本文属于机器翻译版本。若本译文内容与英语原文存在差异，则一律以英文原文为准。

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

以下 Java 示例显示了如何使用该[GetCertificate](https://docs.aws.amazon.com/privateca/latest/APIReference/API_GetCertificate.html)操作。

此操作可从您的私有 CA 检索证书。当您调用该操作时，将返回证书的 ARN。[IssueCertificate](https://docs.aws.amazon.com/privateca/latest/APIReference/API_IssueCertificate.html)在调用 `GetCertificate` 操作时，您必须同时指定私有 CA 的 ARN 和已颁发证书的 ARN。如果证书处于 `ISSUED` 状态，则可以检索该证书。您可以调用该[CreateCertificateAuthorityAuditReport](https://docs.aws.amazon.com/privateca/latest/APIReference/API_CreateCertificateAuthorityAuditReport.html)操作来创建一份报告，其中包含有关您的私有 CA 颁发和吊销的所有证书的信息。

```
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.GetCertificateRequest;
import com.amazonaws.services.acmpca.model.GetCertificateResult;

import com.amazonaws.AmazonClientException;
import com.amazonaws.services.acmpca.model.RequestInProgressException;
import com.amazonaws.services.acmpca.model.RequestFailedException ;
import com.amazonaws.services.acmpca.model.ResourceNotFoundException;
import com.amazonaws.services.acmpca.model.InvalidArnException;
import com.amazonaws.services.acmpca.model.InvalidStateException;

import com.amazonaws.waiters.Waiter;
import com.amazonaws.waiters.WaiterParameters;
import com.amazonaws.waiters.WaiterTimedOutException;
import com.amazonaws.waiters.WaiterUnrecoverableException;

import com.amazonaws.services.acmpca.model.AWSACMPCAException;

public class GetCertificate {

   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.
      AWSACMPCA client = AWSACMPCAClientBuilder.standard()
         .withEndpointConfiguration(endpoint)
         .withCredentials(new AWSStaticCredentialsProvider(credentials))
         .build();
         
      // Create a request object.
      GetCertificateRequest req = new GetCertificateRequest();

      // Set the certificate ARN.
      req.withCertificateArn("arn:aws:acm-pca:region:account:certificate-authority/CA_ID/certificate/certificate_ID");

      // Set the certificate authority ARN.
      req.withCertificateAuthorityArn("arn:aws:acm-pca:us-east-1:111122223333:certificate-authority/11223344-1234-1122-2233-112233445566");
            
      // Create waiter to wait on successful creation of the certificate file.
      Waiter<GetCertificateRequest> waiter = client.waiters().certificateIssued();
      try {
         waiter.run(new WaiterParameters<>(req));
      } catch (WaiterUnrecoverableException e) {
          //Explicit short circuit when the recourse transitions into
          //an undesired state.
      } catch (WaiterTimedOutException e) {
          //Failed to transition into desired state even after polling.
      } catch (AWSACMPCAException e) {
          //Unexpected service exception.
      }

      // Retrieve the certificate and certificate chain.
      GetCertificateResult result = null;
      try {
         result = client.getCertificate(req);
      } catch (RequestInProgressException ex) {
         throw ex;
      } catch (RequestFailedException ex) {
         throw ex;
      } catch (ResourceNotFoundException ex) {
         throw ex;
      } catch (InvalidArnException ex) {
         throw ex;
      } catch (InvalidStateException ex) {
         throw ex;
      }

      // Get the certificate and certificate chain and display the result.
      String strCert = result.getCertificate();
      System.out.println(strCert);
   }
}
```

对于证书颁发机构 (CA) 和您指定的证书，您的输出应该是类似如下的证书链。

```
-----BEGIN CERTIFICATE----- base64-encoded certificate -----END CERTIFICATE-----

-----BEGIN CERTIFICATE----- base64-encoded certificate -----END CERTIFICATE-----

-----BEGIN CERTIFICATE----- base64-encoded certificate -----END CERTIFICATE-----
```