本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 使用儲存貯體政策管理對 Amazon S3 儲存貯體的存取
<a name="examples-s3-bucket-policies"></a>

您可以設定、取得或刪除儲存*貯體政策*，以管理對 Amazon S3 儲存貯體的存取。

## 先決條件
<a name="codeExamplePrereq"></a>

開始之前，建議您先閱讀[開始使用 適用於 C\+\+ 的 AWS SDK](getting-started.md)。

下載範例程式碼並建置解決方案，如中所述[程式碼範例入門](getting-started-code-examples.md)。

若要執行範例，您的程式碼用來提出請求的使用者描述檔必須具有 AWS （針對 服務和 動作） 的適當許可。如需詳細資訊，請參閱[提供 AWS 登入](credentials.md)資料。

## 設定儲存貯體政策
<a name="set-s3-bucket-policy"></a>

您可以呼叫 `S3Client`的 `PutBucketPolicy`函數，並在 [PutBucketPolicyRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-s3/html/class_aws_1_1_s3_1_1_model_1_1_put_bucket_policy_request.html) 中提供儲存貯體名稱和政策的 JSON 表示法，來設定特定 S3 儲存貯體的儲存貯體政策。

 **Code** 

```
//! Build a policy JSON string.
/*!
  \param userArn: Aws user Amazon Resource Name (ARN).
      For more information, see https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_identifiers.html#identifiers-arns.
  \param bucketName: Name of a bucket.
  \return String: Policy as JSON string.
*/

Aws::String getPolicyString(const Aws::String &userArn,
                            const Aws::String &bucketName) {
    return
            "{\n"
            "   \"Version\":\"2012-10-17\",\n"
            "   \"Statement\":[\n"
            "       {\n"
            "           \"Sid\": \"1\",\n"
            "           \"Effect\": \"Allow\",\n"
            "           \"Principal\": {\n"
            "               \"AWS\": \""
            + userArn +
            "\"\n""           },\n"
            "           \"Action\": [ \"s3:getObject\" ],\n"
            "           \"Resource\": [ \"arn:aws:s3:::"
            + bucketName +
            "/*\" ]\n"
            "       }\n"
            "   ]\n"
            "}";
}
```

```
bool AwsDoc::S3::putBucketPolicy(const Aws::String &bucketName,
                                 const Aws::String &policyBody,
                                 const Aws::S3::S3ClientConfiguration &clientConfig) {
    Aws::S3::S3Client s3Client(clientConfig);

    std::shared_ptr<Aws::StringStream> request_body =
            Aws::MakeShared<Aws::StringStream>("");
    *request_body << policyBody;

    Aws::S3::Model::PutBucketPolicyRequest request;
    request.SetBucket(bucketName);
    request.SetBody(request_body);

    Aws::S3::Model::PutBucketPolicyOutcome outcome =
            s3Client.PutBucketPolicy(request);

    if (!outcome.IsSuccess()) {
        std::cerr << "Error: putBucketPolicy: "
                  << outcome.GetError().GetMessage() << std::endl;
    } else {
        std::cout << "Set the following policy body for the bucket '" <<
                  bucketName << "':" << std::endl << std::endl;
        std::cout << policyBody << std::endl;
    }

    return outcome.IsSuccess();
}
```

**注意**  
[Aws：：Utils：：Json：：JsonValue](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-core/html/class_aws_1_1_utils_1_1_json_1_1_json_value.html) 公用程式類別可用來協助您建構有效的 JSON 物件以傳遞至 `PutBucketPolicy`。

請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/s3/put_bucket_policy.cpp)。

## 取得儲存貯體政策
<a name="get-s3-bucket-policy"></a>

若要擷取 Amazon S3 儲存貯體的政策，請呼叫 `S3Client`的 `GetBucketPolicy`函數，並在 [GetBucketPolicyRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-s3/html/class_aws_1_1_s3_1_1_model_1_1_get_bucket_policy_request.html) 中傳遞儲存貯體的名稱。

 **Code** 

```
bool AwsDoc::S3::getBucketPolicy(const Aws::String &bucketName,
                                 const Aws::S3::S3ClientConfiguration &clientConfig) {
    Aws::S3::S3Client s3Client(clientConfig);

    Aws::S3::Model::GetBucketPolicyRequest request;
    request.SetBucket(bucketName);

    Aws::S3::Model::GetBucketPolicyOutcome outcome =
            s3Client.GetBucketPolicy(request);

    if (!outcome.IsSuccess()) {
        const Aws::S3::S3Error &err = outcome.GetError();
        std::cerr << "Error: getBucketPolicy: "
                  << err.GetExceptionName() << ": " << err.GetMessage() << std::endl;
    } else {
        Aws::StringStream policy_stream;
        Aws::String line;

        outcome.GetResult().GetPolicy() >> line;
        policy_stream << line;

        std::cout << "Retrieve the policy for bucket '" << bucketName << "':\n\n" <<
                  policy_stream.str() << std::endl;
    }

    return outcome.IsSuccess();
}
```

請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/s3/get_bucket_policy.cpp)。

## 刪除儲存貯體政策
<a name="delete-s3-bucket-policy"></a>

若要刪除儲存貯體政策，請呼叫 `S3Client`的 `DeleteBucketPolicy`函數，在 [DeleteBucketPolicyRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-s3/html/class_aws_1_1_s3_1_1_model_1_1_delete_bucket_policy_request.html) 中提供儲存貯體名稱。

 **Code** 

```
bool AwsDoc::S3::deleteBucketPolicy(const Aws::String &bucketName,
                                    const Aws::S3::S3ClientConfiguration &clientConfig) {
    Aws::S3::S3Client client(clientConfig);

    Aws::S3::Model::DeleteBucketPolicyRequest request;
    request.SetBucket(bucketName);

    Aws::S3::Model::DeleteBucketPolicyOutcome outcome = client.DeleteBucketPolicy(request);

    if (!outcome.IsSuccess()) {
        const Aws::S3::S3Error &err = outcome.GetError();
        std::cerr << "Error: deleteBucketPolicy: " <<
                  err.GetExceptionName() << ": " << err.GetMessage() << std::endl;
    } else {
        std::cout << "Policy was deleted from the bucket." << std::endl;
    }

    return outcome.IsSuccess();
}
```

即使儲存貯體還沒有政策，此函數也會成功。如果您指定不存在的儲存貯體名稱，或如果您無法存取儲存貯體，`AmazonServiceException`則會擲出 。

請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/s3/delete_bucket_policy.cpp)。

## 詳細資訊
<a name="more-info"></a>
+  Amazon Simple Storage Service API 參考中的 [PutBucketPolicy](https://docs.aws.amazon.com/AmazonS3/latest/API/PutBucketPolicy.html) 
+  Amazon Simple Storage Service API 參考中的 [GetBucketPolicy](https://docs.aws.amazon.com/AmazonS3/latest/API/GetBucketPolicy.html) 
+  Amazon Simple Storage Service API 參考中的 [DeleteBucketPolicy](https://docs.aws.amazon.com/AmazonS3/latest/API/DeleteBucketPolicy.html) 
+  《Amazon Simple Storage Service 使用者指南》中的[存取政策語言概觀](https://docs.aws.amazon.com/AmazonS3/latest/dev/access-policy-language-overview.html) 
+  《Amazon Simple Storage Service 使用者指南》中的[儲存貯體政策範例](https://docs.aws.amazon.com/AmazonS3/latest/dev/example-bucket-policies.html)