数据安全性-String-上传-import-对象存储 OSS-阿里云

OSS提供基于MD5和CRC64的数据校验，确保上传、下载和拷贝文件（Object）过程中的数据完整性。

MD5校验

如果上传文件时设置了Content-MD5，OSS会根据接收的内容计算MD5。OSS计算的MD5值和上传提供的MD5值不一致时，则返回InvalidDigest异常，从而保证数据的完整性。返回InvalidDigest异常后，您需要重新上传文件。

以下代码用于上传文件时进行MD5校验：

import com.aliyun.oss.*;
import com.aliyun.oss.common.utils.BinaryUtil;
import com.aliyun.oss.model.ObjectMetadata;
import java.io.ByteArrayInputStream;

public class Demo {
    public static void main(String[] args) throws Throwable {
        // 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的完整路径。Object完整路径中不能包含Bucket名称。
        String objectName = "exampledir/object";

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

        try {
            // 上传字符串。
            String content = "Hello OSS";

            ObjectMetadata meta = new ObjectMetadata();
            // 设置MD5校验。
            String md5 = BinaryUtil.toBase64String(BinaryUtil.calculateMd5(content.getBytes()));
            meta.setContentMD5(md5);

            ossClient.putObject(bucketName, objectName, new ByteArrayInputStream(content.getBytes()), meta);

        } 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();
            }
        }
    }
}

说明 putObject、getObject、appendObject、postObject、uploadPart支持MD5校验。

CRC64校验

上传、下载和拷贝文件时默认开启CRC数据校验，确保数据的完整性。

说明

putObject、getObject、appendObject、uploadPart支持CRC64校验。上传时默认开启CRC校验，如果客户端计算的CRC值与服务端返回的CRC值不一致，则会抛出InconsistentException异常。
范围下载不支持CRC64校验。
CRC64校验会占用一定的CPU，对上传、下载速度均会有影响。

下载文件时CRC64校验

以下代码用于下载文件时进行CRC64数据完整性校验：

import com.aliyun.oss.*;
import com.aliyun.oss.common.utils.IOUtils;
import com.aliyun.oss.internal.OSSHeaders;
import com.aliyun.oss.internal.OSSUtils;
import com.aliyun.oss.model.GetObjectRequest;
import com.aliyun.oss.model.OSSObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Demo {
    public static void main(String[] args) throws Throwable {
        // 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的完整路径。Object完整路径中不能包含Bucket名称。
        String objectName = "exampledir/object";

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

        try {
            // 流式下载。
            GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, objectName);
            OSSObject ossObject = ossClient.getObject(bucketName, objectName);

            // 读取文件内容，只有读取文件内容之后才能获取clientCrc。
            System.out.println("Object content:");
            BufferedReader reader = new BufferedReader(new InputStreamReader(ossObject.getObjectContent()));
            while (true) {
                String line = reader.readLine();
                if (line == null) break;

                System.out.println("\n" + line);
            }
            // 数据读取完成后，获取的流必须关闭，否则会造成连接泄漏，导致请求无连接可用，程序无法正常工作。
            reader.close();

            // 查看客户端是否开启了CRC校验，默认是开启状态。
            Boolean isCrcCheckEnabled = ((OSSClient)ossClient).getClientConfiguration().isCrcCheckEnabled();
            // 查看是否是范围下载请求。范围下载方式不支持CRC校验。
            Boolean isRangGetRequest = getObjectRequest.getHeaders().get(OSSHeaders.RANGE) != null;

            // 校验CRC，且只有读取文件内容之后才能获取clientCRC。
            if (isCrcCheckEnabled && !isRangGetRequest) {
                Long clientCRC = IOUtils.getCRCValue(ossObject.getObjectContent());
                OSSUtils.checkChecksum(clientCRC, ossObject.getServerCRC(), ossObject.getRequestId());
            }
        } 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();
            }
        }
    }
}

追加上传时CRC64校验

以下代码用于追加上传时进行CRC64数据完整性校验：

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.*;
import java.io.ByteArrayInputStream;

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 = "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exampleobject.txt。Object完整路径中不能包含Bucket名称。
        String objectName = "exampleobject.txt";
        // 填写第一次追加内容，例如Hello。
        String firstAppendContent = "Hello";
        // 填写第二次追加内容，例如World。
        String secondAppendContent = "World";

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

        try {
            // 第一次追加。
            AppendObjectRequest appendObjectRequest = new AppendObjectRequest(bucketName, objectName, new ByteArrayInputStream(firstAppendContent.getBytes()));
            appendObjectRequest.setPosition(0L);
            // 初始化CRC。初始化CRC之后，SDK内部默认会对上传结果进行CRC校验。
            appendObjectRequest.setInitCRC(0L);
            AppendObjectResult appendObjectResult = ossClient.appendObject(appendObjectRequest);

            // 第二次追加。
            appendObjectRequest = new AppendObjectRequest(bucketName, objectName, new ByteArrayInputStream(secondAppendContent.getBytes()));
            appendObjectRequest.setPosition(appendObjectResult.getNextPosition());
            // 初始化CRC设置为已上传数据的CRC。初始化CRC之后，SDK内部默认会对上传结果进行CRC校验。
            appendObjectRequest.setInitCRC(appendObjectResult.getClientCRC());
            ossClient.appendObject(appendObjectRequest);
        } 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();
            }
        }
    }
}

MD5校验

CRC64校验

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