文件上传时，file是一个临时文件，需要转存到指定位置，否则本次请求完成后临时文件就被删除
Controller后台代码：
package com.itheima.reggie.controller;
import com.itheima.reggie.common.R;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.UUID;
/**
* 文件上传和下载
*/
@RestController
@RequestMapping("/common")
public class CommonController {
@Value("${reggie.path}")
private String basePath;
@PostMapping("/upload")
public R<String> upload(MultipartFile file) {
// 获取原始的文件名
String filename = file.getOriginalFilename();
// 获取的后缀
String suffix = filename.substring(filename.lastIndexOf("."));
// 通过UUID生成一个文件名防止文件重复后覆盖原文件
filename = UUID.randomUUID().toString() + suffix;
// 创建一个目录对象
File dir = new File(basePath);
// 目录不存在时创建
if (dir.exists()) {
dir.mkdirs();
}
try {
// 将临时文件储存到指定位置
file.transferTo(new File(basePath + filename));
} catch (IOException e) {
e.printStackTrace();
}
// 返回文件名称
return R.success(filename);
}
@GetMapping("/download")
public void download(String name, HttpServletResponse response) {
try {
// 从本地磁盘进行读取
FileInputStream fileInputStream = new FileInputStream(new File(basePath + name));
// 从response中获取输出流对象
ServletOutputStream outputStream = response.getOutputStream();
response.setContentType("image/jpeg");
// 进行读取
int len = 0;
byte[] bytes = new byte[1024];
// 当bytes没有数据的时候 返回-1
while((len = fileInputStream.read(bytes)) != -1) {
outputStream.write(bytes, 0, len);
outputStream.flush();
}
outputStream.close();
fileInputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
前端：（来自黑马）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>文件上传</title>
<!-- 引入样式 -->
<link rel="stylesheet" href="../../plugins/element-ui/index.css" />
<link rel="stylesheet" href="../../styles/common.css" />
<link rel="stylesheet" href="../../styles/page.css" />
</head>
<body>
<div class="addBrand-container" id="food-add-app">
<div class="container">
<el-upload class="avatar-uploader"
action="/common/upload"
:show-file-list="false"
:on-success="handleAvatarSuccess"
:before-upload="beforeUpload"
ref="upload">
<img v-if="imageUrl" :src="imageUrl" class="avatar"></img>
<i v-else class="el-icon-plus avatar-uploader-icon"></i>
</el-upload>
</div>
</div>
<!-- 开发环境版本，包含了有帮助的命令行警告 -->
<script src="../../plugins/vue/vue.js"></script>
<!-- 引入组件库 -->
<script src="../../plugins/element-ui/index.js"></script>
<!-- 引入axios -->
<script src="../../plugins/axios/axios.min.js"></script>
<script src="../../js/index.js"></script>
<script>
new Vue({
el: '#food-add-app',
data() {
return {
imageUrl: ''
}
},
methods: {
handleAvatarSuccess (response, file, fileList) {
this.imageUrl = `/common/download?name=${response.data}`
},
beforeUpload (file) {
if(file){
const suffix = file.name.split('.')[1]
const size = file.size / 1024 / 1024 < 2
if(['png','jpeg','jpg'].indexOf(suffix) < 0){
this.$message.error('上传图片只支持 png、jpeg、jpg 格式！')
this.$refs.upload.clearFiles()
return false
}
if(!size){
this.$message.error('上传文件大小不能超过 2MB!')
return false
}
return file
}
}
}
})
</script>
</body>
</html>
标签：MybatisPlus,SpringBoot,--,springframework,filename,file,new,import,response From： https://www.cnblogs.com/zhaolei0419/p/16811331.html