下载文件时HttpServletResponse设置响应头的Content-Disposition属性

Content-Disposition属性有两种类型

inline ：将文件内容直接显示在页面
attachment：弹出对话框让用户下载

弹出对话框下载文件

resp.setHeader("Content-Disposition", "attachment; filename="+fileName);

web.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 3     xmlns="http://java.sun.com/xml/ns/javaee" 
 4     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
 5         http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" 
 6     id="WebApp_ID" version="3.0">
 7   <display-name>DownloadDemo</display-name>
 8   <welcome-file-list>
 9     <welcome-file>index.jsp</welcome-file>
10   </welcome-file-list>
11   
12   <servlet>
13       <servlet-name>download</servlet-name>
14       <servlet-class>com.qf.servlet.DownloadServlet2</servlet-class>
15   </servlet>
16   <servlet-mapping>
17       <servlet-name>download</servlet-name>
18       <url-pattern>/download</url-pattern>
19   </servlet-mapping>
20 </web-app>

servlet类

 1 public class DownloadServlet2 extends HttpServlet {
 2 
 3     @Override
 4     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 5         //获取文件在tomcat下的路径
 6         String path = getServletContext().getRealPath("download/bb.txt");
 7 
 8         //让浏览器收到这份资源的时候， 以下载的方式提醒用户，而不是直接展示
 9         resp.setHeader("Content-Disposition", "attachment; filename=bb.txt");
10         
11         //转化成输入流
12         InputStream is = new FileInputStream(path);
13         OutputStream os = resp.getOutputStream();
14         
15         int len = 0;
16         byte[] bts = new byte[1024];
17         while ((len = is.read(bts)) != -1) {
18             os.write(bts, 0, len);
19         }
20         os.close();
21         is.close();
22     }
23 
24     @Override
25     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
26         doGet(req, resp);
27     }
28 }

url：http://localhost:8080/DownloadDemo/download

直接在浏览器页面打开文件

resp.setHeader("Content-Disposition", "inline; filename="+fileName);

修改servlet类

 1 public class DownloadServlet2 extends HttpServlet {
 2 
 3     @Override
 4     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 5         //获取文件在tomcat下的路径
 6         String path = getServletContext().getRealPath("download/bb.txt");
 7 
 8         //让浏览器收到这份资源的时候， 以下载的方式提醒用户，而不是直接展示
 9         resp.setHeader("Content-Disposition", "inline; filename=bb.txt");
10         
11         //转化成输入流
12         InputStream is = new FileInputStream(path);
13         OutputStream os = resp.getOutputStream();
14         
15         int len = 0;
16         byte[] bts = new byte[1024];
17         while ((len = is.read(bts)) != -1) {
18             os.write(bts, 0, len);
19         }
20         os.close();
21         is.close();
22     }
23 
24     @Override
25     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
26         doGet(req, resp);
27     }
28     
29 }