Servlet实现文件上传功能最全最详细代码(支持多文件)

upload.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Titletitle>
    
    >">
    <style type="text/css">
        input[type="submit"] {
            outline: none;
            border-radius: 5px;
            cursor: pointer;
            background-color: #31B0D5;
            border: none;
            width: 70px;
            height: 35px;
            font-size: 20px;
        }

        img {
            border-radius: 50%;
        }

        form {
            position: relative;
            width: 200px;
            height: 200px;
        }

        input[type="file"] {
            position: absolute;
            left: 0;
            top: 0;
            height: 200px;
            opacity: 0;
            cursor: pointer;
        }
    style>

    <script type="text/javascript">
        function prev(event) {
            //获取展示图片的区域
            var img = document.getElementById("prevView");
            //获取文件对象
            var file = event.files[0];
            //获取文件阅读器: Js的一个类,直接使用即可
            var reader = new FileReader();
            reader.readAsDataURL(file);
            reader.onload = function () {
                //给img的src设置图片url
                img.setAttribute("src", this.result);
            }
        }
    script>

head>
<body>


<form action="fileUploadServlet" method="post" enctype="multipart/form-data">
    上传的图片或文件: <img src="2.jpg" alt="" width="200" height="200" id="prevView">
    <input type="file" name="pic" id="" value="" onchange="prev(this)" multiple/>

    输入文件名称: <input type="text" name="name"><br/>

    <input type="submit" value="上传"/>
form>
body>
html>

FileUploadServlet

package com.sparrow.servlet;

import com.sparrow.utils.WebUtils;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.UUID;

/**
 * @Author: 诉衷情の麻雀
 * @Description: TODO
 * @DateTime: 2023/7/15 8:21
 **/
public class FileUploadServlet 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 {
        System.out.println("FileUploadServlet被调用了");
        //1,判断是不是文件表单(enctype="multipart/form-data")
        if (ServletFileUpload.isMultipartContent(req)) {
            //2.创建DiskFileItemFactory对象,用于构建一个解析上传数据的工具对象
            DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();
            //3. 创建一个解析上传数据的工具对象
            ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);
            //解决接收到文件名是中文乱码问题
            servletFileUpload.setHeaderEncoding("utf-8");
            //4. 关键是servletFileUpload对象可以把表单提交的数据text/文件
            //将其封装到FileItem文件项中
            try {
                List<FileItem> list = servletFileUpload.parseRequest(req);
                //System.out.println("list==>" + list);
                for (FileItem fileItem : list) {
                    //System.out.println("fileItem =" + fileItem);
                    if (fileItem.isFormField()) { //如果为真就是文本input text
                        String name = fileItem.getString("utf-8");
                        System.out.println("家具名: " + name);
                    }else { //是一个文件
                        upload(req,fileItem);
                        //5.提示信息
                        resp.setContentType("text/html;charset=utf-8");
                        resp.getWriter().write("上传成功");

                    }
                }
            } catch (Exception e) {
                throw new RuntimeException(e);
            }

        }else {
            System.out.println("不是文件表单...");
        }

    }


    /**
     * 上传文件
     */

    public void upload(HttpServletRequest request,FileItem fileItem) throws Exception {
        String name = fileItem.getName();
        System.out.println("上传的文件名=" + name);
        //1.把这个上传到服务器的temp下的文件保存到指定的目录
        String filePath = "/upload/";
        //2.获取完整目录
        String realPath = request.getServletContext().getRealPath(filePath);
        //3. 创建这个上传的目录=>创建目录
        File fileDirectory = new File(realPath + WebUtils.getYearMonthDay());
        if (!fileDirectory.exists()) { //不存在就创建
            fileDirectory.mkdirs(); //创建
        }

        //4.将文件拷贝到fileDirectory
        // 构建一个上传文件的完整路径: 目录+文件名
        // 对上传的文件名进行处理,前面增加一个前缀,保证是唯一即可
        name = UUID.randomUUID().toString()+"_" + System.currentTimeMillis() +"_"+ name;
        fileItem.write(new File(fileDirectory +"/" + name));
    }
}

工具类WebUtils

public class WebUtils {
    public static String getYearMonthDay() {
        //如何得到当前的日期
        LocalDateTime localDateTime = LocalDateTime.now();
        int year = localDateTime.getYear();
        int monthValue = localDateTime.getMonthValue();
        int dayOfMonth = localDateTime.getDayOfMonth();
        String yearMonthDay = year + "/" + monthValue + "/" + dayOfMonth + "/";
        return yearMonthDay;
    }

}

web.xml


<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>FileUploadServletservlet-name>
        <servlet-class>com.sparrow.servlet.FileUploadServletservlet-class>
    servlet>
    <servlet-mapping>
        <servlet-name>FileUploadServletservlet-name>
        <url-pattern>/fileUploadServleturl-pattern>
    servlet-mapping>
    <servlet>
        <servlet-name>FileDownLoadServletservlet-name>
        <servlet-class>com.sparrow.servlet.FileDownLoadServletservlet-class>
    servlet>
    <servlet-mapping>
        <servlet-name>FileDownLoadServletservlet-name>
        <url-pattern>/fileDownLoadServleturl-pattern>
    servlet-mapping>

项目目录结构

Servlet实现文件上传功能最全最详细代码(支持多文件)_第1张图片

所需要的Jar包

Servlet实现文件上传功能最全最详细代码(支持多文件)_第2张图片

项目演示

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