How to connect to Google Cloud Storage Data from Spring Boot



Connect to Google Cloud Storage in a Spring Boot Application using CData JDBC Google Cloud Storage Driver

Spring Boot is a framework that makes engineering Java web applications easier. It offers the ability to create standalone applications with minimal configuration. When paired with the CData JDBC driver for Google Cloud Storage, Spring Boot can work with live Google Cloud Storage data. This article shows how to configure data sources and retrieve data in your Java Spring Boot Application, using the CData JDBC Driver for Google Cloud Storage.

With built-in optimized data processing, the CData JDBC Driver offers unmatched performance for interacting with live Google Cloud Storage data. When you issue complex SQL queries to Google Cloud Storage, the driver pushes supported SQL operations, like filters and aggregations, directly to Google Cloud Storage and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations). Its built-in dynamic metadata querying allows you to work with and analyze Google Cloud Storage data using native data types.

Creating the Spring Boot Project in Java

In an IDE (in this tutorial, we use IntelliJ), choose a Maven project: In the generated project, go to the pom.xml file, and add the required dependencies for Spring Boot:

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.7.2</version> <relativePath/> </parent> <groupId>com.example</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-install-plugin</artifactId> <version>2.5.1</version> <executions> <execution> <id>id.install-file</id> <phase>clean</phase> <goals> <goal>install-file</goal> </goals> <configuration> <file>C:\Program Files\CData[product_name] ####\lib\cdata.jdbc.googlecloudstorage.jar</file> <groupId>org.cdata.connectors</groupId> <artifactId>cdata-googlecloudstorage-connector</artifactId> <version>23</version> <packaging>jar</packaging> </configuration> </execution> </executions> </plugin> </plugins> </build> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> <version>2.7.0</version> </dependency> <dependency> <groupId>org.cdata.connectors</groupId> <artifactId>cdata-googlecloudstorage-connector</artifactId> <version>23</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <distributionManagement> <repository> <uniqueVersion>false</uniqueVersion> <id>test</id> <name>My Repository</name> <url>scp://repo/maven2</url> <layout>default</layout> </repository> </distributionManagement> </project>

Note: The year (####) and the version number (as seen in the provided XML script) should be adjusted according to the current version of the CData JDBC driver being utilized.

Project Structure

In the java directory, create a new package. Usually the name of the package is the name of the groupId (com.example) followed by the artifactId (.MDS).

Mark the "java" directory as the "Sources Root" (denoted by a blue color). To do this, right-click the java directory and choose Mark Directory as -> Sources Root (As shown below). Additionally, mark the "resources" directory as the "Resources Root."

Store Database Connection Properties

Create an "application.properties" file to store the database connection properties. To do this, right-click on the "resources" folder, opt for New -> File, input the file name as "application.properties," and press Enter.

In the application.properties file, we set the configuration properties for the Google Cloud Storage JDBC Driver, using the Class name and JDBC URL:

spring.datasource.driver=cdata.jdbc.googlecloudstorage.GoogleCloudStorageDriver spring.datasource.url=jdbc:googlecloudstorage:ProjectId='project1';InitiateOAuth=GETANDREFRESH

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the Google Cloud Storage JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.googlecloudstorage.jar

Authenticate with a User Account

You can connect without setting any connection properties for your user credentials. After setting InitiateOAuth to GETANDREFRESH, you are ready to connect.

When you connect, the Google Cloud Storage OAuth endpoint opens in your default browser. Log in and grant permissions, then the OAuth process completes

Authenticate with a Service Account

Service accounts have silent authentication, without user authentication in the browser. You can also use a service account to delegate enterprise-wide access scopes.

You need to create an OAuth application in this flow. See the Help documentation for more information. After setting the following connection properties, you are ready to connect:

  • InitiateOAuth: Set this to GETANDREFRESH.
  • OAuthJWTCertType: Set this to "PFXFILE".
  • OAuthJWTCert: Set this to the path to the .p12 file you generated.
  • OAuthJWTCertPassword: Set this to the password of the .p12 file.
  • OAuthJWTCertSubject: Set this to "*" to pick the first certificate in the certificate store.
  • OAuthJWTIssuer: In the service accounts section, click Manage Service Accounts and set this field to the email address displayed in the service account Id field.
  • OAuthJWTSubject: Set this to your enterprise Id if your subject type is set to "enterprise" or your app user Id if your subject type is set to "user".
  • ProjectId: Set this to the Id of the project you want to connect to.

The OAuth flow for a service account then completes.

After setting the properties in the application.properties file, we now configure them.

Data Source Configuration

First, we mark the Google Cloud Storage data source as our primary data source. Then, we create a Data Source Bean.

Create a DriverManagerDataSource.java file and create a Bean within it, as shown below. If @Bean gives an error, Spring Boot may not have loaded properly. To fix this, go to File -> Invalidate Caches and restart. Additionally, make sure that Maven has added the Spring Boot dependencies.

To create a data source bean, we use the DriverManagerDataSource Class. This class allows us to set the properties of the data source. To create this Java class, right-click on "com.example.MDS" package, and choose New -> Java Class.

The following code shows the bean definition of our data source. Each driver should have a bean.

import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.jdbc.DataSourceBuilder; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Primary; import org.springframework.core.env.Environment; import javax.sql.DataSource; public class DriverManagerDataSource{ @Autowired private static Environment env; @Bean(name ="GoogleCloudStorage") @Primary public static DataSource GoogleCloudStorageDataSource() { DataSourceBuilder<?> dataSourceBuilder = DataSourceBuilder.create(); dataSourceBuilder.driverClassName("cdata.jdbc.googlecloudstorage.GoogleCloudStorageDriver"); dataSourceBuilder.url("jdbc:googlecloudstorage:ProjectId='project1';InitiateOAuth=GETANDREFRESH"); return dataSourceBuilder.build(); } //@Override public void setEnvironment( final Environment environment) { env=environment; } }

Next, move the Google Cloud Storage jar file to the Documents folder (see path in command below) - The idea is to have a path without any spaces for the jar file. Then, click the Maven icon (top right corner of IntelliJ) and click "Execute Maven Goal." Now, run the following command:

mvn install:install-file "-Dfile=C:\Program Files\CData[product_name] ####\lib\cdata.jdbc.googlecloudstorage.jar" -DgroupId=org.cdata.connectors -DartifactId=cdata-googlecloudstorage-connector -Dversion=23 -Dpackaging=jar

Follow either of the given steps to run this command:

  1. The "-Dfile location" can be kept as the default installation path of the CData JDBC Driver. Make sure to keep the path in quotations in this case. Also, change the year and "Dversion" based on the current version of the driver being used.
  2. As mentioned earlier in the article, in case you relocate the jar file to the Documents folder, make sure to modify the path in the provided command. In such instances, avoid enclosing the Dfile location in quotations and edit "Dversion" based on the current version of the driver being used.

After pressing enter, we see the following output:

Testing the Connection

The last step is testing the connection. Create a new Java class following the format (e.g., "MDSApplication"). You have the flexibility to select any name for the application class. We call the data source in the main method of MDSApplication.java:

import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration; import java.sql.Connection; import java.sql.SQLException; import static com.example.demo.DriverManagerDataSources.GoogleCloudStorageDataSource; @SpringBootApplication(exclude = {DataSourceAutoConfiguration.class}) public class MDSApplication { //remove the comment on the line below public static void main (){ SpringApplication.run(DemoApplication.class, args); Connection conn = GoogleCloudStorageDataSource().getConnection(); System.out.println("Catalog: "+ conn.getCatalog()); } }

The output generated should look like this:

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