NamedParameterJdbcTemplate and Collections.singletonMap

In this post I will show you how to use NamedParameterJdbcTemplate and Collections.singletonMap to execute query for returning result. The NamedParameterJdbcTemplate class adds support for programming JDBC statements using named parameters, as opposed to programming JDBC statements using only classic placeholder (?) arguments. The NamedParameterJdbcTemplate class wraps a JdbcTemplate, and delegates to the wrapped JdbcTemplate to do much of its work.

An SqlParameterSource is a source of named parameter values to a NamedParameterJdbcTemplate. The Collections.singletonMap returns an immutable map, mapping only the specified key to the specified value. The returned map is serializable.

Prerequisites

Java 8/19, Gradle 6.5.1, Maven 3.6.3/3.8.5, Spring Boot 2.3.2/3.1.0, MySQL 8.0.17/8.0.31

Project Setup

You can create either gradle or maven based project in your favorite IDE or tool. The name of the project is spring-namedparameterjdbctemplate-collections-singletonmap.

If you are creating gradle based project then you can use below build.gradle script:

buildscript {
	ext {
		springBootVersion = '2.3.2.RELEASE'
	}
	
    repositories {
    	mavenCentral()
    }
    
    dependencies {
    	classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

plugins {
    id 'java-library'
    id 'org.springframework.boot' version "${springBootVersion}"
}

sourceCompatibility = 12
targetCompatibility = 12

repositories {
    mavenCentral()
}

dependencies {
	implementation "org.springframework.boot:spring-boot-starter:${springBootVersion}"
    implementation("org.springframework.boot:spring-boot-starter-jdbc:${springBootVersion}")
    runtime("mysql:mysql-connector-java:8.0.17")
	
	//required for jdk 9 or above
	runtimeOnly('javax.xml.bind:jaxb-api:2.4.0-b180830.0359')
}

If you are creating maven based project then you can use below pom.xml file:

<?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>com.roytuts</groupId>
	<artifactId>spring-namedparameterjdbctemplate-collections-singletonmap</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>19</maven.compiler.source>
		<maven.compiler.target>19</maven.compiler.target>
	</properties>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.1.0</version>
	</parent>
	<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>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.31</version>
		</dependency>
		<!--required only if jdk 9 or higher version is used -->
		<dependency>
			<groupId>javax.xml.bind</groupId>
			<artifactId>jaxb-api</artifactId>
			<version>2.4.0-b180830.0359</version>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>

MySQL Table

You need to create a table called user under roytuts database in MySQL server.

CREATE TABLE IF NOT EXISTS `user` (
  `id` int unsigned NOT NULL,
  `first_name` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL,
  `last_name` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL,
  PRIMARY KEY (`last_name`,`first_name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

Database Configuration

I will use annotation based configuration and you need to create appropriate beans for working with database.

I am using application.properties file which is kept under src/main/resources classpath folder.

The content of the properties file is given below:

spring.datasource.url=jdbc:mysql://localhost/roytuts
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver

#disable schema generation from Hibernate
spring.jpa.hibernate.ddl-auto=none

The required configuration Java class is given below:

@Configuration
@PropertySource("classpath:application.properties")
public class Config {

	@Autowired
	private Environment environment;

	@Bean
	public DataSource dataSource() {

		DriverManagerDataSource ds = new DriverManagerDataSource();
		ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driverClassName"));
		ds.setUrl(environment.getRequiredProperty("spring.datasource.url"));
		ds.setUsername(environment.getRequiredProperty("spring.datasource.username"));
		ds.setPassword(environment.getRequiredProperty("spring.datasource.password"));
		return ds;
	}

	@Bean
	public NamedParameterJdbcTemplate namedParameterJdbcTemplate(DataSource dataSource) {
		NamedParameterJdbcTemplate jdbcTemplate = new NamedParameterJdbcTemplate(dataSource);

		return jdbcTemplate;

	}

}

DAO Class

DAO class is where perform database operations. For my example, here I am going to count the number of users for the given user’s name and return returning the result.

@Component
public class UserDao {

	@Autowired
	private NamedParameterJdbcTemplate jdbcTemplate;

	public int countByName(String name) {
		final String sql = "select count(*) from user where first_name = :name";

		Map<String, String> namedParameters = Collections.singletonMap("name", name);

		return jdbcTemplate.queryForObject(sql, namedParameters, Integer.class);
	}

}

Main Class

A class having main method with @SpringBootApplication annotation is enough to deploy the Spring Boot application into embedded Tomcat server.

@SpringBootApplication
public class SpringNamedParameterJdbcTemplateSingletonMapApp implements CommandLineRunner {

	@Autowired
	private UserDao dao;

	public static void main(String[] args) {
		SpringApplication.run(SpringNamedParameterJdbcTemplateSingletonMapApp.class, args);
	}

	@Override
	public void run(String... args) throws Exception {
		System.out.println("Count: " + dao.countByName("Soumitra"));
	}

}

Testing the Application

Executing the above class will give you the following output:

Count: 1

Source Code

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