歡迎使用阿里雲開發人員工具套件(Alibaba Cloud SDK for Java),DataLake SDK for Java讓您不用複雜編程即可訪問資料湖構建。本教程介紹如何安裝並開始使用DataLake SDK for Java。
前提條件
已安裝Java環境。
DataLake SDK for Java要求使用JDK 1.7或更高版本。
安裝Alibaba Cloud SDK for Java
您可以在Maven Repository中擷取資料湖構建最新的SDK包,擷取地址Maven SDK地址。
<dependency>
<groupId>com.aliyun</groupId>
<artifactId>datalake20200710</artifactId>
<version>2.0.12</version>
</dependency>
請求步驟
初始化請求用戶端。調用介面前,需配置環境變數,通過環境變數讀取存取憑證。
Config authConfig = new Config(); // 阿里雲帳號AccessKey擁有所有API的存取權限,風險很高。強烈建議您建立並使用RAM使用者進行API訪問或日常營運,請登入RAM控制台建立RAM使用者。 // 強烈建議不要將AccessKey ID和AccessKey Secret儲存到代碼裡,會存在密鑰泄漏風險。 // 此處以將AccessKey ID和 AccessKey Secret儲存在環境變數為例說明。運行樣本前,請先配置環境變數。 authConfig.accessKeyId= System.getenv("AK_ENV"); authConfig.accessKeySecret= System.getenv("SK_ENV"); authConfig.type= "access_key"; authConfig.endpoint= "dlf.cn-shanghai.aliyuncs.com"; authConfig.regionId= "cn-shanghai"; Client authClient = new Client(authConfig);
建立請求對象,構造參數。
下述代碼以CreateDatabase(新增中繼資料庫)為例。
CreateDatabaseRequest request = new CreateDatabaseRequest(); request.catalogId = ""; DatabaseInput input = new DatabaseInput(); input.description = ""; input.locationUri = "oss://test"; input.name = "example"; request.databaseInput = input;
執行調用,擷取返回結果。
CreateDatabaseResponseBody response = authClient.createDatabase(request).body;
參考樣本
以下範例程式碼以建立一個中繼資料庫為例。
package com.aliyun.datalake.examples;
import com.aliyun.datalake20200710.Client;
import com.aliyun.datalake20200710.models.CreateDatabaseRequest;
import com.aliyun.datalake20200710.models.CreateDatabaseResponseBody;
import com.aliyun.datalake20200710.models.DatabaseInput;
import com.aliyun.teaopenapi.models.Config;
import com.google.gson.Gson;
public class SchemaExample {
public static void main(String[] args) throws Exception {
// 1 Create and initialize a Config instance.
Config authConfig = new Config();
// 阿里雲帳號AccessKey擁有所有API的存取權限,風險很高。強烈建議您建立並使用RAM使用者進行API訪問或日常營運,請登入RAM控制台建立RAM使用者。
// 強烈建議不要將AccessKey ID和 AccessKey Secret儲存到代碼裡,會存在密鑰泄漏風險。
// 此處以將AccessKey ID和 AccessKey Secret儲存在環境變數為例說明。您也可以根據業務需要,儲存到設定檔裡。
authConfig.accessKeyId= System.getenv("AK_ENV");
authConfig.accessKeySecret= System.getenv("SK_ENV");
authConfig.type = "access_key";
authConfig.endpoint = "dlf.cn-shanghai.aliyuncs.com";
authConfig.regionId = "cn-shanghai";
Client authClient = new Client(authConfig);
// 2 Create an API request and set parameters.
CreateDatabaseRequest request = new CreateDatabaseRequest();
request.catalogId = "";
DatabaseInput input = new DatabaseInput();
input.description = "";
input.locationUri = "oss://test";
input.name = "example";
request.databaseInput = input;
// 3 Initiate the request and handle the response or exceptions.
CreateDatabaseResponseBody response = authClient.createDatabase(request).body;
System.out.println(new Gson().toJson(response));
}
}
調用成功時,返回結果response樣本:
{"code":"OK","message":"","requestId":"1739F0B0-A94E-49AC-95FC-C1CE5E4171FA","success":true}
調用出現異常時,SDK會將狀態代碼和錯誤資訊封裝成異常拋出給調用方,樣本:
Exception in thread "main" com.aliyun.tea.TeaException: code: 409, Database example already exists request id: 598B1E2F-9AEF-4B13-AE4D-EB8733B643EB
at com.aliyun.teaopenapi.Client.doROARequest(Client.java:303)
at com.aliyun.datalake20200710.Client.createDatabaseWithOptions(Client.java:790)
at com.aliyun.datalake20200710.Client.createDatabase(Client.java:772)
at com.aliyun.datalake.examples.SchemaExample.main(SchemaExample.java:34)
調用出現網路等未知異常時,SDK會直接拋出,樣本:
Exception in thread "main" com.aliyun.tea.TeaException
at com.aliyun.tea.Tea.doAction(Tea.java:67)
at com.aliyun.teaopenapi.Client.doROARequest(Client.java:292)
at com.aliyun.datalake20200710.Client.createDatabaseWithOptions(Client.java:790)
at com.aliyun.datalake20200710.Client.createDatabase(Client.java:772)
at com.aliyun.datalake.examples.SchemaExample.main(SchemaExample.java:34)
Caused by: java.net.UnknownHostException: dlf.cn-shanghai.aliyuncs.com
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
at java.net.InetAddress.getAllByName(InetAddress.java:1192)
at java.net.InetAddress.getAllByName(InetAddress.java:1126)
at okhttp3.Dns$1.lookup(Dns.java:39)
at okhttp3.internal.connection.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:171)
at okhttp3.internal.connection.RouteSelector.nextProxy(RouteSelector.java:137)
at okhttp3.internal.connection.RouteSelector.next(RouteSelector.java:82)
at okhttp3.internal.connection.StreamAllocation.findConnection(StreamAllocation.java:171)
at okhttp3.internal.connection.StreamAllocation.findHealthyConnection(StreamAllocation.java:121)
at okhttp3.internal.connection.StreamAllocation.newStream(StreamAllocation.java:100)
at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:42)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:93)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:120)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:185)
at okhttp3.RealCall.execute(RealCall.java:69)
at com.aliyun.tea.Tea.doAction(Tea.java:64)
... 4 more
最佳實務
為了便於返回結果的統一處理,擷取到和API文檔一致的異常結果,我們可以通過一些固定的寫法,來處理SDK正常或異常的返回結果。
例如,我們把API調用層用統一的方法來封裝:
public class AbstractAPI {
protected final Client client;
public AbstractAPI(Client client) {
this.client = client;
}
public <M, V extends ResultModel<M>> ResultModel<M> call(Callable<V> c) throws Exception {
try {
return c.call();
} catch (TeaException e) {
Map<String, Object> data = e.getData();
if (data!= null && data.get("Code") != null) {
return TeaModel.toModel(data, new ResultModel<M>());
} else {
throw e;
}
}
}
}
對於具體的API,可以繼承上面的類,用適合自己的參數構造調用方法。
public class DatabaseAPI extends AbstractAPI {
public DatabaseAPI(Client client) {
super(client);
}
public ResultModel<Void> createDatabase(String catalogId, String databaseName, String description,
String locationUri, Map<String, String> parameters,
String ownerName, String ownerType, PrincipalPrivilegeSet privileges) throws Exception {
return call(()-> {
CreateDatabaseRequest request = new CreateDatabaseRequest();
request.catalogId = catalogId;
DatabaseInput input = new DatabaseInput();
input.description = description;
input.locationUri = locationUri;
input.parameters = parameters;
input.name = databaseName;
input.ownerName = ownerName;
input.ownerType = ownerType;
input.privileges = privileges;
request.databaseInput = input;
CreateDatabaseResponseBody response = client.createDatabase(request).body;
return new ResultModel<>(response.success, response.code, response.message,
response.requestId);
});
}
}
這樣,在使用每個API的時候,就可以直接拿到標準的Response了:
public class SchemaExample {
public static void main(String[] args) throws Exception {
// 1 Create and initialize a Config instance.
Config authConfig = new Config();
// 阿里雲帳號AccessKey擁有所有API的存取權限,風險很高。強烈建議您建立並使用RAM使用者進行API訪問或日常營運,請登入RAM控制台建立RAM使用者。
// 強烈建議不要將AccessKey ID和AccessKey Secret儲存到代碼裡,會存在密鑰泄漏風險
// 此處以將AccessKey ID和 AccessKey Secret儲存在環境變數為例說明。運行程式碼範例前,請先配置環境變數。
authConfig.accessKeyId= System.getenv("AK_ENV");
authConfig.accessKeySecret= System.getenv("SK_ENV");
authConfig.type = "access_key";
authConfig.endpoint = "dlf.cn-shanghai.aliyuncs.com";
authConfig.regionId = "cn-shanghai";
Client authClient = new Client(authConfig);
// 2 Initiate the request and handle the response or exceptions.
ResultModel<Void> response = new DatabaseAPI(authClient).createDatabase("", "example3", "",
"oss://test", null,
null, null, null);
System.out.println(new Gson().toJson(response));
}
}
建立成功時的response樣本:
{"success":true,"code":"OK","message":"","requestId":"50778D55-696D-45FA-8328-B01983F6CEB1"}
建立出錯時的response樣本:
{"success":false,"code":"AlreadyExists","message":"Database example3 already exists","requestId":"94617169-DA17-4020-9027-7D8F89160682","httpStatusCode":409}
更多資訊
DLF目前支援的地區(Region)和網域名稱(Endpoint),請參考已開通的地區和訪問網域名稱。
線上調試和產生SDK樣本。OpenAPI Explorer提供線上調用雲產品API、動態產生SDK範例程式碼和快速檢索介面等功能,能顯著降低使用API的難度,推薦您使用。