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# 列出集合
<a name="list-collection-procedure"></a>

您可以使用 [ListCollections](https://docs.aws.amazon.com/rekognition/latest/APIReference/API_ListCollections.html) 操作列出您正在使用的区域中的集合。

有关更多信息，请参阅 [管理集合](managing-face-collections.md#managing-collections)。



**列出集合 (SDK)**

1. 如果您尚未执行以下操作，请：

   1. 使用 `AmazonRekognitionFullAccess` 权限创建或更新用户。有关更多信息，请参阅 [步骤 1：设置 AWS 账户并创建用户](setting-up.md#setting-up-iam)。

   1. 安装并配置 AWS CLI 和 AWS SDKs。有关更多信息，请参阅 [第 2 步：设置 AWS CLI 和 AWS SDKs](setup-awscli-sdk.md)。

1. 使用以下示例调用 `ListCollections` 操作。

------
#### [ Java ]

   以下示例列出当前区域中的集合。

   ```
   //Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   //PDX-License-Identifier: MIT-0 (For details, see https://github.com/awsdocs/amazon-rekognition-developer-guide/blob/master/LICENSE-SAMPLECODE.)
   
   package aws.example.rekognition.image;
   
   import java.util.List;
   import com.amazonaws.services.rekognition.AmazonRekognition;
   import com.amazonaws.services.rekognition.AmazonRekognitionClientBuilder;
   import com.amazonaws.services.rekognition.model.ListCollectionsRequest;
   import com.amazonaws.services.rekognition.model.ListCollectionsResult;
   
   public class ListCollections {
   
      public static void main(String[] args) throws Exception {
   
   
         AmazonRekognition amazonRekognition = AmazonRekognitionClientBuilder.defaultClient();
    
   
         System.out.println("Listing collections");
         int limit = 10;
         ListCollectionsResult listCollectionsResult = null;
         String paginationToken = null;
         do {
            if (listCollectionsResult != null) {
               paginationToken = listCollectionsResult.getNextToken();
            }
            ListCollectionsRequest listCollectionsRequest = new ListCollectionsRequest()
                    .withMaxResults(limit)
                    .withNextToken(paginationToken);
            listCollectionsResult=amazonRekognition.listCollections(listCollectionsRequest);
            
            List < String > collectionIds = listCollectionsResult.getCollectionIds();
            for (String resultId: collectionIds) {
               System.out.println(resultId);
            }
         } while (listCollectionsResult != null && listCollectionsResult.getNextToken() !=
            null);
        
      } 
   }
   ```

------
#### [ Java V2 ]

   此代码取自 AWS 文档 SDK 示例 GitHub 存储库。请在[此处](https://github.com/awsdocs/aws-doc-sdk-examples/blob/master/javav2/example_code/rekognition/src/main/java/com/example/rekognition/ListCollections.java)查看完整示例。

   ```
   //snippet-start:[rekognition.java2.list_collections.import]
   import software.amazon.awssdk.auth.credentials.ProfileCredentialsProvider;
   import software.amazon.awssdk.regions.Region;
   import software.amazon.awssdk.services.rekognition.RekognitionClient;
   import software.amazon.awssdk.services.rekognition.model.ListCollectionsRequest;
   import software.amazon.awssdk.services.rekognition.model.ListCollectionsResponse;
   import software.amazon.awssdk.services.rekognition.model.RekognitionException;
   import java.util.List;
   //snippet-end:[rekognition.java2.list_collections.import]
   
   /**
   * Before running this Java V2 code example, set up your development environment, including your credentials.
   *
   * For more information, see the following documentation topic:
   *
   * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
   */
   public class ListCollections {
   
    public static void main(String[] args) {
   
        Region region = Region.US_EAST_1;
        RekognitionClient rekClient = RekognitionClient.builder()
            .region(region)
            .credentialsProvider(ProfileCredentialsProvider.create("profile-name"))
            .build();
   
        System.out.println("Listing collections");
        listAllCollections(rekClient);
        rekClient.close();
    }
   
    // snippet-start:[rekognition.java2.list_collections.main]
    public static void listAllCollections(RekognitionClient rekClient) {
        try {
            ListCollectionsRequest listCollectionsRequest = ListCollectionsRequest.builder()
                .maxResults(10)
                .build();
   
            ListCollectionsResponse response = rekClient.listCollections(listCollectionsRequest);
            List<String> collectionIds = response.collectionIds();
            for (String resultId : collectionIds) {
                System.out.println(resultId);
            }
   
        } catch (RekognitionException e) {
            System.out.println(e.getMessage());
            System.exit(1);
        }
    }
    // snippet-end:[rekognition.java2.list_collections.main]
   }
   ```

------
#### [ AWS CLI ]

   此 AWS CLI 命令显示 `list-collections` CLI 操作的 JSON 输出。将`profile_name`的值替换为您的开发人员资料的名称。

   ```
   aws rekognition list-collections --profile profile-name
   ```

------
#### [ Python ]

   以下示例列出当前区域中的集合。

    将创建 Rekognition 会话的行中的`profile_name`值替换为您的开发人员资料的名称。

   ```
   #Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   #PDX-License-Identifier: MIT-0 (For details, see https://github.com/awsdocs/amazon-rekognition-developer-guide/blob/master/LICENSE-SAMPLECODE.)
   
   import boto3
   
   def list_collections():
   
       max_results=2
       
       client=boto3.client('rekognition')
   
       #Display all the collections
       print('Displaying collections...')
       response=client.list_collections(MaxResults=max_results)
       collection_count=0
       done=False
       
       while done==False:
           collections=response['CollectionIds']
   
           for collection in collections:
               print (collection)
               collection_count+=1
           if 'NextToken' in response:
               nextToken=response['NextToken']
               response=client.list_collections(NextToken=nextToken,MaxResults=max_results)
               
           else:
               done=True
   
       return collection_count   
   
   def main():
   
       collection_count=list_collections()
       print("collections: " + str(collection_count))
   if __name__ == "__main__":
       main()
   ```

------
#### [ .NET ]

   以下示例列出当前区域中的集合。

   ```
   //Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   //PDX-License-Identifier: MIT-0 (For details, see https://github.com/awsdocs/amazon-rekognition-developer-guide/blob/master/LICENSE-SAMPLECODE.)
   
   using System;
   using Amazon.Rekognition;
   using Amazon.Rekognition.Model;
   
   public class ListCollections
   {
       public static void Example()
       {
           AmazonRekognitionClient rekognitionClient = new AmazonRekognitionClient();
   
           Console.WriteLine("Listing collections");
           int limit = 10;
   
           ListCollectionsResponse listCollectionsResponse = null;
           String paginationToken = null;
           do
           {
               if (listCollectionsResponse != null)
                   paginationToken = listCollectionsResponse.NextToken;
   
               ListCollectionsRequest listCollectionsRequest = new ListCollectionsRequest()
               {
                   MaxResults = limit,
                   NextToken = paginationToken
               };
   
               listCollectionsResponse = rekognitionClient.ListCollections(listCollectionsRequest);
   
               foreach (String resultId in listCollectionsResponse.CollectionIds)
                   Console.WriteLine(resultId);
           } while (listCollectionsResponse != null && listCollectionsResponse.NextToken != null);
       }
   }
   ```

------
#### [ Node.js ]

    将创建 Rekognition 会话的行中的`profile_name`值替换为您的开发人员资料的名称。

   ```
   //Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   //PDX-License-Identifier: MIT-0 (For details, see https://github.com/awsdocs/amazon-rekognition-developer-guide/blob/master/LICENSE-SAMPLECODE.)
   
   import { ListCollectionsCommand } from  "@aws-sdk/client-rekognition";
   import  { RekognitionClient } from "@aws-sdk/client-rekognition";
   import {fromIni} from '@aws-sdk/credential-providers';
   
   // Set the AWS Region.
   const REGION = "region-name"; //e.g. "us-east-1"
   // Set the profile name
   const profileName = "profile-name"
   // Name the collection
   const rekogClient = new RekognitionClient({region: REGION, 
     credentials: fromIni({profile: profileName,}), 
   });
   
   const listCollection = async () => {
     var max_results = 10
     console.log("Displaying collections:")
     var response = await rekogClient.send(new ListCollectionsCommand({MaxResults: max_results}))
     var collection_count = 0
     var done = false
     while (done == false){
         var collections = response.CollectionIds
         collections.forEach(collection => {
             console.log(collection)
             collection_count += 1
         });
         return collection_count
     }
   }
   
   var collect_list = await listCollection()
   console.log(collect_list)
   ```

------

## ListCollections 操作请求
<a name="listcollections-request"></a>

`ListCollections` 的输入是要返回的集合的最大数量。

```
{
    "MaxResults": 2
}
```

如果响应中包含的集合比 `MaxResults` 请求的人脸多，则会返回一个令牌，您可以使用此令牌在后续调用 `ListCollections` 时获得下一组结果。例如：

```
{
    "NextToken": "MGYZLAHX1T5a....",
    "MaxResults": 2
}
```

## ListCollections 操作响应
<a name="listcollections-operation-response"></a>

Amazon Rekognition 返回一系列集合（`CollectionIds`）。一个单独的数组 (`FaceModelVersions`) 提供用于分析每个集合中的人脸的人脸模型版本。例如，在下面的 JSON 响应中，集合 `MyCollection` 通过使用 2.0 版本的人脸模型来分析人脸。集合 `AnotherCollection` 使用 3.0 版本的人脸模型。有关更多信息，请参阅 [了解模型版本控制](face-detection-model.md)。

`NextToken` 是用于在后续调用 `ListCollections` 时获取下一组结果的令牌。

```
{
    "CollectionIds": [
        "MyCollection",
        "AnotherCollection"
    ],
    "FaceModelVersions": [
        "2.0",
        "3.0"
    ],
    "NextToken": "MGYZLAHX1T5a...."
}
```