尝试使用Java从S3桶下载文件，isStandardEndpoint上的Null指针异常

Question

我试图连接到S3桶并下载文件，但是代码会抛出异常：

在我的代码里

ProfileCredentialsProvider pcp = new ProfileCredentialsProvider("assumed_role");
        bucketName = "dev-data-extract-service-bucket";
s3Client = AmazonS3ClientBuilder.standard().withCredentials(pcp).withRegion(Regions.US_EAST_1.toString()).build();

调用以下行时会得到NullPointerException异常：

fullObject = s3Client.getObject(new GetObjectRequest(bucketName, "TR09_20190205.detail"));

原因是端点中的主机值为空，这是来自AmazonS3Client类的

private boolean isStandardEndpoint(URI endpoint) {
        return endpoint.getHost().endsWith("s3.amazonaws.com");
}

下面是堆栈跟踪

主调试com.amazonaws.monitoring.CsmConfigurationProviderChain -内部日志记录成功配置为公用记录器:真15:43:45.183主调试com.amazonaws.metrics.AwsSdkMetrics -在com.amazonaws.management:type=AwsSdkMetrics 15:43:45.952主调试com.amazonaws.monitoring.CsmConfigurationProviderChain下注册的管理mbean无法从com.amazonaws.monitoring.EnvironmentVariableCsmConfigurationProvider@169e6180:加载配置无法从环境变量加载客户端监视配置！15:43:45.952主调试com.amazonaws.monitoring.CsmConfigurationProviderChain-无法从com.amazonaws.monitoring.SystemPropertyCsmConfigurationProvider@35aea049:无法从系统属性变量加载客户端监视配置！15:43:45.952 java-sdk-http-连接--关闭空闲连接超过60000毫秒15:43:45.952主调试com.amazonaws.monitoring.CsmConfigurationProviderChain -无法从com.amazonaws.monitoring.ProfileCsmConfigurationProvider@611889f4:加载配置，无法在com的“主”java.lang.NullPointerException线程中加载配置文件异常.amazonaws.services.s3.AmazonS3Client.isStandardEndpoint(AmazonS3Client.java:3772) at com.amazonaws.services.s3.AmazonS3Client.noExplicitRegionProvided(AmazonS3Client.java:3767) at com.amazonaws.services.s3.AmazonS3Client.bucketRegionShouldBeCached(AmazonS3Client.java:4505) at com.amazonaws.services.s3.AmazonS3Client.shouldPerformHeadRequestToFindRegion(AmazonS3Client.java:4501) at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4426) at com.amazonaws.services.s3.AmazonS3Client.invoke( com.amazonaws.services.s3.AmazonS3Client.getAcl(AmazonS3Client.java:3573) at com.amazonaws.services.s3.AmazonS3Client.getBucketAcl(AmazonS3Client.java:1186) at com.amazonaws.services.s3.AmazonS3Client.getBucketAcl(AmazonS3Client.java:1176) at com.amazonaws.services.s3.AmazonS3Client.doesBucketExistV2(AmazonS3Client.java:1312) at .AWSHelper.downloadFromS3Bucket(AWSHelper.java:32) at .AWSHelper.main(AWSHelper.java:59) )

Answer 1

我认为你的问题源于你在这个地区的设置方式。我认为该区域正在解析为null，这导致您的端点为null。

而不是：

s3Client = AmazonS3ClientBuilder.standard().withCredentials(pcp).withRegion(Regions.US_EAST_1.toString()).build();

尝试：

s3Client = AmazonS3ClientBuilder.standard().withCredentials(pcp).withRegion(Regions.US_EAST_1).build();

Regions类不覆盖toString()方法，因此它不会返回区域名称，这是代码正常工作所需要的。