第一步：

package com.sky.properties;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "sky.alioss")
@Data
public class AliOssProperties {

    private String endpoint;
    private String accessKeyId;
    private String accessKeySecret;
    private String bucketName;

}

package com.sky.utils;

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import java.io.ByteArrayInputStream;

@Data
@AllArgsConstructor
@Slf4j
public class AliOssUtil {

    private String endpoint;
    private String accessKeyId;
    private String accessKeySecret;
    private String bucketName;

    /**
     * 文件上传
     *
     * @param bytes
     * @param objectName
     * @return
     */
    public String upload(byte[] bytes, String objectName) {

        // 创建OSSClient实例。
        OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);

        try {
            // 创建PutObject请求。
            ossClient.putObject(bucketName, objectName, new ByteArrayInputStream(bytes));
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }

        //文件访问路径规则 https://BucketName.Endpoint/ObjectName
        StringBuilder stringBuilder = new StringBuilder("https://");
        stringBuilder
                .append(bucketName)
                .append(".")
                .append(endpoint)
                .append("/")
                .append(objectName);

        log.info("文件上传到:{}", stringBuilder.toString());

        return stringBuilder.toString();
    }
}

第二步：

阿里云OSS官网注册 ：

在网站里找到以下四个参数：

 但是，这个在创建后要自己保存，后面如果忘了就查不到了。

第三步：

package com.sky.config;

import com.sky.properties.AliOssProperties;
import com.sky.utils.AliOssUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 配置类，用于创建AliOssUtil对象
 */
@Configuration
@Slf4j
public class OssConfiguration {

    @Bean
    @ConditionalOnMissingBean
    public AliOssUtil aliOssUtil(AliOssProperties aliOssProperties){
        log.info("开始创建阿里云文件上传工具类对象：{}",aliOssProperties);
        return new AliOssUtil(aliOssProperties.getEndpoint(), aliOssProperties.getAccessKeyId(), aliOssProperties.getAccessKeySecret(), aliOssProperties.getBucketName());

    }
}

第四步：

application.yml文件：

application-dev.yml文件： 

第五步（正式开始写文件上传接口）：

package com.sky.controller.admin;


import com.sky.constant.MessageConstant;
import com.sky.result.Result;
import com.sky.utils.AliOssUtil;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
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 java.io.IOException;
import java.util.UUID;

/**
 * 通用接口
 */
@RestController
@RequestMapping("/admin/common")
@Api(tags = "通用接口")
@Slf4j
public class CommonController {

    @Autowired
    private AliOssUtil aliOssUtil;
    @PostMapping("/upload")
    @ApiOperation("文件上传")
    public Result<String> upload(MultipartFile file){
        log.info("文件上传:{}",file);
        try {
            //原始文件名
            String originalFilename = file.getOriginalFilename();
            //截取原始文件名的后缀
            String extension = originalFilename.substring(originalFilename.lastIndexOf("."));
            //构造新文件名称
            String objectName = UUID.randomUUID().toString() + extension;

            //文件的请求路径
            String filePath = aliOssUtil.upload(file.getBytes(), objectName);
            return Result.success(filePath);
        } catch (IOException e) {
            log.error("文件上传失败：{}",e);
        }
        return Result.error(MessageConstant.UPLOAD_FAILED);
    }

}