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# ListTags
<a name="JavaApi-ListTags"></a>

以下 Java 示例显示了如何使用该[ListTags](https://docs.amazonaws.cn/privateca/latest/APIReference/API_ListTags.html)操作。

此操作可列出与您的私有 CA 关联的标签 (如果有)。标签是可用于识别和整理您的标签的标签 CAs。每个标签都由一个键和一个可选值组成。调用[TagCertificateAuthority](https://docs.amazonaws.cn/privateca/latest/APIReference/API_TagCertificateAuthority.html)操作将一个或多个标签添加到您的 CA。调用该[UntagCertificateAuthority](https://docs.amazonaws.cn/privateca/latest/APIReference/API_UntagCertificateAuthority.html)操作以移除标签。

```
package com.amazonaws.samples;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.client.builder.AwsClientBuilder;
import com.amazonaws.client.builder.AwsClientBuilder.EndpointConfiguration;
import com.amazonaws.auth.AWSStaticCredentialsProvider;

import com.amazonaws.services.acmpca.AWSACMPCA;
import com.amazonaws.services.acmpca.AWSACMPCAClientBuilder;

import com.amazonaws.services.acmpca.model.ListTagsRequest;
import com.amazonaws.services.acmpca.model.ListTagsResult;

import com.amazonaws.AmazonClientException;
import com.amazonaws.services.acmpca.model.ResourceNotFoundException;
import com.amazonaws.services.acmpca.model.InvalidArnException;

public class ListTags {

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

      // Retrieve your credentials from the C:\Users\name\.aws\credentials file
      // in Windows or the .aws/credentials file in Linux.
      AWSCredentials credentials = null;
      try {
          credentials = new ProfileCredentialsProvider("default").getCredentials();
      } catch (Exception e) {
          throw new AmazonClientException("Cannot load your credentials from disk", e);
      }

      // Define the endpoint for your sample.
      String endpointRegion = "{{region}}";  // Substitute your region here, e.g. "us-west-2"
      String endpointProtocol = "https://acm-pca." + endpointRegion + ".amazonaws.com/";
      EndpointConfiguration endpoint =
          new AwsClientBuilder.EndpointConfiguration(endpointProtocol, endpointRegion);

      // Create a client that you can use to make requests.
      AWSACMPCA client = AWSACMPCAClientBuilder.standard()
          .withEndpointConfiguration(endpoint)
          .withCredentials(new AWSStaticCredentialsProvider(credentials))
          .build();

      // Create a request object and set the CA ARN.
      ListTagsRequest req = new ListTagsRequest();
      req.withCertificateAuthorityArn("arn:{{aws}}:acm-pca:{{us-east-1}}:{{111122223333}}:certificate-authority/{{11223344-1234-1122-2233-112233445566}}");

      // List the tags
      ListTagsResult result = null;
      try {
          result = client.listTags(req);
      } catch (InvalidArnException ex) {
          throw ex;
      } catch (ResourceNotFoundException ex) {
          throw ex;
      }

      // Retrieve and display the tags.
      System.out.println(result);
   }
}
```

如果您有任何要列出的标签，则输出应类似于以下内容：

```
{Tags: [{Key: Admin,Value: Alice}, {Key: Purpose,Value: WebServices}],}
```