对象存储 OSS：POST V4签名

使用AK、SK计算签名

import com.aliyun.oss.common.utils.BinaryUtil;
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class Demo {
    public static void main(String[] args) throws Exception {
        // 运行本代码示例之前，请确保已设置环境变量OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        String accesskeyid =  System.getenv().get("OSS_ACCESS_KEY_ID");
        String accesskeysecret =  System.getenv().get("OSS_ACCESS_KEY_SECRET");

        // 步骤1：创建policy。
        ObjectMapper mapper = new ObjectMapper();

        Map<String, Object> policy = new HashMap<>();
        policy.put("expiration", "2024-12-03T13:00:00.000Z");

        List<Object> conditions = new ArrayList<>();

        Map<String, String> bucketCondition = new HashMap<>();
        bucketCondition.put("bucket", "examplebucket");
        conditions.add(bucketCondition);

        Map<String, String> signatureVersionCondition = new HashMap<>();
        signatureVersionCondition.put("x-oss-signature-version", "OSS4-HMAC-SHA256");
        conditions.add(signatureVersionCondition);

        Map<String, String> credentialCondition = new HashMap<>();
        credentialCondition.put("x-oss-credential", "accesskeyid/20241203/cn-hangzhou/oss/aliyun_v4_request"); // 替换为实际的 access key id
        conditions.add(credentialCondition);

        Map<String, String> dateCondition = new HashMap<>();
        dateCondition.put("x-oss-date", "20241203T121212Z");
        conditions.add(dateCondition);

        conditions.add(Arrays.asList("content-length-range", 1, 10));
        conditions.add(Arrays.asList("eq", "$success_action_status", "201"));
        conditions.add(Arrays.asList("starts-with", "$key", "user/eric/"));
        conditions.add(Arrays.asList("in", "$content-type", Arrays.asList("image/jpg", "image/png")));
        conditions.add(Arrays.asList("not-in", "$cache-control", Arrays.asList("no-cache")));

        policy.put("conditions", conditions);

        String jsonPolicy = mapper.writeValueAsString(policy);
        // 步骤2：构造待签名字符串（StringToSign）。
        String stringToSign = new String(Base64.encodeBase64(jsonPolicy.getBytes()));

        // 步骤3：计算SigningKey。
        byte[] dateKey = hmacsha256(("aliyun_v4" + accesskeysecret).getBytes(), "20231203");
        byte[] dateRegionKey = hmacsha256(dateKey, "cn-hangzhou");
        byte[] dateRegionServiceKey = hmacsha256(dateRegionKey, "oss");
        byte[] signingKey = hmacsha256(dateRegionServiceKey, "aliyun_v4_request");

        // 步骤4：计算Signature。
        byte[] result = hmacsha256(signingKey, stringToSign);
        String signature = BinaryUtil.toHex(result);
        System.out.println("signature:" + signature);

    }

    public static byte[] hmacsha256(byte[] key, String data) {
        try {
            // 初始化HMAC密钥规格，指定算法为HMAC-SHA256并使用提供的密钥。
            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "HmacSHA256");

            // 获取Mac实例，并通过getInstance方法指定使用HMAC-SHA256算法。
            Mac mac = Mac.getInstance("HmacSHA256");
            // 使用密钥初始化Mac对象。
            mac.init(secretKeySpec);

            // 执行HMAC计算，通过doFinal方法接收需要计算的数据并返回计算结果的数组。
            byte[] hmacBytes = mac.doFinal(data.getBytes());

            return hmacBytes;
        } catch (Exception e) {
            throw new RuntimeException("Failed to calculate HMAC-SHA256", e);
        }
    }
}

返回结果如下：

signature:3908473f7dbfb79a102eaaa44ca1edec8d7058ce3bd1c624d59eb437463bd5d6

使用临时访问凭证计算签名

使用临时访问凭证STS构造POST签名时，还需要通过调用STS服务的AssumeRole接口获取安全令牌。

import com.aliyun.oss.common.utils.BinaryUtil;
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import com.aliyun.sts20150401.models.AssumeRoleResponse;
import com.aliyun.sts20150401.models.AssumeRoleResponseBody;
import com.aliyun.tea.TeaException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.*;
public class Demo {

    //初始化STS Client
    public static com.aliyun.sts20150401.Client createStsClient() throws Exception {
        com.aliyun.teaopenapi.models.Config config = new com.aliyun.teaopenapi.models.Config()
                // 必填，请确保代码运行环境设置了环境变量 OSS_ACCESS_KEY_ID。
                .setAccessKeyId(System.getenv("OSS_ACCESS_KEY_ID"))
                // 必填，请确保代码运行环境设置了环境变量 OSS_ACCESS_KEY_SECRET。
                .setAccessKeySecret(System.getenv("OSS_ACCESS_KEY_SECRET"));
        // Endpoint 
        config.endpoint = "sts.cn-hangzhou.aliyuncs.com";
        return new com.aliyun.sts20150401.Client(config);
    }

    //获取STS临时凭证
    public static AssumeRoleResponseBody.AssumeRoleResponseBodyCredentials getCredential() throws Exception {
        com.aliyun.sts20150401.Client client = Demo.createStsClient();
        com.aliyun.sts20150401.models.AssumeRoleRequest assumeRoleRequest = new com.aliyun.sts20150401.models.AssumeRoleRequest()
                // 必填，请确保代码运行环境设置了环境变量 OSS_STS_ROLE_ARN。
                .setRoleArn(System.getenv("OSS_STS_ROLE_ARN"))
                .setRoleSessionName("role_session_name");// 自定义会话名称
        com.aliyun.teautil.models.RuntimeOptions runtime = new com.aliyun.teautil.models.RuntimeOptions();
        try {
            // 复制代码运行请自行打印 API 的返回值
            AssumeRoleResponse response = client.assumeRoleWithOptions(assumeRoleRequest, runtime);
            // credentials里包含了后续要用到的AccessKeyId、AccessKeySecret和SecurityToken。
            return response.body.credentials;
        } catch (TeaException error) {
            // 此处仅做打印展示，请谨慎对待异常处理，在工程项目中切勿直接忽略异常。
            // 错误 message
            System.out.println(error.getMessage());
            // 诊断地址
            System.out.println(error.getData().get("Recommend"));
            com.aliyun.teautil.Common.assertAsString(error.message);
        } catch (Exception _error) {
            TeaException error = new TeaException(_error.getMessage(), _error);
            // 此处仅做打印展示，请谨慎对待异常处理，在工程项目中切勿直接忽略异常。
            // 错误 message
            System.out.println(error.getMessage());
            // 诊断地址
            System.out.println(error.getData().get("Recommend"));
            com.aliyun.teautil.Common.assertAsString(error.message);
        }
        return null;
    }

    public static void main(String[] args) throws Exception {

        AssumeRoleResponseBody.AssumeRoleResponseBodyCredentials sts_data = getCredential();
        String accesskeyid = sts_data.accessKeyId;
        String accesskeysecret = sts_data.accessKeySecret;
        String securitytoken = sts_data.securityToken;
        // 步骤1：创建policy。
        ObjectMapper mapper = new ObjectMapper();

        Map<String, Object> policy = new HashMap<>();
        policy.put("expiration", "2024-12-03T13:00:00.000Z");

        List<Object> conditions = new ArrayList<>();

        Map<String, String> bucketCondition = new HashMap<>();
        bucketCondition.put("bucket", "examplebucket");
        conditions.add(bucketCondition);

        Map<String, String> signatureVersionCondition = new HashMap<>();
        signatureVersionCondition.put("x-oss-signature-version", "OSS4-HMAC-SHA256");
        conditions.add(signatureVersionCondition);
        
        Map<String, String> securityTokenCondition = new HashMap<>();
        securityTokenCondition.put("x-oss-security-token", securitytoken);
        conditions.add(securityTokenCondition);
        
        Map<String, String> credentialCondition = new HashMap<>();
        credentialCondition.put("x-oss-credential", "accesskeyid/20241203/cn-hangzhou/oss/aliyun_v4_request"); 
        conditions.add(credentialCondition);

        Map<String, String> dateCondition = new HashMap<>();
        dateCondition.put("x-oss-date", "20241203T121212Z");
        conditions.add(dateCondition);

        conditions.add(Arrays.asList("content-length-range", 1, 10));
        conditions.add(Arrays.asList("eq", "$success_action_status", "201"));
        conditions.add(Arrays.asList("starts-with", "$key", "user/eric/"));
        conditions.add(Arrays.asList("in", "$content-type", Arrays.asList("image/jpg", "image/png")));
        conditions.add(Arrays.asList("not-in", "$cache-control", Arrays.asList("no-cache")));

        policy.put("conditions", conditions);

        String jsonPolicy = mapper.writeValueAsString(policy);
        // 步骤2：构造待签名字符串（StringToSign）。
        String stringToSign = new String(Base64.encodeBase64(jsonPolicy.getBytes()));

        // 步骤3：计算SigningKey。
        byte[] dateKey = hmacsha256(("aliyun_v4" + accesskeysecret).getBytes(), "20231203");
        byte[] dateRegionKey = hmacsha256(dateKey, "cn-hangzhou");
        byte[] dateRegionServiceKey = hmacsha256(dateRegionKey, "oss");
        byte[] signingKey = hmacsha256(dateRegionServiceKey, "aliyun_v4_request");

        // 步骤4：计算Signature。
        byte[] result = hmacsha256(signingKey, stringToSign);
        String signature = BinaryUtil.toHex(result);
        System.out.println("signature:" + signature);

    }

    public static byte[] hmacsha256(byte[] key, String data) {
        try {
            // 初始化HMAC密钥规格，指定算法为HMAC-SHA256并使用提供的密钥。
            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "HmacSHA256");

            // 获取Mac实例，并通过getInstance方法指定使用HMAC-SHA256算法。
            Mac mac = Mac.getInstance("HmacSHA256");
            // 使用密钥初始化Mac对象。
            mac.init(secretKeySpec);

            // 执行HMAC计算，通过doFinal方法接收需要计算的数据并返回计算结果的数组。
            byte[] hmacBytes = mac.doFinal(data.getBytes());

            return hmacBytes;
        } catch (Exception e) {
            throw new RuntimeException("Failed to calculate HMAC-SHA256", e);
        }
    }
}

返回结果如下：

signature:1e09438f7ad01af6b3e144b42c98929c68f8d090ce07f4c277b18d8b62d0aa02