<template>
  <div class="form-group">
    <el-upload
        action="http://localhost:8081/upload"
        :on-preview="handlePreview"
        accept='.jpg'
        :limit="10"
    >
        <el-button size="small" type="primary">點擊上傳</el-button>
        <div slot="tip" class="el-upload__tip">只能上傳jpg/png文件，且不超過500kb</div>
    </el-upload>
  </div>
</template>

<script>

export default {
    name: "updateImg",
    methods:{
        handlePreview(file){
            window.open(file.response.url);
            console.log(file.response.url);
        }
    }
}
</script>

<style scoped>

</style>

server:
  port: 8081
  
file-save-path: D:\SoftWare\SpringToolSuite\WorkPlace\HelloWorld\src\main\resources\static\images\
spring:
  mvc:
    view:
      prefix: /
      suffix: .jsp

package com.etc.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfig implements WebMvcConfigurer{
	
	@Value("${file-save-path}")
	private String fileSavePath;
	
	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		registry.addResourceHandler("/images/**").addResourceLocations("file:"+fileSavePath);
		//System.out.println("file:"+fileSavePath);
	}

}

package com.etc.controller;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import javax.servlet.http.HttpServletRequest;
import javax.sound.midi.SysexMessage;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

@CrossOrigin
@RestController
public class ImgUploadController {

	SimpleDateFormat sdf = new SimpleDateFormat("/yyyy.MM.dd/");
	
	@Value("${file-save-path}")
	private String fileSavePath;
	
	@PostMapping("/upload")
	public Map<String, Object> fileupload(MultipartFile file,HttpServletRequest req){
		
		Map<String,Object> result = new HashMap<>();
		//獲取文件的名字
		String originName = file.getOriginalFilename();
		System.out.println("originName:"+originName);
		//判斷文件類型
		if(!originName.endsWith(".jpg")) {
			result.put("status","error");
			result.put("msg", "文件類型不對");
			return result;
		}
		//給上傳的文件新建目錄
		String format = sdf.format(new Date());
		String realPath = fileSavePath + format;
		System.out.println("realPath:"+realPath);
		//若目錄不存在則創(chuàng)建目錄
		File folder = new File(realPath);
		if(! folder.exists()) {
			folder.mkdirs();
		}
		//給上傳文件取新的名字，避免重名
		String newName = UUID.randomUUID().toString() + ".jpg";
		try {
			//生成文件，folder為文件目錄，newName為文件名
			file.transferTo(new File(folder,newName));
			//生成返回給前端的url
			String url = req.getScheme() + "://" + req.getServerName() + ":" + req.getServerPort() +"/images"+ format + newName;
			System.out.println("url:"+url);
			//返回URL
			result.put("status", "success");
			result.put("url", url);
 		}catch (IOException e) {
			// TODO Auto-generated catch block
 			result.put("status", "error");
 			result.put("msg",e.getMessage());
		}
		return result;
				
	}
}