Response下载文件

下载流程

• resp.setHeader("Content-Disposition", "attachment;filename="+filesName);（setHeader详解）
• 创建输入流（不要用getServletContext().getRealPath(path)）原因
• 输出流

public class downL extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String path = "/WEB-INF/classes/img.png";
        this.getServletContext().getRealPath(path)
        String filesName = path.substring(path.lastIndexOf("/")+1);
        resp.setHeader("Content-Disposition", "attachment;filename="+filesName);
        InputStream in = this.getServletContext().getResourceAsStream(path);//和获取properties类似
        int len = 0;
        byte[] buffer = new byte[1024];
        ServletOutputStream out = resp.getOutputStream();
        while ((len = in.read(buffer))>0){
            out.write(buffer,0,len);
        }
        in.close();
        out.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}