<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<!--定义超链接跳转到对应的Servlet并且携带文件名参数-->
<a href="/DownloadTest/downloadServlet?filename=1.jpg">点击下载图片1</a><br>
<a href="/DownloadTest/downloadServlet?filename=2.jpg">点击下载图片2</a><br>
<a href="/DownloadTest/downloadServlet?filename=3.jpg">点击下载图片3</a><br>
</body>
</html>
@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1. 获取请求参数(即文件名称)
String filename=request.getParameter("filename");
//2. 使用字节输入流加载文件进内存
//2.1 获取文件真实路径
String path=this.getServletContext().getRealPath("/img/"+filename); //通过ServletContext对象获取真实路径
//2.2 加载进内存
FileInputStream fis=new FileInputStream(path);
//3. 设置响应头数据
//3.1 设置content-type(需要利用ServletContext获取文件的MIME类型)
String mimeType=this.getServletContext().getMimeType(filename);
response.setHeader("content-type",mimeType);
//3.2 设置content-disposition(文件的打开方式,以附件形式打开。filename属性表示保存文件的名称)
response.setHeader("content-disposition","attachment;filename="+filename);
//4. 将文件内容(输入流)写入输出流中
ServletOutputStream sos=response.getOutputStream();
int len=0;
byte[] buff=new byte[1024*8];
while((len=fis.read(buff))!=-1){
sos.write(buff,0,len);
}
fis.close();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}