JavaWeb——上传下载学习

准备工作：创建web项目，准备jar包：javaee-api-7.0.jar、smartupload.jar，在web目录下新建upload文件夹。

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    上传者：${uname}<br>
    上传图片：<img src="upload/${filename}"><br>
    <a href="downimg?filename=${filename}">下载</a>
</body>
</html>

UploadServlet.java

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("/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();
            String contentType = file.getContentType();

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

            //5. 指定上传的路径
            String uploadpath = "/upload/"+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);
            req.setAttribute("uname",uname);
            req.getRequestDispatcher("success.jsp").forward(req,resp);
        } catch (SmartUploadException e) {
    
    
            e.printStackTrace();
        }
    }
}

success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    上传者：${uname}<br>
    上传图片：<img src="upload/${filename}"><br>
    <a href="downimg?filename=${filename}">下载</a>

</body>
</html>

DownloadServlet.java

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("/downimg")
public class DownloadServlet 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");
        String path = "/upload/"+filename;
        //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);
        //清空缓存区
        resp.flushBuffer();

    }
}

效果图：
在这里插入图片描述

在这里插入图片描述

JavaWeb——上传下载学习

index.jsp

UploadServlet.java

success.jsp

DownloadServlet.java

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