本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。
# 使用 Amazon EC2
本節提供[Amazon EC2](https://docs.aws.amazon.com/ec2/)使用 適用於 Java 的 AWS SDK 2.x 的程式設計範例。
**Topics**
+ [管理 Amazon EC2 執行個體](examples-ec2-instances.md)
+ [使用 AWS 區域 和可用區域](examples-ec2-regions-zones.md)
+ [在 中使用安全群組 Amazon EC2](examples-ec2-security-groups.md)
+ [使用 Amazon EC2 執行個體中繼資料](examples-ec2-IMDS.md)
# 管理 Amazon EC2 執行個體
## 建立 執行個體
透過呼叫 [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))方法建立新的 Amazon EC2 執行個體，提供 [RunInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/RunInstancesRequest.html)，其中包含要使用的 [Amazon Machine Image (AMI)](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/AMIs.html) 和[執行個體類型](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/instance-types.html)。
**匯入**
```
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;
```
**Code**
```
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 "";
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/CreateInstance.java)。
## 啟動執行個體
若要啟動 Amazon EC2 執行個體，請呼叫 Ec2Client 的 [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))方法，為其提供 [StartInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/StartInstancesRequest.html)，其中包含要啟動的執行個體 ID。
**匯入**
```
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;
```
**Code**
```
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);
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/StartStopInstance.java)。
## 停止執行個體
若要停止 Amazon EC2 執行個體，請呼叫 Ec2Client 的 [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))方法，為其提供 [StopInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/StopInstancesRequest.html)，其中包含要停止的執行個體 ID。
**匯入**
```
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;
```
**Code**
```
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);
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/StartStopInstance.java)。
## 重新啟動執行個體
若要重新啟動 Amazon EC2 執行個體，請呼叫 Ec2Client 的 [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))方法，為其提供 [RebootInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/RebootInstancesRequest.html)，其中包含要重新啟動的執行個體 ID。
**匯入**
```
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;
```
**Code**
```
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);
}
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/RebootInstance.java)。
## 描述執行個體
若要列出您的執行個體，請建立 [DescribeInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeInstancesRequest.html) 並呼叫 Ec2Client 的 [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))方法。它會傳回 [DescribeInstancesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeInstancesResponse.html) 物件，您可以用來列出您帳戶和區域的 Amazon EC2 執行個體。
執行個體依照*保留*分組。每個保留對應到呼叫 `startInstances`，用以啟動執行個體。若要列出您的執行個體，您必須先呼叫 `DescribeInstancesResponse` 類別的 `reservations` 方法，然後在每個傳回的 `instances`Reservation[ 物件上呼叫 ](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/Reservation.html)。
**匯入**
```
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;
```
**Code**
```
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);
}
}
```
結果會分頁；您可以將結果物件的 `nextToken` 方法所傳回的值傳遞給新請求物件的 `nextToken` 方法，然後在下一次呼叫 `describeInstances` 時使用新的請求物件，以取得進一步結果。
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeInstances.java)。
## 監控執行個體
您可以監控 Amazon EC2 執行個體的各個層面，例如 CPU 和網路使用率、可用的記憶體，以及剩餘的磁碟空間。若要進一步了解執行個體監控，請參閱《Linux 執行個體 Amazon EC2 使用者指南》中的[監控 Amazon EC2](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/monitoring_ec2.html)。
若要開始監控執行個體，您必須使用要監控的執行個體 ID 建立 [MonitorInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/MonitorInstancesRequest.html)，並將其傳遞至 Ec2Client 的 [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))方法。
**匯入**
```
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;
```
**Code**
```
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);
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/MonitorInstance.java)。
## 停止監控執行個體
若要停止監控執行個體，請使用執行個體的 ID 建立 [UnmonitorInstancesRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/UnmonitorInstancesRequest.html) 以停止監控，並將其傳遞至 Ec2Client 的 [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))方法。
**匯入**
```
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;
```
**Code**
```
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);
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/ac748d8ef99cd17e297cb74fe13aa671e2679088/javav2/example_code/ec2/src/main/java/com/example/ec2/MonitorInstance.java)。
## 其他資訊
+ Amazon EC2 API 參考中的 [RunInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_RunInstances.html)
+ Amazon EC2 API 參考中的 [DescribeInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstances.html)
+ Amazon EC2 API 參考中的 [StartInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_StartInstances.html)
+ Amazon EC2 API 參考中的 [StopInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_StopInstances.html)
+ API Amazon EC2 參考中的 [RebootInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_RebootInstances.html)
+ Amazon EC2 API 參考中的 [MonitorInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_MonitorInstances.html)
+ Amazon EC2 API 參考中的 [UnmonitorInstances](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_UnmonitorInstances.html)
# 使用 AWS 區域 和可用區域
## 描述區域
若要列出您的帳戶可用的區域，請呼叫 Ec2Client 的 `describeRegions`方法。它會傳回 [DescribeRegionsResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeRegionsResponse.html)。呼叫傳回物件的 `regions` 方法以取得代表每個區域的 [Region](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/Region.html) 物件清單。
**匯入**
```
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;
```
**Code**
```
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);
}
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/7486a1a092aa8e16a21698ef26f9d524fef62e55/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeRegionsAndZones.java)。
## 描述可用區域
若要列出您帳戶可用的每個可用區域，請呼叫 Ec2Client 的 `describeAvailabilityZones`方法。它會傳回 [DescribeAvailabilityZonesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeAvailabilityZonesResponse.html)。呼叫其 `availabilityZones` 方法以取得代表每個可用區域的 [AvailabilityZone](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AvailabilityZone.html) 物件清單。
**匯入**
```
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;
```
**Code**
建立 Ec2Client。
```
Ec2AsyncClient ec2AsyncClient = Ec2AsyncClient.builder()
.region(Region.US_EAST_1)
.build();
```
然後呼叫 describeAvailabilityZones () 並擷取結果。
```
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);
}
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/7486a1a092aa8e16a21698ef26f9d524fef62e55/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeRegionsAndZones.java)。
## 描述帳戶
若要列出您帳戶的 EC2-related，請呼叫 Ec2Client 的 `describeAccountAttributes`方法。此方法會傳回一個 [DescribeAccountAttributesResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeAccountAttributesResponse.html) 物件。叫用此物件的 `accountAttributes` 方法來取得 [AccountAttribute](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AccountAttribute.html) 物件的清單。您可以逐一查看清單以擷取`AccountAttribute`物件。
您可以透過叫用`AccountAttribute`物件的 `attributeValues`方法，取得您帳戶的屬性值。此方法會傳回 [AccountAttributeValue](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AccountAttributeValue.html) 物件的清單。您可以逐一查看第二個清單以顯示屬性值 (請參閱下列程式碼範例)。
**匯入**
```
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;
```
**Code**
```
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()));
});
}
});
}
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/7486a1a092aa8e16a21698ef26f9d524fef62e55/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeAccount.java)。
## 其他資訊
+ Linux 執行個體 Amazon EC2 使用者指南中的[區域和可用區域](https://docs.aws.amazon.com//AWSEC2/latest/UserGuide/using-regions-availability-zones.html)
+ Amazon EC2 API 參考中的 [DescribeRegions](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeRegions.html)
+ Amazon EC2 API 參考中的 [DescribeAvailabilityZones](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeAvailabilityZones.html)
# 在 中使用安全群組 Amazon EC2
## 建立安全群組
若要建立安全群組，請使用包含金鑰名稱的 [CreateSecurityGroupRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/CreateSecurityGroupRequest.html) 呼叫 Ec2Client 的 `createSecurityGroup`方法。
**匯入**
```
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;
```
**Code**
```
CreateSecurityGroupRequest createRequest = CreateSecurityGroupRequest.builder()
.groupName(groupName)
.description(groupDesc)
.vpcId(vpcId)
.build();
CreateSecurityGroupResponse resp= ec2.createSecurityGroup(createRequest);
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/CreateSecurityGroup.java)。
## 設定安全群組
安全群組可以控制執行個體的傳入 （傳入） 和傳出 （傳出） 流量 Amazon EC2 。
若要將輸入規則新增至您的安全群組，請使用 Ec2Client 的 `authorizeSecurityGroupIngress`方法，提供安全群組的名稱，以及您想要在 [AuthorizeSecurityGroupIngressRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AuthorizeSecurityGroupIngressRequest.html) 物件中為其指派的存取規則 ([IpPermission](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/IpPermission.html))。以下範例說明如何將 IP 許可新增至安全群組。
**匯入**
```
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;
```
**Code**
首先，建立 Ec2Client
```
Region region = Region.US_WEST_2;
Ec2Client ec2 = Ec2Client.builder()
.region(region)
.build();
```
然後使用 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 "";
}
```
若要將輸出規則新增至安全群組，請在 [AuthorizeSecurityGroupEgressRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/AuthorizeSecurityGroupEgressRequest.html) 中提供類似的資料給 Ec2Client 的 `authorizeSecurityGroupEgress`方法。
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/CreateSecurityGroup.java)。
## 描述安全群組
若要描述您的安全群組或取得相關資訊，請呼叫 Ec2Client 的 `describeSecurityGroups`方法。它會傳回 [DescribeSecurityGroupsResponse](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DescribeSecurityGroupsResponse.html)，您可透過呼叫它的 `securityGroups` 方法 (此方法會傳回 [SecurityGroup](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/SecurityGroup.html) 物件清單)，來存取安全群組的清單。
**匯入**
```
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;
```
**Code**
```
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);
}
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/DescribeSecurityGroups.java)。
## 刪除安全群組
若要刪除安全群組，請呼叫 Ec2Client 的 `deleteSecurityGroup`方法，並向其傳遞 [DeleteSecurityGroupRequest](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/ec2/model/DeleteSecurityGroupRequest.html)，其中包含要刪除的安全群組 ID。
**匯入**
```
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;
```
**Code**
```
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);
}
}
```
請參閱 GitHub 上的[完整範例](https://github.com/awsdocs/aws-doc-sdk-examples/blob/0b1785e42949ebf959eaa0f0da4dc2a48f92ea25/javav2/example_code/ec2/src/main/java/com/example/ec2/DeleteSecurityGroup.java)。
## 其他資訊
+ Linux 執行個體 Amazon EC2 使用者指南中的[Amazon EC2 安全群組](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-security-groups.html)
+ 《[Linux 執行個體使用者指南》中的授權 Linux 執行個體的傳入流量](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/authorizing-access-to-an-instance.html) Amazon EC2
+ Amazon EC2 API 參考中的 [CreateSecurityGroup](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_CreateSecurityGroup.html)
+ Amazon EC2 API 參考中的 [DescribeSecurityGroups](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeSecurityGroups.html)
+ Amazon EC2 API 參考中的 [DeleteSecurityGroup](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DeleteSecurityGroup.html)
+ Amazon EC2 API 參考中的 [AuthorizeSecurityGroupIngress](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_AuthorizeSecurityGroupIngress.html)
# 使用 Amazon EC2 執行個體中繼資料
Amazon EC2 執行個體中繼資料服務的 Java SDK 用戶端 （中繼資料用戶端） 可讓您的應用程式存取其本機 EC2 執行個體上的中繼資料。中繼資料用戶端使用 [IMDSv2](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-service.html) (Instance Metadata Service v2) 的本機執行個體，並使用工作階段導向請求。
開發套件提供兩種用戶端類別。同步`[Ec2MetadataClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/imds/Ec2MetadataClient.html)`用於封鎖操作，而 [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)用於非同步、非封鎖的使用案例。
## 開始使用
若要使用中繼資料用戶端，請將 `imds` Maven 成品新增至您的專案。您也需要 classpath 上 `[SdkHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/SdkHttpClient.html)`（或非同步變體`[SdkAsyncHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/async/SdkAsyncHttpClient.html)`的 ) 的類別。
下列 Maven XML 顯示使用同步 [UrlConnectionHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/urlconnection/UrlConnectionHttpClient.html) 以及中繼資料用戶端相依性的相依性程式碼片段。
```
software.amazon.awssdk
bom
VERSION
pom
import
software.amazon.awssdk
imds
software.amazon.awssdk
url-connection-client
```
搜尋 [Maven 中央儲存庫](https://central.sonatype.com/artifact/software.amazon.awssdk/bom)以取得最新版本的`bom`成品。
若要使用非同步 HTTP 用戶端，請取代`url-connection-client`成品的相依性程式碼片段。例如，以下程式碼片段引入 [NettyNioAsyncHttpClient](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/http/nio/netty/NettyNioAsyncHttpClient.html) 實作。
```
software.amazon.awssdk
netty-nio-client
```
## 使用中繼資料用戶端
### 執行個體化中繼資料用戶端
當 classpath 上只有一個`SdkHttpClient`介面實作`Ec2MetadataClient`時，您可以執行個體化同步的執行個體。若要這麼做，請呼叫靜態`Ec2MetadataClient#create()`方法，如下列程式碼片段所示。
```
Ec2MetadataClient client = Ec2MetadataClient.create(); // 'Ec2MetadataAsyncClient#create' is the asynchronous version.
```
如果您的應用程式有多個 `SdkHttpClient`或 `SdkHttpAsyncClient` 介面實作，您必須指定中繼資料用戶端要使用的實作，如 [可設定的 HTTP 用戶端](#examples-ec2-IMDS-features-http)一節所示。
**注意**
對於大多數服務用戶端，例如 Amazon S3，適用於 Java 的 SDK 會自動新增 `SdkHttpClient`或 `SdkHttpAsyncClient` 介面的實作。如果您的中繼資料用戶端使用相同的實作，則 `Ec2MetadataClient#create()`會運作。如果您需要不同的實作，您必須在建立中繼資料用戶端時指定它。
### 傳送請求
若要擷取執行個體中繼資料，請執行個體化 `EC2MetadataClient`類別，並使用指定[執行個體中繼資料類別](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html)的路徑參數呼叫 `get` 方法。
下列範例會將與 `ami-id`金鑰相關聯的值列印至 主控台。
```
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.
```
如果路徑無效，`get`方法會擲回例外狀況。
針對多個請求重複使用相同的用戶端執行個體，但在不再需要釋放資源時，在用戶端`close`上呼叫 。呼叫關閉方法之後，就無法再使用用戶端執行個體。
### 剖析回應
EC2 執行個體中繼資料可以以不同的格式輸出。純文字和 JSON 是最常用的格式。中繼資料用戶端提供使用這些格式的方法。
如下列範例所示，使用 `asString`方法取得資料做為 Java 字串。您也可以使用 `asList`方法來分隔傳回多行的純文字回應。
```
Ec2MetadataClient client = Ec2MetadataClient.create();
Ec2MetadataResponse response = client.get("/latest/meta-data/");
String fullResponse = response.asString();
List splits = response.asList();
```
如果回應為 JSON，請使用 `Ec2MetadataResponse#asDocument`方法將 JSON 回應剖析為[文件](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/core/document/Document.html)執行個體，如下列程式碼片段所示。
```
Document fullResponse = response.asDocument();
```
如果中繼資料的格式不是 JSON，則會擲回例外狀況。如果成功剖析回應，您可以使用 [文件 API](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/core/document/package-summary.html) 來更詳細地檢查回應。請參閱執行個體[中繼資料類別圖表](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html)，以了解哪些中繼資料類別提供 JSON 格式的回應。
## 設定中繼資料用戶端
### 重試
您可以使用重試機制設定中繼資料用戶端。如果您這麼做，則用戶端可以自動重試因意外原因失敗的請求。根據預設，用戶端會在失敗的請求上重試三次，並在嘗試之間有指數退避時間。
如果您的使用案例需要不同的重試機制，您可以在其建置器上使用 `retryPolicy`方法自訂用戶端。例如，下列範例顯示同步用戶端，其設定在嘗試與五次重試嘗試之間的固定延遲為兩秒。
```
BackoffStrategy fixedBackoffStrategy = FixedDelayBackoffStrategy.create(Duration.ofSeconds(2));
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.retryPolicy(retryPolicyBuilder -> retryPolicyBuilder.numRetries(5)
.backoffStrategy(fixedBackoffStrategy))
.build();
```
您可以搭配中繼資料用戶端使用數個 [BackoffStrategies](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/core/retry/backoff/package-summary.html)。
您也可以完全停用重試機制，如下列程式碼片段所示。
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.retryPolicy(Ec2MetadataRetryPolicy.none())
.build();
```
使用 會`Ec2MetadataRetryPolicy#none()`停用預設重試政策，讓中繼資料用戶端不會重試。
### IP 版本
根據預設，中繼資料用戶端會使用位於 的 IPV4 端點`http://169.254.169.254`。若要將用戶端變更為使用 IPV6 版本，請使用建置器的 `endpointMode`或 `endpoint`方法。如果在建置器上呼叫這兩種方法，就會產生例外狀況。
下列範例顯示兩個 IPV6 選項。
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.endpointMode(EndpointMode.IPV6)
.build();
```
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.endpoint(URI.create("http://[fd00:ec2::254]"))
.build();
```
## 主要功能
### 非同步用戶端
若要使用用戶端的非封鎖版本，請執行個體化 `Ec2MetadataAsyncClient`類別的執行個體。下列範例中的程式碼會建立具有預設設定的非同步用戶端，並使用 `get`方法擷取`ami-id`金鑰的值。
```
Ec2MetadataAsyncClient asyncClient = Ec2MetadataAsyncClient.create();
CompletableFuture response = asyncClient.get("/latest/meta-data/ami-id");
```
`get` 方法`java.util.concurrent.CompletableFuture`傳回的 會在回應傳回時完成。下列範例會將`ami-id`中繼資料列印到 主控台。
```
response.thenAccept(metadata -> System.out.println(metadata.asString()));
```
### 可設定的 HTTP 用戶端
每個中繼資料用戶端的建置器都有一種`httpClient`方法，您可以用來提供自訂的 HTTP 用戶端。
下列範例顯示自訂`UrlConnectionHttpClient`執行個體的程式碼。
```
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.
```
下列範例顯示具有非同步中繼資料用戶端之自訂`NettyNioAsyncHttpClient`執行個體的程式碼。
```
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 中設定 HTTP 用戶端 AWS SDK for Java 2.x](http-configuration.md)主題提供如何設定適用於 Java 的 開發套件中可用 HTTP 用戶端的詳細資訊。
### 權杖快取
由於中繼資料用戶端使用 IMDSv2，所有請求都會與工作階段相關聯。工作階段是由具有過期的字符定義，中繼資料用戶端會為您管理。每個中繼資料請求都會自動重複使用字符，直到過期為止。
根據預設，字符會持續六個小時 (21，600 秒）。建議您保留預設time-to-live值，除非您的特定使用案例需要進階組態。
如有需要，請使用`tokenTtl`建置器方法來設定持續時間。例如，以下程式碼片段中的程式碼會建立工作階段持續時間為五分鐘的用戶端。
```
Ec2MetadataClient client =
Ec2MetadataClient.builder()
.tokenTtl(Duration.ofMinutes(5))
.build();
```
如果您省略在建置器上呼叫 `tokenTtl`方法，則會改用預設持續時間 21，600。