JavaWeb--资源下载案例

图片的路径在web/img下：

网页代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <a href="/ServletTest_war_exploded/downloadServlet?filename=img1.jpg">图片1</a>

</body>
</html>

servlet代码：

@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1,获取请求参数
        String filename=request.getParameter("filename");
        //2,使用字节输入流加载文件进内存
        //2.1找到文件服务器路径
        ServletContext sc=this.getServletContext();
        String rp = sc.getRealPath("/img/" + filename);
        //2.2用字节流关联
        FileInputStream fis=new FileInputStream(rp);

        //3，设置response的响应头
        //3.1设置响应头类型content-type
        String mimeType = sc.getMimeType(filename);//获取文件的mime类型
        response.setHeader("content-type",mimeType);
        //3.2设置响应头打开方式content-disposition
        response.setHeader("content-disposition","attachment;filename="+filename);

        //4,将输入流的数据写出到输出流中
        ServletOutputStream sos=response.getOutputStream();
        byte[] buff=new byte[1024];
        int len=0;
        while((len=fis.read(buff))!=-1){
            sos.write(buff,0,len);
        }
        fis.close();
    }

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

来源：CSDN

作者：Boml.白顶

链接：https://blog.csdn.net/qq_43616001/article/details/104226396

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