java中用HttpServletResponse实现浏览器的文件下载
搬运自这篇博客。
实现效果
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步骤
1. 将文件放在resources文件包下
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2. FileServlet类实现代码
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| public class FileServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.要获取下载文件的路径
String realPath = "E:\\开源项目\\demo\\javaweb-02-servlet\\response\\src\\main\\resources\\123.png";
System.out.println("下载文件的位置"+realPath);
//2.下载的文件名是啥,截取文件名
String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
//3.设置让浏览器支持(Content-Disposition)下载我们需要的东西,如果文件名字为中文，需要转码，URLEncoder.encode设置文件名编码
resp.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(fileName,"utf-8"));
//4.获取下载文件的输入流
FileInputStream in = new FileInputStream(realPath);
//5.创建缓冲区
int len = 0;
byte[] buffer = new byte[1024];
//6.获取OutputStream对象
ServletOutputStream out = resp.getOutputStream();
//7.将FileOutputStream流写入到buffer缓冲区，使用OutputStream将缓冲区的数据输出到客户端
while ((len = in.read(buffer)) > 0){
out.write(buffer,0,len);
}
//关闭流
in.close();
out.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
|
3. web.xml设置
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| <?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0"
metadata-complete="true">
<!-- Servlet注册，下载文件-->
<servlet>
<servlet-name>fileDown</servlet-name>
<servlet-class>com.hwh.servlet.FileServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>fileDown</servlet-name>
<url-pattern>/fileDown</url-pattern>
</servlet-mapping>
</web-app>
|
