext().getRealPath("/download/" + filename));
19         //告知类型
20         response.setContentType(request.getServletContext().getMimeType(filename));
21         //告知下载
22         response.setHeader("content-disposition", "attachment;filename=" + filename);
23         //获取响应输出流
24         ServletOutputStream sos = response.getOutputStream();
25         //写数据
26         byte[] bys = new byte[1024 * 8];
27         int len;
28         while((len = fis.read(bys)) != -1){
29             sos.write(bys, 0, len);
30         }
31         //释放资源
32         fis.close();
33     }
34 
35     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
36         doPost(request, response);
37     }
38 }
版本1 直接写逻辑，不考虑乱码
 1 package cn.itcast.download;
 2 
 3 import javax.servlet.ServletException;
 4 import javax.servlet.ServletOutputStream;
 5 import javax.servlet.annotation.WebServlet;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 import java.io.FileInputStream;
10 import java.io.IOException;
11 import java.net.URLEncoder;
12 import java.util.Base64;
13 
14 @WebServlet("/download")
15 public class DownloadServlet2 extends HttpServlet {
16     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
17         //获取资源名
18         String filename = request.getParameter("filename");
19         //获取资源对应输入流
20         FileInputStream fis = new FileInputStream(request.getServletContext().getRealPath("/download/" + filename));
21         //告知类型
22         response.setContentType(request.getServletContext().getMimeType(filename));
23         //告知下载
24         //处理响应头乱码，浏览器兼容性问题
25         String agent = request.getHeader("user-agent");
26         String fileNameEnc = null;
27         if(agent.contains("MSIE")){
28             fileNameEnc = URLEncoder.encode(filename,"UTF-8").replace("+", " ");
29         }else if(agent.contains("Firefox")){
30             fileNameEnc = "=?utf-8?B?"
31                     + Base64.getEncoder().encodeToString(filename.getBytes("UTF-8"))
32                     + "?=";
33         }else{
34             fileNameEnc = URLEncoder.encode(filename,"UTF-8");
35         }
36         response.setHeader("content-disposition", "attachment;filename=" + fileNameEnc);
37         //获取响应输出流
38         ServletOutputStream sos = response.getOutputStream();
39         //写数据
40         byte[] bys = new byte[1024 * 8];
41         int len;
42         while((len = fis.read(bys)) != -1){
43             sos.write(bys, 0, len);
44         }
45         //释放资源
46         fis.close();
47     }
48 
49     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
50         doPost(request, response);
51     }
52 }
版本2 解决响应头乱码。content-disposition:attachment;filename=xxx

 

posted @ 2019-05-08 17:05  没有理由不会呀  阅读(384)  评论(0)  编辑  收藏  举报