Build a Java application
The following tutorial shows a small Java application that connects to a YugabyteDB cluster using the topology-aware Yugabyte JDBC driver and performs basic SQL operations. Use the application as a template to get started with Yugabyte Cloud in Java.
Prerequisites
This tutorial requires the following.
Yugabyte Cloud
- You have a cluster deployed in Yugabyte Cloud. To get started, use the Quick start.
- You downloaded the cluster CA certificate. Refer to Download your cluster certificate.
- You have added your computer to the cluster IP allow list. Refer to Assign IP Allow Lists.
Other packages
- Java Development Kit (JDK) 1.8, or later, is installed. JDK installers for Linux and macOS can be downloaded from Oracle, Adoptium (OpenJDK), or Azul Systems (OpenJDK). Homebrew users on macOS can install using
brew install openjdk. - Apache Maven 3.3 or later, is installed.
Clone the application from GitHub
Clone the sample application to your computer:
git clone https://github.com/yugabyte/yugabyte-simple-java-app.git && cd yugabyte-simple-java-app
Provide connection parameters
The application needs to establish a connection to the YugabyteDB cluster. To do this:
-
Open the
app.propertiesfile located in the applicationsrc/main/resources/folder. -
Set the following configuration parameters:
- host - the host name of your YugabyteDB cluster. To obtain a Yugabyte Cloud cluster host name, sign in to Yugabyte Cloud, select your cluster on the Clusters page, and click Settings. The host is displayed under Network Access.
- port - the port number that will be used by the JDBC driver (the default YugabyteDB YSQL port is 5433).
- dbUser and dbPassword - the username and password for the YugabyteDB database. If you are using the credentials you created when deploying a cluster in Yugabyte Cloud, these can be found in the credentials file you downloaded.
- sslMode - the SSL mode to use. Yugabyte Cloud requires SSL connections; use
verify-full. - sslRootCert - the full path to the Yugabyte Cloud cluster CA certificate.
-
Save the file.
Build and run the application
First build the application.
$ mvn clean package
Start the application.
$ java -cp target/yugabyte-simple-java-app-1.0-SNAPSHOT.jar SampleApp
If you are running the application on a free or single node cluster, the driver displays a warning that the load balance failed and will fall back to a regular connection.
You should see output similar to the following:
>>>> Successfully connected to YugabyteDB!
>>>> Successfully created DemoAccount table.
>>>> Selecting accounts:
name = Jessica, age = 28, country = USA, balance = 10000
name = John, age = 28, country = Canada, balance = 9000
>>>> Transferred 800 between accounts.
>>>> Selecting accounts:
name = Jessica, age = 28, country = USA, balance = 9200
name = John, age = 28, country = Canada, balance = 9800
You have successfully executed a basic Java application that works with Yugabyte Cloud.
Explore the application logic
Open the SampleApp.java file in the application /src/main/java/ folder to review the methods.
main
The main method establishes a connection with your cluster via the topology-aware Yugabyte JDBC driver.
YBClusterAwareDataSource ds = new YBClusterAwareDataSource();
ds.setUrl("jdbc:yugabytedb://" + settings.getProperty("host") + ":"
+ settings.getProperty("port") + "/yugabyte");
ds.setUser(settings.getProperty("dbUser"));
ds.setPassword(settings.getProperty("dbPassword"));
// Additional SSL-specific settings. See the source code for details.
Connection conn = ds.getConnection();
createDatabase
The createDatabase method uses PostgreSQL-compliant DDL commands to create a sample database.
Statement stmt = conn.createStatement();
stmt.execute("CREATE TABLE IF NOT EXISTS " + TABLE_NAME +
"(" +
"id int PRIMARY KEY," +
"name varchar," +
"age int," +
"country varchar," +
"balance int" +
")");
stmt.execute("INSERT INTO " + TABLE_NAME + " VALUES" +
"(1, 'Jessica', 28, 'USA', 10000)," +
"(2, 'John', 28, 'Canada', 9000)");
selectAccounts
The selectAccounts method queries your distributed data using the SQL SELECT statement.
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM " + TABLE_NAME);
while (rs.next()) {
System.out.println(String.format("name = %s, age = %s, country = %s, balance = %s",
rs.getString(2), rs.getString(3),
rs.getString(4), rs.getString(5)));
}
transferMoneyBetweenAccounts
The transferMoneyBetweenAccounts method updates your data consistently with distributed transactions.
Statement stmt = conn.createStatement();
try {
stmt.execute(
"BEGIN TRANSACTION;" +
"UPDATE " + TABLE_NAME + " SET balance = balance - " + amount + "" + " WHERE name = 'Jessica';" +
"UPDATE " + TABLE_NAME + " SET balance = balance + " + amount + "" + " WHERE name = 'John';" +
"COMMIT;"
);
} catch (SQLException e) {
if (e.getSQLState().equals("40001")) {
System.err.println("The operation is aborted due to a concurrent transaction that is" +
" modifying the same set of rows. Consider adding retry logic for production-grade applications.");
e.printStackTrace();
} else {
throw e;
}
}
Learn more
Sample Java application demonstrating load balancing