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# 使用 IAM 策略
<a name="examples-iam-policies"></a>

## 创建策略
<a name="create-a-policy"></a>

要创建新策略，请在 [CreatePolicyRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/model/CreatePolicyRequest.html) 中向 IamClient 的 `createPolicy` 方法提供策略名称和 JSON 格式的策略文档。

 **导入**。

```
import software.amazon.awssdk.core.waiters.WaiterResponse;
import software.amazon.awssdk.services.iam.model.CreatePolicyRequest;
import software.amazon.awssdk.services.iam.model.CreatePolicyResponse;
import software.amazon.awssdk.services.iam.model.GetPolicyRequest;
import software.amazon.awssdk.services.iam.model.GetPolicyResponse;
import software.amazon.awssdk.services.iam.model.IamException;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.iam.IamClient;
import software.amazon.awssdk.services.iam.waiters.IamWaiter;
```

 **代码** 

```
    public static String createIAMPolicy(IamClient iam, String policyName ) {

        try {
            // Create an IamWaiter object
            IamWaiter iamWaiter = iam.waiter();

            CreatePolicyRequest request = CreatePolicyRequest.builder()
                .policyName(policyName)
                .policyDocument(PolicyDocument).build();

            CreatePolicyResponse response = iam.createPolicy(request);

            // Wait until the policy is created
            GetPolicyRequest polRequest = GetPolicyRequest.builder()
                    .policyArn(response.policy().arn())
                    .build();

            WaiterResponse<GetPolicyResponse> waitUntilPolicyExists = iamWaiter.waitUntilPolicyExists(polRequest);
            waitUntilPolicyExists.matched().response().ifPresent(System.out::println);
            return response.policy().arn();

         } catch (IamException e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
        return "" ;
    }
```

请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/e41bacfd5e671e7ef1a9f73e972540dc6a434664/javav2/example_code/iam/src/main/java/com/example/iam/CreatePolicy.java)。

## 获取策略
<a name="get-a-policy"></a>

要检索现有策略，请调用 IamClient 的 `getPolicy` 方法，并在 [GetPolicyRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/model/GetPolicyRequest.html) 对象中提供策略的 ARN。

 **导入**。

```
import software.amazon.awssdk.services.iam.model.GetPolicyRequest;
import software.amazon.awssdk.services.iam.model.GetPolicyResponse;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.iam.IamClient;
import software.amazon.awssdk.services.iam.model.IamException;
```

 **代码** 

```
    public static void getIAMPolicy(IamClient iam, String policyArn) {

        try {
            GetPolicyRequest request = GetPolicyRequest.builder()
                .policyArn(policyArn).build();

            GetPolicyResponse response = iam.getPolicy(request);
            System.out.format("Successfully retrieved policy %s",
                response.policy().policyName());

        } catch (IamException e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }
```

请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/cf25559da654a7b74bec039c0ab9397dc5951dd4/javav2/example_code/iam/src/main/java/com/example/iam/GetPolicy.java)。

## 附加角色策略
<a name="attach-a-role-policy"></a>

您可以将策略附加到 IAM [角色](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html)，方式是调用 IamClient 的 `attachRolePolicy` 方法，并在 [AttachRolePolicyRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/model/AttachRolePolicyRequest.html) 中为其提供角色名称和策略 ARN。

 **导入**。

```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.iam.IamClient;
import software.amazon.awssdk.services.iam.model.IamException;
import software.amazon.awssdk.services.iam.model.AttachRolePolicyRequest;
import software.amazon.awssdk.services.iam.model.AttachedPolicy;
import software.amazon.awssdk.services.iam.model.ListAttachedRolePoliciesRequest;
import software.amazon.awssdk.services.iam.model.ListAttachedRolePoliciesResponse;
import java.util.List;
```

 **代码** 

```
    public static void attachIAMRolePolicy(IamClient iam, String roleName, String policyArn ) {

        try {

             ListAttachedRolePoliciesRequest request = ListAttachedRolePoliciesRequest.builder()
                    .roleName(roleName)
                    .build();

            ListAttachedRolePoliciesResponse  response = iam.listAttachedRolePolicies(request);
            List<AttachedPolicy> attachedPolicies = response.attachedPolicies();

            // Ensure that the policy is not attached to this role
            String polArn = "";
            for (AttachedPolicy policy: attachedPolicies) {
                polArn = policy.policyArn();
                if (polArn.compareTo(policyArn)==0) {
                   System.out.println(roleName +
                            " policy is already attached to this role.");
                    return;
                }
          }

            AttachRolePolicyRequest attachRequest =
                AttachRolePolicyRequest.builder()
                        .roleName(roleName)
                        .policyArn(policyArn)
                        .build();

            iam.attachRolePolicy(attachRequest);

            System.out.println("Successfully attached policy " + policyArn +
                " to role " + roleName);

         } catch (IamException e) {
                System.err.println(e.awsErrorDetails().errorMessage());
                System.exit(1);
          }

     System.out.println("Done");
    }
```

请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/cf25559da654a7b74bec039c0ab9397dc5951dd4/javav2/example_code/iam/src/main/java/com/example/iam/AttachRolePolicy.java)。

## 列出附加的角色策略
<a name="list-attached-role-policies"></a>

通过调用 IamClient 的 `listAttachedRolePolicies` 方法列出角色中附加的策略。这需要 [ListAttachedRolePoliciesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/model/ListAttachedRolePoliciesRequest.html) 对象，它包含要列出策略的角色名称。

在返回的 [ListAttachedRolePoliciesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/model/ListAttachedRolePoliciesResponse.html) 对象上调用 `getAttachedPolicies` 来获取所附加策略的列表。结果可能被截断；如果 `ListAttachedRolePoliciesResponse` 对象的 `isTruncated` 方法返回了 `true`，请调用 `ListAttachedRolePoliciesResponse` 对象的 `marker` 方法。使用返回的标记创建新请求并使用该请求再次调用 `listAttachedRolePolicies` 以获取下一批结果。

 **导入**。

```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.iam.IamClient;
import software.amazon.awssdk.services.iam.model.IamException;
import software.amazon.awssdk.services.iam.model.AttachRolePolicyRequest;
import software.amazon.awssdk.services.iam.model.AttachedPolicy;
import software.amazon.awssdk.services.iam.model.ListAttachedRolePoliciesRequest;
import software.amazon.awssdk.services.iam.model.ListAttachedRolePoliciesResponse;
import java.util.List;
```

 **代码** 

```
    public static void attachIAMRolePolicy(IamClient iam, String roleName, String policyArn ) {

        try {

             ListAttachedRolePoliciesRequest request = ListAttachedRolePoliciesRequest.builder()
                    .roleName(roleName)
                    .build();

            ListAttachedRolePoliciesResponse  response = iam.listAttachedRolePolicies(request);
            List<AttachedPolicy> attachedPolicies = response.attachedPolicies();

            // Ensure that the policy is not attached to this role
            String polArn = "";
            for (AttachedPolicy policy: attachedPolicies) {
                polArn = policy.policyArn();
                if (polArn.compareTo(policyArn)==0) {
                   System.out.println(roleName +
                            " policy is already attached to this role.");
                    return;
                }
          }

            AttachRolePolicyRequest attachRequest =
                AttachRolePolicyRequest.builder()
                        .roleName(roleName)
                        .policyArn(policyArn)
                        .build();

            iam.attachRolePolicy(attachRequest);

            System.out.println("Successfully attached policy " + policyArn +
                " to role " + roleName);

         } catch (IamException e) {
                System.err.println(e.awsErrorDetails().errorMessage());
                System.exit(1);
          }

     System.out.println("Done");
    }
```

请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/cf25559da654a7b74bec039c0ab9397dc5951dd4/javav2/example_code/iam/src/main/java/com/example/iam/AttachRolePolicy.java)。

## 分离角色策略
<a name="detach-a-role-policy"></a>

要从角色分离策略，请调用 IamClient 的 `detachRolePolicy` 方法，并在 [DetachRolePolicyRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/model/DetachRolePolicyRequest.html) 中为其提供角色名称和策略 ARN。

 **导入**。

```
import software.amazon.awssdk.services.iam.model.DetachRolePolicyRequest;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.iam.IamClient;
import software.amazon.awssdk.services.iam.model.IamException;
```

 **代码** 

```
    public static void detachPolicy(IamClient iam, String roleName, String policyArn ) {

        try {
            DetachRolePolicyRequest request = DetachRolePolicyRequest.builder()
                    .roleName(roleName)
                    .policyArn(policyArn)
                    .build();

            iam.detachRolePolicy(request);
            System.out.println("Successfully detached policy " + policyArn +
                " from role " + roleName);

        } catch (IamException e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }
```

请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/cf25559da654a7b74bec039c0ab9397dc5951dd4/javav2/example_code/iam/src/main/java/com/example/iam/DetachRolePolicy.java)。

## 更多信息
<a name="more-information"></a>
+  《IAM 用户指南》中的 [IAM 策略概述](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html)。
+ 《IAM 用户指南》中的 [AWS IAM policy 参考](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies.html)。
+  《IAM API Reference》中的 [CreatePolicy](https://docs.aws.amazon.com/IAM/latest/APIReference/API_CreatePolicy.html)
+  《IAM API Reference》中的 [GetPolicy](https://docs.aws.amazon.com/IAM/latest/APIReference/API_GetPolicy.html)
+  《IAM API Reference》中的 [AttachRolePolicy](https://docs.aws.amazon.com/IAM/latest/APIReference/API_AttachRolePolicy.html)
+  《IAM API Reference》中的 [ListAttachedRolePolicies](https://docs.aws.amazon.com/IAM/latest/APIReference/API_ListAttachedRolePolicies.html)
+  《IAM API Reference》中的 [DetachRolePolicy](https://docs.aws.amazon.com/IAM/latest/APIReference/API_DetachRolePolicy.html)