Build a Java application

Client driver: Yugabyte JDBC

YugabyteDB YSQL is fully compatible with the PostgreSQL JDBC driver, allowing Java programmers to connect to YugabyteDB database to execute DMLs and DDLs using the JDBC APIs. The YugabyteDB JDBC smart driver is built on the PostgreSQL JDBC driver, with additional connection load balancing features.

The following tutorial shows a small Java application that connects to a YugabyteDB cluster using the topology-aware YugabyteDB JDBC driver and performs basic SQL operations. Use the application as a template to get started with YugabyteDB Aeon in Java.

Prerequisites

Clone the application from GitHub

Clone the sample application to your computer:

git clone https://github.com/YugabyteDB-Samples/yugabyte-simple-java-app.git && cd yugabyte-simple-java-app

Provide connection parameters

If your cluster is running on YugabyteDB Aeon, you need to modify the connection parameters so that the application can establish a connection to the YugabyteDB cluster. (You can skip this step if your cluster is running locally and listening on 127.0.0.1:5433.)

To do this:

  1. Open the app.properties file located in the application src/main/resources/ folder.

  2. Set the following configuration parameters:

    • host - the host name of your YugabyteDB cluster. For local clusters, use the default (127.0.0.1). For YugabyteDB Aeon, select your cluster on the Clusters page, and click Settings. The host is displayed under Connection Parameters.
    • port - the port number for the driver to use (the default YugabyteDB YSQL port is 5433).
    • database - the name of the database you are connecting to (the default is yugabyte).
    • dbUser and dbPassword - the username and password for the YugabyteDB database. For local clusters, use the defaults (yugabyte and yugabyte). For YugabyteDB Aeon, use the credentials in the credentials file you downloaded.
    • sslMode - the SSL mode to use. YugabyteDB Aeon requires SSL connections; use verify-full.
    • sslRootCert - the full path to the YugabyteDB Aeon cluster CA certificate.

  3. 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 Sandbox 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 YugabyteDB Aeon.

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 YugabyteDB 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

Connect an application using the PostgreSQL JDBC driver