【前后端的那些事】15min快速实现图片上传，预览功能(ElementPlus+Springboot)-编程知识

文章目录

- Element Plus + SpringBoot实现图片上传，预览，删除
- - - 效果展示
  - 1. 后端代码
  - - 1.1 controller
    - 1.2 service
  - 2. 前端代码
  - - 2.1 路由创建
    - 2.2 api接口
    - 2.2 文件创建
  - 3. 前端上传组件封装

前言：最近写项目，发现了一些很有意思的功能，想写文章，录视频把这些内容记录下。但这些功能太零碎，如果为每个功能都单独搭建一个项目，这明显不合适。于是我想，就搭建一个项目，把那些我想将的小功能全部整合到一起。实现 搭一次环境，处处使用。

本文主要实现以下功能

图片上传

环境搭建
文章链接

已录制视频
视频链接

仓库地址
https://github.com/xuhuafeifei/fgbg-font-and-back.git

Element Plus + SpringBoot实现图片上传，预览，删除

效果展示

提交样式
放大预览

在这里插入图片描述

成功提交后端
访问url

在这里插入图片描述

后端存储
根据url下载/访问图片

在这里插入图片描述

1. 后端代码

1.1 controller

import com.fgbg.common.utils.R;
import com.fgbg.demo.service.FileService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.UUID;@RestController
@RequestMapping("/common/file")
public class FileController {@Autowired@Qualifier("localFileService")private FileService fileService;/*** 上传接口*/@RequestMapping("/upload")public R upload(@RequestParam("image") MultipartFile file) throws IOException {String url = fileService.uploadFile(file, UUID.randomUUID().toString().substring(0, 10)+ "-" + file.getOriginalFilename());return R.ok().put("data", url);}/*** 下载接口*/@RequestMapping("/download/{fileName}")public void download(@PathVariable("fileName") String fileName, HttpServletRequest request, HttpServletResponse response) {fileService.downloadFile(fileName, request, response);}/*** 删除接口*/@RequestMapping("/delete")public R deleteFile(@RequestParam String fileName) {boolean flag = fileService.deleteFile(fileName);return R.ok().put("data", flag);}
}

1.2 service

tip: 文件上传存储有多种解决方案，比如minio，阿里云…

笔者考虑到编写容易程度与文章核心解决问题，采用了最原始的存储方法，即本地存储。以后端所在服务器为存储容器，将前端上传的图片以FileIO的形式进行存储。

考虑到有多种存储方式，读者可以实现FileService接口，自行编写impl类，以达到不同的文件存储的具体实现方式

import org.springframework.web.multipart.MultipartFile;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;public interface FileService {/*** 上传图片, 返回url*/String uploadFile(MultipartFile file, String fileName) throws IOException;/*** 下载图片*/void downloadFile(String fileName, HttpServletRequest request, HttpServletResponse response);/*** 删除图片*/boolean deleteFile(String fileName);
}

impl

import com.fgbg.demo.service.FileService;
import org.apache.commons.io.FileUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Paths;/*** 基于本地的文件管理服务*/
@Service("localFileService")
public class LocalFileServiceImpl implements FileService {/*** 文件访问域名(请求下载的接口)*/private static final String DOMAIN = "http://localhost:9005/api_demo/common/file/download/";/*** 文件物理存储位置*/private static final String STORE_DIR = "E:\\B站视频创作\\前后端项目构建-小功能实现\\代码\\backend\\src\\main\\resources\\pict\\";/*** 上传图片, 返回url** @param file* @param fileName*/@Overridepublic String uploadFile(MultipartFile file, String fileName) throws IOException {// 获取文件流InputStream is = file.getInputStream();// 在服务器中存储文件FileUtils.copyInputStreamToFile(is, new File(STORE_DIR + fileName));// 返回图片urlString url = DOMAIN + fileName;System.out.println("文件url: " + url);return url;}/*** 下载图片** @param fileName*/@Overridepublic void downloadFile(String fileName, HttpServletRequest request, HttpServletResponse response) {// 获取真实的文件路径String filePath = STORE_DIR + fileName;System.out.println("++++完整路径为："+filePath);try {// 下载文件// 设置响应头response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + fileName);// 读取文件内容并写入输出流Files.copy(Paths.get(filePath), response.getOutputStream());response.getOutputStream().flush();} catch (IOException e) {response.setStatus(404);}}/*** 删除图片** @param fileName*/@Overridepublic boolean deleteFile(String fileName) {// 获取真实的文件路径String filePath = STORE_DIR + fileName;System.out.println("++++完整路径为："+filePath);File file = new File(filePath);return file.delete();}
}

2. 前端代码

2.1 路由创建

/src/router/modules/file.ts

const { VITE_HIDE_HOME } = import.meta.env;
const Layout = () => import("@/layout/index.vue");export default {path: "/file",name: "file",component: Layout,redirect: "/pict",meta: {icon: "homeFilled",title: "文件",rank: 0},children: [{path: "/pict",name: "pict",component: () => import("@/views/file/pict.vue"),meta: {title: "图片",showLink: VITE_HIDE_HOME === "true" ? false : true}}]
} as RouteConfigsTable;

2.2 api接口

tip:

文件上传只能用post
前端部分图片封装为FormData对象
请求头标明"Content-Type": "multipart/form-data"

import { http } from "@/utils/http";
import { R, baseUrlApi } from "./utils";/** upload batch */
export const uploadBatch = (data: FormData) => {return http.request<R<any>>("post", baseUrlApi("common/file/uploadList"), {data,headers: {"Content-Type": "multipart/form-data"}});
};/** upload */
export const upload = (data: FormData) => {return http.request<R<any>>("post", baseUrlApi("common/file/upload"), {data,headers: {"Content-Type": "multipart/form-data"}});
};

2.2 文件创建

/src/views/file/pict.vue

tip:

图片封装为FormData

formdata添加图片信息时，使用的是append()方法. append(name: string, value: string | Blob)

append的第一个参数，对应的是后端@RequestParam("xxx") MultipartFile file中xxx的值，本文中后端批量上传接口，xxx值为’imageList’

Element Plus上传图片，图片数据中都会有一个新的字段数据raw，这个数据我们就理解成文件本身。像后端提交数据提交的也是raw本身，而非其余额外数据

append第二个参数，提交的是fileList中每个文件元素的raw属性s数据

<template><el-uploadv-model:file-list="fileList"list-type="picture-card"multiple:auto-upload="false":on-preview="handlePictureCardPreview":on-remove="handleRemove"><el-icon><Plus /></el-icon></el-upload><el-dialog v-model="dialogVisible"><img w-full :src="dialogImageUrl" alt="Preview Image" /></el-dialog><el-button @click="submit">提交</el-button>
</template><script lang="ts" setup>
import { ref } from "vue";
import { Plus } from "@element-plus/icons-vue";
import { uploadBatch } from "/src/api/file.ts";
import type { UploadProps } from "element-plus";
import { ElMessage } from "element-plus";const submit = () => {console.log(fileList.value);// 封装formDataconst data = new FormData();// forEach遍历的时fileList.value, 所有element不需要.value去除代理fileList.value.forEach(element => {data.append("imageList", element.raw);});uploadBatch(data).then(res => {console.log(res);if (res.code === 0) {ElMessage.success("上传成功");} else {ElMessage.error("上传失败: " + res.msg);}});
};const fileList = ref();const dialogImageUrl = ref("");
const dialogVisible = ref(false);const handleRemove: UploadProps["onRemove"] = (uploadFile, uploadFiles) => {console.log(uploadFile, uploadFiles);
};const handlePictureCardPreview: UploadProps["onPreview"] = uploadFile => {dialogImageUrl.value = uploadFile.url!;dialogVisible.value = true;
};
</script>

3. 前端上传组件封装

如果没有组件封装需求，那就不需要修改代码。
组件封装视频链接

tip: 提交逻辑交由父组件实现

child.vue

<template><el-uploadv-model:file-list="localFileList"list-type="picture-card"multiple:auto-upload="false":on-preview="handlePictureCardPreview":on-remove="handleRemove"><el-icon><Plus /></el-icon></el-upload><el-dialog v-model="dialogVisible"><img w-full :src="dialogImageUrl" alt="Preview Image" /></el-dialog>
</template><script lang="ts" setup>
import { ref, watch } from "vue";
import { Plus } from "@element-plus/icons-vue";
import type { UploadProps } from "element-plus";// 定义数据
const props = defineProps({fileList: {type: Array,default: () => []}
});// 将父组件的数据拆解为子组件数据
const localFileList = ref(props.fileList);// 监听localFileList, 跟新父组件数据
watch(localFileList,newValue => {emits("update:fileList", newValue);},{deep: true}
);// 定义组件事件, 跟新fileList
const emits = defineEmits(["update:fileList"]);const dialogImageUrl = ref("");
const dialogVisible = ref(false);const handleRemove: UploadProps["onRemove"] = (uploadFile, uploadFiles) => {console.log(uploadFile, uploadFiles);
};const handlePictureCardPreview: UploadProps["onPreview"] = uploadFile => {dialogImageUrl.value = uploadFile.url!;dialogVisible.value = true;
};
</script>

父组件

<script setup lang="ts">
import Child from "./component/child.vue";
import { ref } from "vue";
import { ElMessage } from "element-plus";
import { uploadBatch } from "/src/api/file.ts";const fileList = ref();const submit = () => {console.log(fileList.value);// 封装formDataconst data = new FormData();// forEach遍历的时fileList.value, 所有element不需要.value去除代理fileList.value.forEach(element => {data.append("imageList", element.raw);});uploadBatch(data).then(res => {console.log(res);if (res.code === 0) {ElMessage.success("上传成功");} else {ElMessage.error("上传失败: " + res.msg);}});
};
</script><template><Child v-model:fileList="fileList" /><el-button @click="submit">提交</el-button>
</template><style lang="scss" scoped></style>