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# 使用 Amazon EC2
本部分提供使用适用于 Java 的 AWS SDK 2.x 对 [Amazon EC2](https://docs.aws.amazon.com/ec2/) 进行编程的示例。
**Topics**
+ [管理 Amazon EC2 实例](examples-ec2-instances.md)
+ [使用 AWS 区域 区和可用区](examples-ec2-regions-zones.md)
+ [在 Amazon EC2 中使用安全组](examples-ec2-security-groups.md)
+ [使用 Amazon EC2 实例元数据](examples-ec2-IMDS.md)
# 管理 Amazon EC2 实例
## 创建实例
通过调用 [Ec2Client](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html) 的[https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#runInstances(software.amazon.awssdk.services.ec2.model.RunInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#runInstances(software.amazon.awssdk.services.ec2.model.RunInstancesRequest))方法创建一个新 Amazon EC2 实例，为其提供[RunInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/RunInstancesRequest.html)包含要使用的[亚马逊系统映像 (AMI)](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/AMIs.html) 和[实例](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/instance-types.html)类型。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.InstanceType;
import software.amazon.awssdk.services.ec2.model.RunInstancesRequest;
import software.amazon.awssdk.services.ec2.model.RunInstancesResponse;
import software.amazon.awssdk.services.ec2.model.Tag;
import software.amazon.awssdk.services.ec2.model.CreateTagsRequest;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
```
**代码**
```
public static String createEC2Instance(Ec2Client ec2,String name, String amiId ) {
RunInstancesRequest runRequest = RunInstancesRequest.builder()
.imageId(amiId)
.instanceType(InstanceType.T1_MICRO)
.maxCount(1)
.minCount(1)
.build();
RunInstancesResponse response = ec2.runInstances(runRequest);
String instanceId = response.instances().get(0).instanceId();
Tag tag = Tag.builder()
.key("Name")
.value(name)
.build();
CreateTagsRequest tagRequest = CreateTagsRequest.builder()
.resources(instanceId)
.tags(tag)
.build();
try {
ec2.createTags(tagRequest);
System.out.printf(
"Successfully started EC2 Instance %s based on AMI %s",
instanceId, amiId);
return instanceId;
} catch (Ec2Exception e) {
System.err.println(e.awsErrorDetails().errorMessage());
System.exit(1);
}
return "";
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/CreateInstance.java) GitHub。
## 启动实例
要启动 Amazon EC2 实例，请调用 Ec2Client [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#startInstances(software.amazon.awssdk.services.ec2.model.StartInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#startInstances(software.amazon.awssdk.services.ec2.model.StartInstancesRequest))的方法，为其提供[StartInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/StartInstancesRequest.html)包含要启动的实例的 ID。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.StartInstancesRequest;
import software.amazon.awssdk.services.ec2.model.StopInstancesRequest;
```
**代码**
```
public static void startInstance(Ec2Client ec2, String instanceId) {
StartInstancesRequest request = StartInstancesRequest.builder()
.instanceIds(instanceId)
.build();
ec2.startInstances(request);
System.out.printf("Successfully started instance %s", instanceId);
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/StartStopInstance.java) GitHub。
## 停止实例
要停止 Amazon EC2 实例，请调用 Ec2Client [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#stopInstances(software.amazon.awssdk.services.ec2.model.StopInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#stopInstances(software.amazon.awssdk.services.ec2.model.StopInstancesRequest))的方法，为其提供[StopInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/StopInstancesRequest.html)包含要停止的实例的 ID。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.StartInstancesRequest;
import software.amazon.awssdk.services.ec2.model.StopInstancesRequest;
```
**代码**
```
public static void stopInstance(Ec2Client ec2, String instanceId) {
StopInstancesRequest request = StopInstancesRequest.builder()
.instanceIds(instanceId)
.build();
ec2.stopInstances(request);
System.out.printf("Successfully stopped instance %s", instanceId);
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/StartStopInstance.java) GitHub。
## 重启实例
要重启 Amazon EC2 实例，请调用 Ec2Client [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#rebootInstances(software.amazon.awssdk.services.ec2.model.RebootInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#rebootInstances(software.amazon.awssdk.services.ec2.model.RebootInstancesRequest))的方法，为其提供[RebootInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/RebootInstancesRequest.html)包含要重启的实例 ID。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
import software.amazon.awssdk.services.ec2.model.RebootInstancesRequest;
```
**代码**
```
public static void rebootEC2Instance(Ec2Client ec2, String instanceId) {
try {
RebootInstancesRequest request = RebootInstancesRequest.builder()
.instanceIds(instanceId)
.build();
ec2.rebootInstances(request);
System.out.printf(
"Successfully rebooted instance %s", instanceId);
} catch (Ec2Exception e) {
System.err.println(e.awsErrorDetails().errorMessage());
System.exit(1);
}
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/RebootInstance.java) GitHub。
## 描述实例
要列出您的实例，请创建[DescribeInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeInstancesRequest.html)并调用 Ec2Client [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#describeInstances(software.amazon.awssdk.services.ec2.model.DescribeInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#describeInstances(software.amazon.awssdk.services.ec2.model.DescribeInstancesRequest))的方法。它将返回一个[DescribeInstancesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeInstancesResponse.html)对象，您可以使用该对象列出您的账户和地区的 Amazon EC2 实例。
实例按*预留*进行分组。每个预留对应对启动实例的 `startInstances` 的调用。要列出您的实例，您必须先调用 `DescribeInstancesResponse` 类的 `reservations` 方法，然后在每个返回的 `instances`Reservation[ 对象上调用 ](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/Reservation.html)。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.DescribeInstancesRequest;
import software.amazon.awssdk.services.ec2.model.DescribeInstancesResponse;
import software.amazon.awssdk.services.ec2.model.Instance;
import software.amazon.awssdk.services.ec2.model.Reservation;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
```
**代码**
```
public static void describeEC2Instances( Ec2Client ec2){
String nextToken = null;
try {
do {
DescribeInstancesRequest request = DescribeInstancesRequest.builder().maxResults(6).nextToken(nextToken).build();
DescribeInstancesResponse response = ec2.describeInstances(request);
for (Reservation reservation : response.reservations()) {
for (Instance instance : reservation.instances()) {
System.out.println("Instance Id is " + instance.instanceId());
System.out.println("Image id is "+ instance.imageId());
System.out.println("Instance type is "+ instance.instanceType());
System.out.println("Instance state name is "+ instance.state().name());
System.out.println("monitoring information is "+ instance.monitoring().state());
}
}
nextToken = response.nextToken();
} while (nextToken != null);
} catch (Ec2Exception e) {
System.err.println(e.awsErrorDetails().errorMessage());
System.exit(1);
}
}
```
结果将分页；您可以获取更多结果，方法是将从结果对象的 `nextToken` 方法返回的值传递到新请求对象的 `nextToken` 方法，然后在下一个 `describeInstances` 调用中使用新请求对象。
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeInstances.java) GitHub。
## 监控实例
您可以监控 Amazon EC2 实例的各个方面，例如 CPU 和网络利用率、可用内存和剩余磁盘空间。要了解有关实例监控的更多信息，请参阅 Linux 实例 Amazon EC2 用户指南 Amazon EC2中的[监控](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/monitoring_ec2.html)。
要开始监控实例，您必须[MonitorInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/MonitorInstancesRequest.html)使用要监控的实例的 ID 创建一个，并将其传递给 Ec2Client [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#monitorInstances(software.amazon.awssdk.services.ec2.model.MonitorInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#monitorInstances(software.amazon.awssdk.services.ec2.model.MonitorInstancesRequest))的方法。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.MonitorInstancesRequest;
import software.amazon.awssdk.services.ec2.model.UnmonitorInstancesRequest;
```
**代码**
```
public static void monitorInstance( Ec2Client ec2, String instanceId) {
MonitorInstancesRequest request = MonitorInstancesRequest.builder()
.instanceIds(instanceId).build();
ec2.monitorInstances(request);
System.out.printf(
"Successfully enabled monitoring for instance %s",
instanceId);
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/MonitorInstance.java) GitHub。
## 停止实例监控
要停止监控实例，请[UnmonitorInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/UnmonitorInstancesRequest.html)使用要停止监控的实例 ID 创建一个，然后将其传递给 Ec2Client [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#unmonitorInstances(software.amazon.awssdk.services.ec2.model.UnmonitorInstancesRequest)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/Ec2Client.html#unmonitorInstances(software.amazon.awssdk.services.ec2.model.UnmonitorInstancesRequest))的方法。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.MonitorInstancesRequest;
import software.amazon.awssdk.services.ec2.model.UnmonitorInstancesRequest;
```
**代码**
```
public static void unmonitorInstance(Ec2Client ec2, String instanceId) {
UnmonitorInstancesRequest request = UnmonitorInstancesRequest.builder()
.instanceIds(instanceId).build();
ec2.unmonitorInstances(request);
System.out.printf(
"Successfully disabled monitoring for instance %s",
instanceId);
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/MonitorInstance.java) GitHub。
## 更多信息
+ [RunInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_RunInstances.html)在 Amazon EC2 API 参考中
+ [DescribeInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstances.html)在 Amazon EC2 API 参考中
+ [StartInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_StartInstances.html)在 Amazon EC2 API 参考中
+ [StopInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_StopInstances.html)在 Amazon EC2 API 参考中
+ [RebootInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_RebootInstances.html)在 Amazon EC2 API 参考中
+ [MonitorInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_MonitorInstances.html)在 Amazon EC2 API 参考中
+ [UnmonitorInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_UnmonitorInstances.html)在 Amazon EC2 API 参考中
# 使用 AWS 区域 区和可用区
## 描述区域
要列出账户可用的区域，请调用 Ec2Client 的 `describeRegions` 方法。它返回 [DescribeRegionsResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeRegionsResponse.html)。调用返回对象的 `regions` 方法，获取表示各个区域的 [Region](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/Region.html) 对象的列表。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2AsyncClient;
import software.amazon.awssdk.services.ec2.model.DescribeRegionsResponse;
import software.amazon.awssdk.services.ec2.model.DescribeAvailabilityZonesResponse;
import java.util.concurrent.CompletableFuture;
```
**代码**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2AsyncClient;
import software.amazon.awssdk.services.ec2.model.DescribeRegionsResponse;
import software.amazon.awssdk.services.ec2.model.DescribeAvailabilityZonesResponse;
import java.util.concurrent.CompletableFuture;
/**
* 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 DescribeRegionsAndZones {
public static void main(String[] args) {
Ec2AsyncClient ec2AsyncClient = Ec2AsyncClient.builder()
.region(Region.US_EAST_1)
.build();
try {
CompletableFuture future = describeEC2RegionsAndZonesAsync(ec2AsyncClient);
future.join(); // Wait for both async operations to complete.
} catch (RuntimeException rte) {
System.err.println("An exception occurred: " + (rte.getCause() != null ? rte.getCause().getMessage() : rte.getMessage()));
}
}
/**
* Asynchronously describes the EC2 regions and availability zones.
*
* @param ec2AsyncClient the EC2 async client used to make the API calls
* @return a {@link CompletableFuture} that completes when both the region and availability zone descriptions are complete
*/
public static CompletableFuture describeEC2RegionsAndZonesAsync(Ec2AsyncClient ec2AsyncClient) {
// Initiate the asynchronous request to describe regions
CompletableFuture regionsResponse = ec2AsyncClient.describeRegions();
// Handle the response or exception for regions
CompletableFuture regionsFuture = regionsResponse.whenComplete((regionsResp, ex) -> {
if (ex != null) {
// Handle the exception by throwing a RuntimeException
throw new RuntimeException("Failed to describe EC2 regions.", ex);
} else if (regionsResp == null || regionsResp.regions().isEmpty()) {
// Throw an exception if the response is null or the result is empty
throw new RuntimeException("No EC2 regions found.");
} else {
// Process the response if no exception occurred and the result is not empty
regionsResp.regions().forEach(region -> {
System.out.printf(
"Found Region %s with endpoint %s%n",
region.regionName(),
region.endpoint());
});
}
});
CompletableFuture zonesResponse = ec2AsyncClient.describeAvailabilityZones();
CompletableFuture zonesFuture = zonesResponse.whenComplete((zonesResp, ex) -> {
if (ex != null) {
throw new RuntimeException("Failed to describe EC2 availability zones.", ex);
} else if (zonesResp == null || zonesResp.availabilityZones().isEmpty()) {
throw new RuntimeException("No EC2 availability zones found.");
} else {
zonesResp.availabilityZones().forEach(zone -> {
System.out.printf(
"Found Availability Zone %s with status %s in region %s%n",
zone.zoneName(),
zone.state(),
zone.regionName()
);
});
}
});
return CompletableFuture.allOf(regionsFuture, zonesFuture);
}
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/7486a1a092aa8e16a21698ef26f9d524fef62e55/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeRegionsAndZones.java) GitHub。
## 描述可用区
要列出账户可用的每个可用区，请调用 Ec2Client 的 `describeAvailabilityZones` 方法。它返回 [DescribeAvailabilityZonesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeAvailabilityZonesResponse.html)。调用其`availabilityZones`方法以获取代表每个可用区的[AvailabilityZone](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AvailabilityZone.html)对象列表。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2AsyncClient;
import software.amazon.awssdk.services.ec2.model.DescribeRegionsResponse;
import software.amazon.awssdk.services.ec2.model.DescribeAvailabilityZonesResponse;
import java.util.concurrent.CompletableFuture;
```
**代码**
创建 Ec2Client。
```
Ec2AsyncClient ec2AsyncClient = Ec2AsyncClient.builder()
.region(Region.US_EAST_1)
.build();
```
然后调用 describeAvailabilityZones () 并检索结果。
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2AsyncClient;
import software.amazon.awssdk.services.ec2.model.DescribeRegionsResponse;
import software.amazon.awssdk.services.ec2.model.DescribeAvailabilityZonesResponse;
import java.util.concurrent.CompletableFuture;
/**
* 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 DescribeRegionsAndZones {
public static void main(String[] args) {
Ec2AsyncClient ec2AsyncClient = Ec2AsyncClient.builder()
.region(Region.US_EAST_1)
.build();
try {
CompletableFuture future = describeEC2RegionsAndZonesAsync(ec2AsyncClient);
future.join(); // Wait for both async operations to complete.
} catch (RuntimeException rte) {
System.err.println("An exception occurred: " + (rte.getCause() != null ? rte.getCause().getMessage() : rte.getMessage()));
}
}
/**
* Asynchronously describes the EC2 regions and availability zones.
*
* @param ec2AsyncClient the EC2 async client used to make the API calls
* @return a {@link CompletableFuture} that completes when both the region and availability zone descriptions are complete
*/
public static CompletableFuture describeEC2RegionsAndZonesAsync(Ec2AsyncClient ec2AsyncClient) {
// Initiate the asynchronous request to describe regions
CompletableFuture regionsResponse = ec2AsyncClient.describeRegions();
// Handle the response or exception for regions
CompletableFuture regionsFuture = regionsResponse.whenComplete((regionsResp, ex) -> {
if (ex != null) {
// Handle the exception by throwing a RuntimeException
throw new RuntimeException("Failed to describe EC2 regions.", ex);
} else if (regionsResp == null || regionsResp.regions().isEmpty()) {
// Throw an exception if the response is null or the result is empty
throw new RuntimeException("No EC2 regions found.");
} else {
// Process the response if no exception occurred and the result is not empty
regionsResp.regions().forEach(region -> {
System.out.printf(
"Found Region %s with endpoint %s%n",
region.regionName(),
region.endpoint());
});
}
});
CompletableFuture zonesResponse = ec2AsyncClient.describeAvailabilityZones();
CompletableFuture zonesFuture = zonesResponse.whenComplete((zonesResp, ex) -> {
if (ex != null) {
throw new RuntimeException("Failed to describe EC2 availability zones.", ex);
} else if (zonesResp == null || zonesResp.availabilityZones().isEmpty()) {
throw new RuntimeException("No EC2 availability zones found.");
} else {
zonesResp.availabilityZones().forEach(zone -> {
System.out.printf(
"Found Availability Zone %s with status %s in region %s%n",
zone.zoneName(),
zone.state(),
zone.regionName()
);
});
}
});
return CompletableFuture.allOf(regionsFuture, zonesFuture);
}
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/7486a1a092aa8e16a21698ef26f9d524fef62e55/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeRegionsAndZones.java) GitHub。
## 描述账户
要列出有关您账户的 EC2相关信息，请调用 Ec2Client `describeAccountAttributes` 的方法。此方法返回一个 [DescribeAccountAttributesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeAccountAttributesResponse.html) 对象。调用此对象`accountAttributes`方法以获取[AccountAttribute](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AccountAttribute.html)对象列表。您可以遍历该列表来检索 `AccountAttribute` 对象。
您可以通过调用 `AccountAttribute` 对象的 `attributeValues` 方法来获取您账户的属性值。此方法返回[AccountAttributeValue](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AccountAttributeValue.html)对象列表。您可以遍历第二个列表来显示属性的值（请参阅以下代码示例）。
**导入**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2AsyncClient;
import software.amazon.awssdk.services.ec2.model.DescribeAccountAttributesResponse;
import java.util.concurrent.CompletableFuture;
```
**代码**
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2AsyncClient;
import software.amazon.awssdk.services.ec2.model.DescribeAccountAttributesResponse;
import java.util.concurrent.CompletableFuture;
/**
* 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 DescribeAccount {
public static void main(String[] args) {
Ec2AsyncClient ec2AsyncClient = Ec2AsyncClient.builder()
.region(Region.US_EAST_1)
.build();
try {
CompletableFuture future = describeEC2AccountAsync(ec2AsyncClient);
future.join();
System.out.println("EC2 Account attributes described successfully.");
} catch (RuntimeException rte) {
System.err.println("An exception occurred: " + (rte.getCause() != null ? rte.getCause().getMessage() : rte.getMessage()));
}
}
/**
* Describes the EC2 account attributes asynchronously.
*
* @param ec2AsyncClient the EC2 asynchronous client to use for the operation
* @return a {@link CompletableFuture} containing the {@link DescribeAccountAttributesResponse} with the account attributes
*/
public static CompletableFuture describeEC2AccountAsync(Ec2AsyncClient ec2AsyncClient) {
CompletableFuture response = ec2AsyncClient.describeAccountAttributes();
return response.whenComplete((accountResults, ex) -> {
if (ex != null) {
// Handle the exception by throwing a RuntimeException.
throw new RuntimeException("Failed to describe EC2 account attributes.", ex);
} else if (accountResults == null || accountResults.accountAttributes().isEmpty()) {
// Throw an exception if the response is null or no account attributes are found.
throw new RuntimeException("No account attributes found.");
} else {
// Process the response if no exception occurred.
accountResults.accountAttributes().forEach(attribute -> {
System.out.println("\nThe name of the attribute is " + attribute.attributeName());
attribute.attributeValues().forEach(
myValue -> System.out.println("The value of the attribute is " + myValue.attributeValue()));
});
}
});
}
}
```
请参阅上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/7486a1a092aa8e16a21698ef26f9d524fef62e55/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeAccount.java) GitHub。
## 更多信息
+ Linux 实例 Amazon EC2 用户指南中的@@ [区域和可用区](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/using-regions-availability-zones.html)
+ [DescribeRegions](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeRegions.html)在 Amazon EC2 API 参考中
+ [DescribeAvailabilityZones](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeAvailabilityZones.html)在 Amazon EC2 API 参考中
# 在 Amazon EC2 中使用安全组
## 创建安全组
要创建安全组，请使用包含密钥名称的 [CreateSecurityGroupRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/CreateSecurityGroupRequest.html) 调用 Ec2Client 的 `createSecurityGroup` 方法。
**导入**。
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.CreateSecurityGroupRequest;
import software.amazon.awssdk.services.ec2.model.AuthorizeSecurityGroupIngressRequest;
import software.amazon.awssdk.services.ec2.model.AuthorizeSecurityGroupIngressResponse;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
import software.amazon.awssdk.services.ec2.model.IpPermission;
import software.amazon.awssdk.services.ec2.model.CreateSecurityGroupResponse;
import software.amazon.awssdk.services.ec2.model.IpRange;
```
**代码**
```
CreateSecurityGroupRequest createRequest = CreateSecurityGroupRequest.builder()
.groupName(groupName)
.description(groupDesc)
.vpcId(vpcId)
.build();
CreateSecurityGroupResponse resp= ec2.createSecurityGroup(createRequest);
```
请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/CreateSecurityGroup.java)。
## 配置安全组
安全组可以控制对 Amazon EC2 实例的入站 (入口) 流量和出站 (出口) 流量。
要向安全组添加入口规则，请使用 Ec2Client 的 `authorizeSecurityGroupIngress` 方法，提供安全组的名称和您想要在 [AuthorizeSecurityGroupIngressRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AuthorizeSecurityGroupIngressRequest.html) 对象中分配给安全组的访问规则 ([IpPermission](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/IpPermission.html))。以下示例演示如何将 IP 权限添加到安全组。
**导入**。
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.CreateSecurityGroupRequest;
import software.amazon.awssdk.services.ec2.model.AuthorizeSecurityGroupIngressRequest;
import software.amazon.awssdk.services.ec2.model.AuthorizeSecurityGroupIngressResponse;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
import software.amazon.awssdk.services.ec2.model.IpPermission;
import software.amazon.awssdk.services.ec2.model.CreateSecurityGroupResponse;
import software.amazon.awssdk.services.ec2.model.IpRange;
```
**代码**
首先，创建一个 Ec2Client
```
Region region = Region.US_WEST_2;
Ec2Client ec2 = Ec2Client.builder()
.region(region)
.build();
```
然后使用 Ec2Client 的 `authorizeSecurityGroupIngress` 方法，
```
IpRange ipRange = IpRange.builder()
.cidrIp("0.0.0.0/0").build();
IpPermission ipPerm = IpPermission.builder()
.ipProtocol("tcp")
.toPort(80)
.fromPort(80)
.ipRanges(ipRange)
.build();
IpPermission ipPerm2 = IpPermission.builder()
.ipProtocol("tcp")
.toPort(22)
.fromPort(22)
.ipRanges(ipRange)
.build();
AuthorizeSecurityGroupIngressRequest authRequest =
AuthorizeSecurityGroupIngressRequest.builder()
.groupName(groupName)
.ipPermissions(ipPerm, ipPerm2)
.build();
AuthorizeSecurityGroupIngressResponse authResponse =
ec2.authorizeSecurityGroupIngress(authRequest);
System.out.printf(
"Successfully added ingress policy to Security Group %s",
groupName);
return resp.groupId();
} catch (Ec2Exception e) {
System.err.println(e.awsErrorDetails().errorMessage());
System.exit(1);
}
return "";
}
```
要向安全组添加出口规则，请在 [AuthorizeSecurityGroupEgressRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AuthorizeSecurityGroupEgressRequest.html) 中向 Ec2Client 的 `authorizeSecurityGroupEgress` 方法提供相似的数据。
请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/CreateSecurityGroup.java)。
## 描述安全组
要描述您的安全组或获取相关信息，请调用 Ec2Client 的 `describeSecurityGroups` 方法。该方法返回 [DescribeSecurityGroupsResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeSecurityGroupsResponse.html)，使用它后，您可以通过调用其 `securityGroups` 方法（返回一个 [SecurityGroup](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/SecurityGroup.html) 对象的列表）来访问安全组的列表。
**导入**。
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.DescribeSecurityGroupsRequest;
import software.amazon.awssdk.services.ec2.model.DescribeSecurityGroupsResponse;
import software.amazon.awssdk.services.ec2.model.SecurityGroup;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
```
**代码**
```
public static void describeEC2SecurityGroups(Ec2Client ec2, String groupId) {
try {
DescribeSecurityGroupsRequest request =
DescribeSecurityGroupsRequest.builder()
.groupIds(groupId).build();
DescribeSecurityGroupsResponse response =
ec2.describeSecurityGroups(request);
for(SecurityGroup group : response.securityGroups()) {
System.out.printf(
"Found Security Group with id %s, " +
"vpc id %s " +
"and description %s",
group.groupId(),
group.vpcId(),
group.description());
}
} catch (Ec2Exception e) {
System.err.println(e.awsErrorDetails().errorMessage());
System.exit(1);
}
}
```
请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeSecurityGroups.java)。
## 删除安全组
要删除安全组，请调用 Ec2Client 的 `deleteSecurityGroup` 方法，将其传递给一个包含要删除安全组 ID 的 [DeleteSecurityGroupRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DeleteSecurityGroupRequest.html)。
**导入**。
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.ec2.Ec2Client;
import software.amazon.awssdk.services.ec2.model.DeleteSecurityGroupRequest;
import software.amazon.awssdk.services.ec2.model.Ec2Exception;
```
**代码**
```
public static void deleteEC2SecGroup(Ec2Client ec2,String groupId) {
try {
DeleteSecurityGroupRequest request = DeleteSecurityGroupRequest.builder()
.groupId(groupId)
.build();
ec2.deleteSecurityGroup(request);
System.out.printf(
"Successfully deleted Security Group with id %s", groupId);
} catch (Ec2Exception e) {
System.err.println(e.awsErrorDetails().errorMessage());
System.exit(1);
}
}
```
请参阅 GitHub 上的[完整示例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/DeleteSecurityGroup.java)。
## 更多信息
+ 《Amazon EC2 用户指南（适用于 Linux 实例）》中的 [Amazon EC2 安全组](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-security-groups.html)
+ 《Amazon EC2 用户指南（适用于 Linux 实例）》中的[为您的 Linux 实例授权入站流量](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/authorizing-access-to-an-instance.html)
+ 《Amazon EC2 API Reference》中的 [CreateSecurityGroup](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_CreateSecurityGroup.html)
+ 《Amazon EC2 API Reference》中的 [DescribeSecurityGroups](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeSecurityGroups.html)
+ 《Amazon EC2 API Reference》中的 [DeleteSecurityGroup](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DeleteSecurityGroup.html)
+ 《Amazon EC2 API Reference》中的 [AuthorizeSecurityGroupIngress](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_AuthorizeSecurityGroupIngress.html)
# 使用 Amazon EC2 实例元数据
适用于 Amazon EC2 实例元数据服务的 Java SDK 客户端（元数据客户端）允许您的应用程序访问其本地 EC2 实例上的元数据。元数据客户端使用本地实例 [IMDSv2](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-service.html)（实例元数据服务 v2），并使用面向会话的请求。
SDK 中有两个客户端类可用。同步 `[Ec2MetadataClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/imds/Ec2MetadataClient.html)` 用于阻塞操作，[https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/imds/Ec2MetadataAsyncClient.html](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/imds/Ec2MetadataAsyncClient.html) 用于异步、非阻塞用例。
## 开始使用
要使用元数据客户端，请将 `imds` Maven 构件添加到您的项目中。您还需要在类路径上具有 `[SdkHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/SdkHttpClient.html)` 的类，或对于异步变体而言，具有 `[SdkAsyncHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/async/SdkAsyncHttpClient.html)` 的类。
以下 Maven XML 显示了使用同步的依赖关系片段[UrlConnectionHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/urlconnection/UrlConnectionHttpClient.html)以及元数据客户端的依赖关系。
```
software.amazon.awssdk
bom
VERSION
pom
import
software.amazon.awssdk
imds
software.amazon.awssdk
url-connection-client
```
在 [Maven Central 存储库](https://central.sonatype.com/artifact/software.amazon.awssdk/bom)中搜索 `bom` 构件的最新版本。
要使用异步 HTTP 客户端，请替换 `url-connection-client` 构件的依赖项片段。例如，以下代码段引入了[NettyNioAsyncHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/nio/netty/NettyNioAsyncHttpClient.html)实现。
```
software.amazon.awssdk
netty-nio-client
```
## 使用元数据客户端
### 实例化元数据客户端
当类路径上只有一个 `SdkHttpClient` 接口的实现时，您可以实例化同步 `Ec2MetadataClient` 的实例。为此，请调用 static `Ec2MetadataClient#create()` 方法，如以下代码段所示。
```
Ec2MetadataClient client = Ec2MetadataClient.create(); // 'Ec2MetadataAsyncClient#create' is the asynchronous version.
```
如果您的应用程序有多个 `SdkHttpClient` 或 `SdkHttpAsyncClient` 接口的实现，则必须指定一个实现以供元数据客户端使用，如[可配置 HTTP 客户端](#examples-ec2-IMDS-features-http)部分所示。
**注意**
对于大多数服务客户端（例如 Amazon S3），适用于 Java 的 SDK 会自动添加 `SdkHttpClient` 或 `SdkHttpAsyncClient` 接口的实现。如果您的元数据客户端使用相同的实现，则 `Ec2MetadataClient#create()` 将起作用。如果您需要不同的实现，则必须在创建元数据客户端时指定它。
### 发送请求
要检索实例元数据，请实例化 `EC2MetadataClient` 类，然后使用指定[实例元数据类别](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html)的路径参数调用 `get` 方法。
以下示例将与 `ami-id` 键关联的值打印到控制台。
```
Ec2MetadataClient client = Ec2MetadataClient.create();
Ec2MetadataResponse response = client.get("/latest/meta-data/ami-id");
System.out.println(response.asString());
client.close(); // Closes the internal resources used by the Ec2MetadataClient class.
```
如果路径无效，则 `get` 方法将引发异常。
请对多个请求重复使用同一个客户端实例，但当不再需要该客户端时，请在该客户端上调用 `close` 来释放资源。调用 close 方法后，将无法再使用客户端实例。
### 解析响应
EC2 实例元数据可以以不同的格式输出。纯文本和 JSON 是最常用的格式。元数据客户端提供了使用这些格式的方法。
如以下示例所示，使用 `asString` 方法以 Java 字符串的形式获取数据。您还可以使用 `asList` 方法来分隔返回多行的纯文本响应。
```
Ec2MetadataClient client = Ec2MetadataClient.create();
Ec2MetadataResponse response = client.get("/latest/meta-data/");
String fullResponse = response.asString();
List splits = response.asList();
```
如果响应采用 JSON 格式，请使用 `Ec2MetadataResponse#asDocument` 方法将 JSON 响应解析为 [Document](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/core/document/Document.html) 实例，如以下代码段所示。
```
Document fullResponse = response.asDocument();
```
如果元数据的格式不是 JSON，则会引发异常。如果成功解析了响应，则可以使用 [document API](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/core/document/package-summary.html) 来更详细地检查响应。请查阅实例[元数据类别表](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html)，了解哪些元数据类别提供了 JSON 格式的响应。
## 配置元数据客户端
### 重试
您可以为元数据客户端配置重试机制。如果这样做，则客户端可以自动重试因意外原因而失败的请求。默认情况下，客户端对失败的请求重试三次，两次尝试之间的时间呈指数回退。
如果您的用例需要不同的重试机制，则可以使用其客户端生成器上的 `retryPolicy` 方法自定义客户端。例如，以下示例将同步客户端配置为共五次重试，每两次重试之间固定延迟两秒钟。
```
BackoffStrategy fixedBackoffStrategy = FixedDelayBackoffStrategy.create(Duration.ofSeconds(2));
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.retryPolicy(retryPolicyBuilder -> retryPolicyBuilder.numRetries(5)
.backoffStrategy(fixedBackoffStrategy))
.build();
```
有几种[BackoffStrategies](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/core/retry/backoff/package-summary.html)可以与元数据客户端一起使用。
您也可以完全禁用重试机制，如以下代码段所示。
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.retryPolicy(Ec2MetadataRetryPolicy.none())
.build();
```
使用 `Ec2MetadataRetryPolicy#none()` 会禁用默认的重试策略，因此元数据客户端不尝试重试。
### IP 版本
默认情况下，元数据客户端使用的 IPV4 终端节点`http://169.254.169.254`。要将客户端更改为使用 IPV6 版本，请使用构建器的`endpointMode`或`endpoint`方法。如果在生成器上同时调用这两个方法，则会出现异常。
以下示例显示了这两个 IPV6 选项。
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.endpointMode(EndpointMode.IPV6)
.build();
```
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.endpoint(URI.create("http://[fd00:ec2::254]"))
.build();
```
## 主要 功能
### 异步客户端
要使用非阻塞版本的客户端，请实例化 `Ec2MetadataAsyncClient` 类的实例。以下示例中的代码使用默认设置创建异步客户端，并使用 `get` 方法检索 `ami-id` 键的值。
```
Ec2MetadataAsyncClient asyncClient = Ec2MetadataAsyncClient.create();
CompletableFuture response = asyncClient.get("/latest/meta-data/ami-id");
```
当响应返回时，`get` 方法返回的 `java.util.concurrent.CompletableFuture` 就完成了。以下示例将 `ami-id` 元数据打印到控制台。
```
response.thenAccept(metadata -> System.out.println(metadata.asString()));
```
### 可配置 HTTP 客户端
每个元数据客户端的生成器都有一种可用于提供自定义 HTTP 客户端的 `httpClient` 方法。
以下示例显示了自定义 `UrlConnectionHttpClient` 实例的代码。
```
SdkHttpClient httpClient =
UrlConnectionHttpClient.builder()
.socketTimeout(Duration.ofMinutes(5))
.proxyConfiguration(proxy -> proxy.endpoint(URI.create("http://proxy.example.net:8888"))))
.build();
Ec2MetadataClient metaDataClient =
Ec2MetadataClient.builder()
.httpClient(httpClient)
.build();
// Use the metaDataClient instance.
metaDataClient.close(); // Close the instance when no longer needed.
```
以下示例显示了带有异步元数据客户端的自定义 `NettyNioAsyncHttpClient` 实例的代码。
```
SdkAsyncHttpClient httpAsyncClient =
NettyNioAsyncHttpClient.builder()
.connectionTimeout(Duration.ofMinutes(5))
.maxConcurrency(100)
.build();
Ec2MetadataAsyncClient asyncMetaDataClient =
Ec2MetadataAsyncClient.builder()
.httpClient(httpAsyncClient)
.build();
// Use the asyncMetaDataClient instance.
asyncMetaDataClient.close(); // Close the instance when no longer needed.
```
本指南中的 [在中配置 HTTP 客户端 AWS SDK for Java 2.x](http-configuration.md) 主题详细介绍了如何配置适用于 Java 的 SDK 中可用的 HTTP 客户端。
### 令牌缓存
由于客户端使用元数据 IMDSv2，因此所有请求都与会话关联。会话由带过期时间的令牌定义，元数据客户端会为您管理该令牌。每个元数据请求都会自动重复使用令牌，直到令牌过期。
默认情况下，令牌持续六小时（21600 秒）。除非您的特定用例需要高级配置，否则我们建议您保留默认 time-to-live值。
如果需要，可使用 `tokenTtl` 生成器方法配置持续时间。例如，以下代码段中的代码创建了一个会话持续时间为五分钟的客户端。
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.tokenTtl(Duration.ofMinutes(5))
.build();
```
如果您省略调用生成器上的 `tokenTtl` 方法，则改用默认持续时间 21,600。