对象存储服务(OSS)

在项目中，我们通常需要存储一些非结构化的数据，比如：图片文件，视频文件，音频文件等数据，为了方便的存储这些数据，我们会使用对象存储服务，以用阿里云的对象存储服务为例

对象存储基本概念:

对象: 在MinIO中对象指的是二进制数据，甚至有时指的是Blob(Binary Large OBject)，二进制数据可以是图片，音视频文件，可执行文件等等
桶(bucket): MinIO用桶来组织对象，一个桶类似于操作系统中的一个目录，一个桶中可以存储任意多个对象

开通对象存储服务

首先进入阿里云官网——产品

进入oss页面点击立即开通

点击立即去支付即可

开通免费使用

点击立即使用，开通免费试用

创建bucket

开启公共访问

创建好桶之后，默认桶中的数据不允许直接通过url访问，所以我们需要打开公共访问权限

创建RAM账号

这里说明一下，为了安全起见，我们创建一个RAM子账号，给子账号授权管理OSS权限，通过子账号的ACCESS KEY来访问OSS。我们的最终目的是获取RAM账号的AceessKeyId和AccessKey Secret

最终在这里获取到AccessKeyId和AccessKey Secret

Java快速入门 (aliyun.com)

给RAM账号授权OSS操作权限

引入依赖

<!-- https://mvnrepository.com/artifact/com.aliyun.oss/aliyun-sdk-oss -->
<dependency>
    <groupId>com.aliyun.oss</groupId>
    <artifactId>aliyun-sdk-oss</artifactId>
    <version>3.15.2</version>
</dependency>

使用demo

这里阿里云产品文档中Java代码实现的demo

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import java.io.ByteArrayInputStream;

public class OssDemo {

  public static void main(String[] args) throws Exception {
    // Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。
    String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
    // 阿里云账号AccessKey拥有所有API的访问权限，风险很高。强烈建议您创建并使用RAM用户进行API访问或日常运维，请登录RAM控制台创建RAM用户。
    String accessKeyId = "yourAccessKeyId";
    String accessKeySecret = "yourAccessKeySecret";
    // 填写Bucket名称，例如examplebucket。
    String bucketName = "examplebucket";
    // 填写Object完整路径，例如exampledir/exampleobject.txt。Object完整路径中不能包含Bucket名称。
    String objectName = "exampledir/exampleobject.txt";

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

    try {
      String content = "Hello OSS";
      ossClient.putObject(bucketName, objectName, new ByteArrayInputStream(content.getBytes()));
    } 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();
      }
    }
  }
}

在创建Bucket的时候，我们指定了bucket名称，选择了服务器所在地域(所在地域决定了endpoint)

其中有这样的几项信息

# 武汉地域对应的endpoint
endpoint=oss-cn-wuhan-lr.aliyuncs.com
bucket=你自己定义的名称
# 另外要访问OSS还需要AccessKey和AccessSecret，这个请保管好，不要泄露出去
accessKey=你自己的accessKey
accessSecret=你自己的accessSecret

接着我们利用这些值，上传一下本地文件

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.PutObjectResult;

import java.io.File;
import java.io.FileInputStream;
import java.util.UUID;

public class Demo {

  public static void main(String[] args) throws Exception {
    // Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。
    String endpoint = "oss-cn-beijing.aliyuncs.com";
    // 阿里云账号AccessKey拥有所有API的访问权限，风险很高。强烈建议您创建并使用RAM用户进行API访问或日常运维，请登录RAM控制台创建RAM用户。
    String accessKeyId = "LTAI5tPomn5sTKq2kgBxFDz1";
    String accessKeySecret = "RPQtyACBzSRmcAVZ58K3hWh1Q5l5mY";
    // 填写Bucket名称，例如examplebucket。
    String bucketName = "cskaoyan-word";

    String path = "d:/tmp";
    String fileName = "ikun.jpeg";

    // 填写Object完整路径，例如exampledir/exampleobject.txt。Object完整路径中不能包含Bucket名称。
    String suffix = fileName.substring(fileName.lastIndexOf("."));//ikun.jpeg suffix=.jpeg
    String objectName = UUID.randomUUID().toString() + suffix;

    // 创建OSSClient实例。
    OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);
    FileInputStream inputStream = null;
    try {
      inputStream = new FileInputStream(new File(path, fileName));
      // 保存在哪个bucket、保存的文件名、输入流
      PutObjectResult putObjectResult = ossClient.putObject(bucketName, objectName, inputStream);
    } 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();
      }
      if (inputStream != null) {
        inputStream.close();
      }
    }
  }
}

那么我们后面方便使用可以封装为方法

封装

上传file，我们使用SpringMVC的Handler接收为MultipartFile，然后获得inputStream来完成上传，该方法的返回值为上传结果访问的URL，除了可以向OSS的桶中存放文件完成文件上传外，我们还可以删除OSS的桶中的文件

@Service
@Slf4j
public class OssServiceImpl implements OssService{
 
    /**
     * 文件上传
     */
    @Override
    public String upload(MultipartFile file) throws IOException {
        
        String endpoint = "oss-cn-beijing.aliyuncs.com";
        String accessKeyId = "LTAI5t8gpxPTCR6W58RnZq4u";
        String accessKeySecret = "mVPbpbxia0JQotb7HyJAREV8QUuq8h";
        String bucketName = "wdproject2";
        
        // 构造桶中的对象名称
        String originalFilename = file.getOriginalFilename();
        String extension = originalFilename.substring(originalFilename.lastIndexOf("."));
        String objectName = UUID.randomUUID() + extension;

        String region = "beijing";
        // 创建 OSSClient 实例
        OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);
 

        try {
            // 向桶中放入指定名称的对象
            ossClient.putObject(aliOssProperties.getBucketName(), objectName, file.getInputStream());

            //文件访问路径规则 https://BucketName.Endpoint/ObjectName
            StringBuilder stringBuilder = new StringBuilder("https://");
            stringBuilder.append(aliOssProperties.getBucketName())
                    .append(".")
                    .append(aliOssProperties.getEndpoint())
                    .append("/")
                    .append(objectName);
        } catch (OSSException oe) {
            log.error("阿里OSS异常，Error Message:{}", oe.getErrorMessage());
        } catch (ClientException ce) {
            log.error("阿里OSS Client异常，Error Message:{}", ce.getMessage());
        } finally {
            if (!ObjectUtils.isEmpty(ossClient)) {
                ossClient.shutdown();
            }
        }

        // 返回访问文件的url
        return stringBuilder.toString();
    }

    @Override
    public void deleteFile(String objectName)  {
        String endpoint = "oss-cn-beijing.aliyuncs.com";
        String accessKeyId = "LTAI5t8gpxPTCR6W58RnZq4u";
        String accessKeySecret = "mVPbpbxia0JQotb7HyJAREV8QUuq8h";
        String bucketName = "wdproject2";
      

        String region = "beijing";
       // 创建 OSSClient 实例
       OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);
        try {
            // 删除桶中指定对象
            ossClient.deleteObject(bucketName, objectName);
        } catch (OSSException oe) {
            log.error("阿里OSS异常，Error Message:{}", oe.getErrorMessage());
        } catch (ClientException ce) {
            log.error("阿里OSS Client异常，Error Message:{}", ce.getMessage());
        } finally {
            if (!ObjectUtils.isEmpty(ossClient)) {
                ossClient.shutdown();
            }
        }


    }
}