背景

您在阿里云云服务器ECS的选型过程中，可以参考选型最佳实践，其中对比实例性能时，可以调用DescribeInstanceTypes API获取最新的规格性能参数。

当前ECS实例规格数量越来越多，为保证查询时可以获得符合条件的所有规格，及避免调用时触发限流，强烈推荐您使用分页查询的方式调用。

关于DescribeInstanceTypes API的接口文档可以参考DescribeInstanceTypes。

推荐方式

• 采用分页查询：查询非首页时，将上页返回的 NextToken值作为请求参数
• 设置 MaxResults以限制返回信息的条目数，推荐设置 MaxResults为 100及以下（当前最大为1600，后续最大值将只支持100）
• 尽可能指定过滤条件，如设置 InstanceTypeFamily指定实例规格所属的实例规格族，或设置 InstanceTypes指定查询的实例规格。

示例代码

需求举例：查询期望最小vCPU内核的数目为4，期望最小内存为8GiB的规格，示例代码中进行了分页查询，每次查询的MaxResults设置为100，并将查询结果进行整合。

package com.example.demo;


import com.aliyun.auth.credentials.Credential;
import com.aliyun.auth.credentials.provider.StaticCredentialProvider;
import com.aliyun.core.http.HttpClient;
import com.aliyun.core.http.HttpMethod;
import com.aliyun.core.http.ProxyOptions;
import com.aliyun.httpcomponent.httpclient.ApacheAsyncHttpClientBuilder;
import com.aliyun.sdk.service.ecs20140526.models.*;
import com.aliyun.sdk.service.ecs20140526.*;
import com.google.gson.Gson;
import darabonba.core.RequestConfiguration;
import darabonba.core.client.ClientOverrideConfiguration;
import darabonba.core.utils.CommonUtil;
import darabonba.core.TeaPair;
import org.apache.commons.lang3.StringUtils;

//import javax.net.ssl.KeyManager;
//import javax.net.ssl.X509TrustManager;
import java.net.InetSocketAddress;
import java.time.Duration;
import java.util.*;
import java.util.concurrent.CompletableFuture;

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

        // HttpClient Configuration
        /*HttpClient httpClient = new ApacheAsyncHttpClientBuilder()
                .connectionTimeout(Duration.ofSeconds(10)) // Set the connection timeout time, the default is 10 seconds
                .responseTimeout(Duration.ofSeconds(10)) // Set the response timeout time, the default is 20 seconds
                .maxConnections(128) // Set the connection pool size
                .maxIdleTimeOut(Duration.ofSeconds(50)) // Set the connection pool timeout, the default is 30 seconds
                // Configure the proxy
                .proxy(new ProxyOptions(ProxyOptions.Type.HTTP, new InetSocketAddress("<your-proxy-hostname>", 9001))
                        .setCredentials("<your-proxy-username>", "<your-proxy-password>"))
                // If it is an https connection, you need to configure the certificate, or ignore the certificate(.ignoreSSL(true))
                .x509TrustManagers(new X509TrustManager[]{})
                .keyManagers(new KeyManager[]{})
                .ignoreSSL(false)
                .build();*/

        // Configure Credentials authentication information, including ak, secret, token
        StaticCredentialProvider provider = StaticCredentialProvider.create(Credential.builder()
                .accessKeyId("<your-accessKeyId>")
                .accessKeySecret("<your-accessKeySecret>")
                //.securityToken("<your-token>") // use STS token
                .build());

        // Configure the Client
        AsyncClient client = AsyncClient.builder()
                .region("cn-zhangjiakou") // Region ID
                //.httpClient(httpClient) // Use the configured HttpClient, otherwise use the default HttpClient (Apache HttpClient)
                .credentialsProvider(provider)
                //.serviceConfiguration(Configuration.create()) // Service-level configuration
                // Client-level configuration rewrite, can set Endpoint, Http request parameters, etc.
                .overrideConfiguration(
                        ClientOverrideConfiguration.create()
                                .setEndpointOverride("ecs.cn-zhangjiakou.aliyuncs.com")
                        //.setReadTimeout(Duration.ofSeconds(30))
                )
                .build();

        List<DescribeInstanceTypesResponseBody.InstanceType> results = new ArrayList<>();
        // Parameter settings for API request
        DescribeInstanceTypesRequest describeInstanceTypesRequest = DescribeInstanceTypesRequest.builder()
                .minimumCpuCoreCount(4)
                .minimumMemorySize(8F)
                .maxResults(100L)
                // Request-level configuration rewrite, can set Http request parameters, etc.
                // .requestConfiguration(RequestConfiguration.create().setHttpHeaders(new HttpHeaders()))
                .build();
        
        List<DescribeInstanceTypesResponseBody.InstanceType> results = new ArrayList<>();
        // Parameter settings for API request
        DescribeInstanceTypesRequest describeInstanceTypesRequest;
        // Asynchronously get the return value of the API request
        CompletableFuture<DescribeInstanceTypesResponse> response;
        // Synchronously get the return value of the API request
        DescribeInstanceTypesResponse resp;
        String nextToken = null;
        do {
            describeInstanceTypesRequest = DescribeInstanceTypesRequest.builder()
                    .minimumCpuCoreCount(4)
                    .minimumMemorySize(8F)
                    .maxResults(100L)
                    .nextToken(nextToken)
                    .build();
            response = client.describeInstanceTypes(describeInstanceTypesRequest);
            resp = response.get();
            nextToken = resp.getBody().getNextToken();
            results.addAll(resp.getBody().getInstanceTypes().getInstanceType());
        } while (StringUtils.isNotEmpty(nextToken));
            
        System.out.println(new Gson().toJson(results));
        // Asynchronous processing of return values
        /*response.thenAccept(resp -> {
            System.out.println(new Gson().toJson(resp));
        }).exceptionally(throwable -> { // Handling exceptions
            System.out.println(throwable.getMessage());
            return null;
        });*/

        // Finally, close the client
        client.close();
    }

}