Servlet完成文件下载的代码的实现

public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1.接收参数
String filename = request.getParameter("filename");
// 2.完成文件下载:
// 2.1设置Content-Type头
String type = this.getServletContext().getMimeType(filename);
response.setHeader("Content-Type", type);
// 2.2设置Content-Disposition头
response.setHeader("Content-Disposition", "attachment;filename="+filename);
// 2.3设置文件的InputStream.
String realPath = this.getServletContext().getRealPath("/download/"+filename);
InputStream is = new FileInputStream(realPath);
// 获得response的输出流:
OutputStream os = response.getOutputStream();
int len = 0;
byte[] b = new byte[1024];
while((len = is.read(b))!= -1){
os.write(b, 0, len);
}
is.close();
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}

}