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 建立 IAM 政策 AWS SDK for Java 2.x
[IAM 政策建置器 API](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/policybuilder/iam/package-summary.html) 是一個程式庫，可用於在 Java 中建置 [IAM 政策](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html)並將其上傳至 AWS Identity and Access Management (IAM)。
API 提供用戶端、物件導向方法來產生 JSON 字串，而不是透過手動組合 JSON 字串或讀取檔案來建置 IAM 政策。當您讀取 JSON 格式的現有 IAM 政策時，API 會將其轉換為 [IamPolicy](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/policybuilder/iam/IamPolicy.html) 執行個體進行處理。
IAM 政策建置器 API 隨 SDK 2.20.105 版推出，因此請在 Maven 建置檔案中使用該版本或更新版本。開發套件的最新版本編號[列於 Maven 中央](https://central.sonatype.com/artifact/software.amazon.awssdk/iam-policy-builder)。
下列程式碼片段顯示 Maven `pom.xml` 檔案的範例相依性區塊。這可讓您在專案中使用 IAM 政策建置器 API。
```
software.amazon.awssdk
iam-policy-builder
2.27.21
```
## 建立 `IamPolicy`
本節顯示數個如何使用 IAM 政策建置器 API 建置政策的範例。
在下列每個範例中，從 開始`[IamPolicy.Builder](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/policybuilder/iam/IamPolicy.Builder.html)`，並使用 `addStatement`方法新增一或多個陳述式。在此模式之後，[IamStatement.Builder](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/policybuilder/iam/IamStatement.Builder.html) 具有將效果、動作、資源和條件新增至陳述式的方法。
### 範例：建立以時間為基礎的政策
下列範例會建立身分型政策，允許在兩個時間點之間執行 Amazon DynamoDB `GetItem`動作。
```
public String timeBasedPolicyExample() {
IamPolicy policy = IamPolicy.builder()
.addStatement(b -> b
.effect(IamEffect.ALLOW)
.addAction("dynamodb:GetItem")
.addResource(IamResource.ALL)
.addCondition(b1 -> b1
.operator(IamConditionOperator.DATE_GREATER_THAN)
.key("aws:CurrentTime")
.value("2020-04-01T00:00:00Z"))
.addCondition(b1 -> b1
.operator(IamConditionOperator.DATE_LESS_THAN)
.key("aws:CurrentTime")
.value("2020-06-30T23:59:59Z")))
.build();
// Use an IamPolicyWriter to write out the JSON string to a more readable format.
return policy.toJson(IamPolicyWriter.builder()
.prettyPrint(true)
.build());
}
```
#### JSON 輸出
上一個範例中的最後一個陳述式會傳回下列 JSON 字串。
閱讀*AWS Identity and Access Management 《 使用者指南*》中有關此[範例](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_examples_aws-dates.html)的詳細資訊。
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": "dynamodb:GetItem",
"Resource": "*",
"Condition": {
"DateGreaterThan": {
"aws:CurrentTime": "2020-04-01T00:00:00Z"
},
"DateLessThan": {
"aws:CurrentTime": "2020-06-30T23:59:59Z"
}
}
}
}
```
------
### 範例：指定多個條件
下列範例示範如何建立身分型政策，允許存取特定 DynamoDB 屬性。政策包含兩個條件。
```
public String multipleConditionsExample() {
IamPolicy policy = IamPolicy.builder()
.addStatement(b -> b
.effect(IamEffect.ALLOW)
.addAction("dynamodb:GetItem")
.addAction("dynamodb:BatchGetItem")
.addAction("dynamodb:Query")
.addAction("dynamodb:PutItem")
.addAction("dynamodb:UpdateItem")
.addAction("dynamodb:DeleteItem")
.addAction("dynamodb:BatchWriteItem")
.addResource("arn:aws:dynamodb:*:*:table/table-name")
.addConditions(IamConditionOperator.STRING_EQUALS.addPrefix("ForAllValues:"),
"dynamodb:Attributes",
List.of("column-name1", "column-name2", "column-name3"))
.addCondition(b1 -> b1.operator(IamConditionOperator.STRING_EQUALS.addSuffix("IfExists"))
.key("dynamodb:Select")
.value("SPECIFIC_ATTRIBUTES")))
.build();
return policy.toJson(IamPolicyWriter.builder()
.prettyPrint(true).build());
}
```
#### JSON 輸出
上一個範例中的最後一個陳述式會傳回下列 JSON 字串。
閱讀*AWS Identity and Access Management 《 使用者指南*》中有關此[範例](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_examples_dynamodb_attributes.html)的詳細資訊。
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": {
"Effect": "Allow",
"Action": [
"dynamodb:GetItem",
"dynamodb:BatchGetItem",
"dynamodb:Query",
"dynamodb:PutItem",
"dynamodb:UpdateItem",
"dynamodb:DeleteItem",
"dynamodb:BatchWriteItem"
],
"Resource": "arn:aws:dynamodb:*:*:table/table-name",
"Condition": {
"ForAllValues:StringEquals": {
"dynamodb:Attributes": [
"column-name1",
"column-name2",
"column-name3"
]
},
"StringEqualsIfExists": {
"dynamodb:Select": "SPECIFIC_ATTRIBUTES"
}
}
}
}
```
------
### 範例：指定主體
下列範例示範如何建立以資源為基礎的政策，拒絕存取條件中指定的所有主體的儲存貯體。
```
public String specifyPrincipalsExample() {
IamPolicy policy = IamPolicy.builder()
.addStatement(b -> b
.effect(IamEffect.DENY)
.addAction("s3:*")
.addPrincipal(IamPrincipal.ALL)
.addResource("arn:aws:s3:::BUCKETNAME/*")
.addResource("arn:aws:s3:::BUCKETNAME")
.addCondition(b1 -> b1
.operator(IamConditionOperator.ARN_NOT_EQUALS)
.key("aws:PrincipalArn")
.value("arn:aws:iam::444455556666:user/user-name")))
.build();
return policy.toJson(IamPolicyWriter.builder()
.prettyPrint(true).build());
}
```
#### JSON 輸出
上一個範例中的最後一個陳述式會傳回下列 JSON 字串。
閱讀*AWS Identity and Access Management 《 使用者指南*》中有關此[範例](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html#principal-anonymous)的詳細資訊。
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement" : {
"Effect" : "Deny",
"Principal" : "*",
"Action" : "s3:*",
"Resource" : [ "arn:aws:s3:::BUCKETNAME/*", "arn:aws:s3:::BUCKETNAME" ],
"Condition" : {
"ArnNotEquals" : {
"aws:PrincipalArn" : "arn:aws:iam::444455556666:user/user-name"
}
}
}
}
```
------
### 範例：允許跨帳戶存取
下列範例顯示如何允許另一個 AWS 帳戶 將物件上傳至您的儲存貯體，同時保留已上傳物件的完整擁有者控制。
```
public String allowCrossAccountAccessExample() {
IamPolicy policy = IamPolicy.builder()
.addStatement(b -> b
.effect(IamEffect.ALLOW)
.addPrincipal(IamPrincipalType.AWS, "111122223333")
.addAction("s3:PutObject")
.addResource("arn:aws:s3:::amzn-s3-demo-bucket/*")
.addCondition(b1 -> b1
.operator(IamConditionOperator.STRING_EQUALS)
.key("s3:x-amz-acl")
.value("bucket-owner-full-control")))
.build();
return policy.toJson(IamPolicyWriter.builder()
.prettyPrint(true).build());
}
```
#### JSON 輸出
上一個範例中的最後一個陳述式會傳回下列 JSON 字串。
閱讀《*Amazon Simple Storage Service 使用者指南*》中有關此[範例](https://docs.aws.amazon.com/AmazonS3/latest/userguide/example-bucket-policies.html#example-bucket-policies-acl-2)的詳細資訊。
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement" : {
"Effect" : "Allow",
"Principal" : {
"AWS" : "111122223333"
},
"Action" : "s3:PutObject",
"Resource" : "arn:aws:s3:::amzn-s3-demo-bucket/*",
"Condition" : {
"StringEquals" : {
"s3:x-amz-acl" : "bucket-owner-full-control"
}
}
}
}
```
------
## `IamPolicy` 搭配 IAM 使用
建立`IamPolicy`執行個體之後，您可以使用 [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/IamClient.html](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/iam/IamClient.html) 來使用 IAM 服務。
下列範例會建置政策，允許 [IAM 身分](https://docs.aws.amazon.com/IAM/latest/UserGuide/id.html)將項目寫入使用 `accountID` 參數指定的帳戶中的 DynamoDB 資料表。然後，政策會以 JSON 字串的形式上傳至 IAM。
```
public String createAndUploadPolicyExample(IamClient iam, String accountID, String policyName) {
// Build the policy.
IamPolicy policy =
IamPolicy.builder() // 'version' defaults to "2012-10-17".
.addStatement(IamStatement.builder()
.effect(IamEffect.ALLOW)
.addAction("dynamodb:PutItem")
.addResource("arn:aws:dynamodb:us-east-1:" + accountID + ":table/exampleTableName")
.build())
.build();
// Upload the policy.
iam.createPolicy(r -> r.policyName(policyName).policyDocument(policy.toJson()));
return policy.toJson(IamPolicyWriter.builder().prettyPrint(true).build());
}
```
下一個範例以先前的範例為基礎。程式碼會下載政策，並透過複製和修改陳述式，將其用作新政策的基礎。然後上傳新的政策。
```
public String createNewBasedOnExistingPolicyExample(IamClient iam, String accountID, String policyName, String newPolicyName) {
String policyArn = "arn:aws:iam::" + accountID + ":policy/" + policyName;
GetPolicyResponse getPolicyResponse = iam.getPolicy(r -> r.policyArn(policyArn));
String policyVersion = getPolicyResponse.policy().defaultVersionId();
GetPolicyVersionResponse getPolicyVersionResponse =
iam.getPolicyVersion(r -> r.policyArn(policyArn).versionId(policyVersion));
// Create an IamPolicy instance from the JSON string returned from IAM.
String decodedPolicy = URLDecoder.decode(getPolicyVersionResponse.policyVersion().document(), StandardCharsets.UTF_8);
IamPolicy policy = IamPolicy.fromJson(decodedPolicy);
/*
All IamPolicy components are immutable, so use the copy method that creates a new instance that
can be altered in the same method call.
Add the ability to get an item from DynamoDB as an additional action.
*/
IamStatement newStatement = policy.statements().get(0).copy(s -> s.addAction("dynamodb:GetItem"));
// Create a new statement that replaces the original statement.
IamPolicy newPolicy = policy.copy(p -> p.statements(Arrays.asList(newStatement)));
// Upload the new policy. IAM now has both policies.
iam.createPolicy(r -> r.policyName(newPolicyName)
.policyDocument(newPolicy.toJson()));
return newPolicy.toJson(IamPolicyWriter.builder().prettyPrint(true).build());
}
```
### IamClient
上述範例使用建立的 `IamClient` 引數，如下列程式碼片段所示。
```
IamClient iam = IamClient.builder().region(Region.AWS_GLOBAL).build();
```
### JSON 中的政策
這些範例會傳回下列 JSON 字串。
```
First example
{
"Version": "2012-10-17",
"Statement" : {
"Effect" : "Allow",
"Action" : "dynamodb:PutItem",
"Resource" : "arn:aws:dynamodb:us-east-1:111122223333:table/exampleTableName"
}
}
Second example
{
"Version": "2012-10-17",
"Statement" : {
"Effect" : "Allow",
"Action" : [ "dynamodb:PutItem", "dynamodb:GetItem" ],
"Resource" : "arn:aws:dynamodb:us-east-1:111122223333:table/exampleTableName"
}
}
```