文件的上传与下载

最新推荐文章于 2024-12-12 20:17:37 发布

原创最新推荐文章于 2024-12-12 20:17:37 发布

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#html #java

文件上传下载案例

这里的文件选择了一张图片

1 还是先创建首页页面index.jsp lib包

<%--
  Created by IntelliJ IDEA.
  User: 86182
  Date: 2021/10/3
  Time: 8:48
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <h1>index.jsp</h1>
  <form action="uploadtest" method="post" enctype="multipart/form-data">
    姓名：<input type="text" name="uname"><br>
    图片：<input type="file" name="pic"><br>
    <input type="submit" value="上传">

  </form>
  </body>
</html>

2 点击上传后又到了熟悉的servlet包中的UploadServlet类（熟悉的@WebServlet doGet() doPost()）

package servlet;

import com.jspsmart.upload.File;
import com.jspsmart.upload.SmartUpload;
import com.jspsmart.upload.SmartUploadException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspFactory;
import javax.servlet.jsp.PageContext;
import java.io.IOException;

@WebServlet(urlPatterns ="/uploadtest")
public class UploadServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            //1。创建上传文件的对象
            SmartUpload smartUpload = new SmartUpload();

            //2.初始化上传操作
            PageContext pageContext = JspFactory.getDefaultFactory()
                    .getPageContext(this, req, resp, null, false, 1024, true);
            smartUpload.initialize(pageContext);

            //2.1设置编码
            smartUpload.setCharset("utf-8");

            //3.上传
            smartUpload.upload();

            //4.获取文件信息
            File file = smartUpload.getFiles().getFile(0);
            String fileName = file.getFileName();//可以获得文件名称
            String contentType = file.getContentType();//可以得到文件类型

            //获取文本信息
            String uname = smartUpload.getRequest().getParameter("uname");
            System.out.println("uname="+uname);


            //5.指定上传路径
            String uploadpath = "/uploadfiles/"+fileName;

            //6.保存到指定位置
            file.saveAs(uploadpath,File.SAVEAS_VIRTUAL);

            //7.跳转成功页面
            req.setAttribute("filename",fileName);//k,v形式fileName是该文件本身名称
            req.getRequestDispatcher("success.jsp").forward(req,resp);
        } catch (SmartUploadException e) {
            e.printStackTrace();
        }

    }
}

3 跳转成功后会进入success.jsp界面，

success.jsp页面代码是这么写的，有个下载的超链接

<%--
  Created by IntelliJ IDEA.
  User: 86182
  Date: 2021/10/3
  Time: 9:10
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>success.jsp</title>
</head>
<body>
<h1>success.jsp</h1>
<a href="downimg?filename=${filename}">下载</a>
<img src="uploadfiles/${filename}">

</body>
</html>

4 下载超链接点击后，又会进入servlet包里的DownServlet中，（因为是下载，所以会跳转至一个路径）

package servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;

@WebServlet(urlPatterns = "/downimg")
public class DownServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String filename = req.getParameter("filename");//获取文件名
        String path = "/uploadfiles/"+filename;//获取路径
        //设置响应的头信息和响应的类型
        resp.setContentType("application/octet-stream");
        resp.addHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(filename,"UTF-8"));

        //跳转页面
        req.getRequestDispatcher(path).forward(req,resp);//跳转一个路径
        //清空缓存区
        resp.flushBuffer();
    }
}