Spring Data

Overview

I am running MySQL Ver 14.14 Distrib 5.6.47 in my local with sakila database loaded. Related documentation can be found here.

JdbcTemplate Hello World

The API docs for JdbcTemplate can be found here.

pom.xml

<?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 
                             http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>biz.tugay</groupId>
    <artifactId>my-spring-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.0.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

application.properties

spring.jpa.hibernate.ddl-auto=none
spring.datasource.url=jdbc:mysql://localhost:3306/sakila?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=

ActorDao.java

@Component
public class ActorDao {

    static class Actor {
        String first_name;
        String last_name;
    }

    static class ActorRowMapper implements RowMapper<Actor> {
        @Override
        public Actor mapRow(ResultSet resultSet, int rowNumber) throws SQLException {
            Actor actor = new Actor();
            actor.first_name = resultSet.getString("first_name");
            actor.last_name = resultSet.getString("last_name");
            return actor;
        }
    }

    private final JdbcTemplate jdbcTemplate;

    private final ActorRowMapper actorRowMapper = new ActorRowMapper();

    public ActorDao(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    public void printActors() {
        List<Actor> actors = 
          jdbcTemplate.query("SELECT * FROM Actor LIMIT 10", actorRowMapper);
        actors.forEach(actor -> 
          System.out.println(
            String.format("%s %s", actor.first_name, actor.last_name)));
    }
}

DemoApplication.java

@SpringBootApplication
public class DemoApplication {
    public static void main(String[] args) {
        ConfigurableApplicationContext ctx = 
            SpringApplication.run(DemoApplication.class, args);

        ActorDao actorDao = ctx.getBean(ActorDao.class);
        actorDao.printActors();
    }
}

NamedParameterJdbcTemplate

A simple example with NamedParameterJdbcTemplate:

public List<Integer> filmsActorPlayedIn(int actorId) {
    String query = "SELECT film_id FROM film_actor WHERE actor_id = :actor_id";
    return namedJdbcTemplate.queryForList(
        query, Collections.singletonMap("actor_id", actorId), Integer.class);
}

To refresh your memory on differences between JdbcTemplate and this class, take a look at this answer.

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