Spring Boot BeanPropertyRowMapper
last modified July 6, 2020
Spring Boot BeanPropertyRowMapper tutorial shows how to convert a table row into a new instance of a specified bean class with BeanPropertyRowMapper.
Spring Boot is a popular application framework for creating enterprise application in Java, Kotlin, or Groovy.
BeanPropertyRowMapper
BeanPropertyRowMapper
is a RowMapper
implementation that
converts a table row into a new instance of the specified mapped target class. The mapped
target class must be a top-level class and it must have a default or no-arg constructor.
Spring Boot BeanPropertyRowMapper example
The following application uses a BeanPropertyRowMapper
to map a result set
row to a City
bean.
pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ │ Application.java │ │ │ MyRunner.java │ │ ├───model │ │ │ City.java │ │ └───service │ │ CityService.java │ │ ICityService.java │ └───resources │ application.properties │ data-h2.sql │ schema-h2.sql └───test └───java
This is the project structure of the Spring Boot application.
<?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.zetcode</groupId> <artifactId>SpringBootBeanPropertyRowMapper</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <properties> <java.version>11</java.version> </properties> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.2.4.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
This is the Maven build file. The RowMapper
resides in
spring-boot-starter-jdbc
. In the maven-compiler-plugin
configuration, we enable preview features.
spring.main.banner-mode=off spring.datasource.platform=h2 spring.datasource.driverClassName=org.h2.Driver spring.datasource.url=jdbc:h2:mem:testdb;MODE=PostgreSQL
In the application.properties
, we turn off the Spring Boot banner
and set up the H2 datasource.
CREATE TABLE cities(id BIGINT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(255), population BIGINT);
This SQL script creates the cities table.
INSERT INTO cities(name, population) VALUES('Bratislava', 432000); INSERT INTO cities(name, population) VALUES('Budapest', 1759000); INSERT INTO cities(name, population) VALUES('Prague', 1280000); INSERT INTO cities(name, population) VALUES('Warsaw', 1748000); INSERT INTO cities(name, population) VALUES('Los Angeles', 3971000); INSERT INTO cities(name, population) VALUES('New York', 8550000); INSERT INTO cities(name, population) VALUES('Edinburgh', 464000); INSERT INTO cities(name, population) VALUES('Berlin', 3671000);
The SQL script fills the table with data.
package com.zetcode.model; import java.util.Objects; public class City { private Long id; private String name; private int population; public City() { } public City(Long id, String name, int population) { this.id = id; this.name = name; this.population = population; } public Long getId() { return id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getPopulation() { return population; } public void setPopulation(int population) { this.population = population; } @Override public int hashCode() { int hash = 7; hash = 79 * hash + Objects.hashCode(this.id); hash = 79 * hash + Objects.hashCode(this.name); hash = 79 * hash + this.population; return hash; } @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final City other = (City) obj; if (this.population != other.population) { return false; } if (!Objects.equals(this.name, other.name)) { return false; } return Objects.equals(this.id, other.id); } @Override public String toString() { final StringBuilder sb = new StringBuilder("City{"); sb.append("id=").append(id); sb.append(", name='").append(name).append('\''); sb.append(", population=").append(population); sb.append('}'); return sb.toString(); } }
This is the City
model class.
package com.zetcode.service; import com.zetcode.model.City; import java.util.List; public interface ICityService { List<City> findAll(); City findById(Long id); }
There are two contract methods in the ICityService
.
package com.zetcode.service; import com.zetcode.model.City; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.jdbc.core.BeanPropertyRowMapper; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.stereotype.Service; import java.util.List; @Service public class CityService implements ICityService { @Autowired private JdbcTemplate jtm; @Override public List<City> findAll() { String sql = "SELECT * FROM cities"; return jtm.query(sql, BeanPropertyRowMapper.newInstance(City.class)); } @Override public City findById(Long id) { String sql = "SELECT * FROM cities WHERE id = ?"; return jtm.queryForObject(sql, new Object[]{id}, BeanPropertyRowMapper.newInstance(City.class)); } }
We have the implementations of the two contract methods, using the BeanPropertyRowMapper
.
The column values are mapped based on matching the column name as obtained from result set
meta-data to public setters for the corresponding properties.
package com.zetcode; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); } }
The Application
sets up the Spring Boot application.
package com.zetcode; import com.zetcode.service.ICityService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.CommandLineRunner; import org.springframework.stereotype.Component; @Component public class MyRunner implements CommandLineRunner { @Autowired private ICityService cityService; @Override public void run(String... args) throws Exception { var city = cityService.findById(1L); System.out.println(city); var data = cityService.findAll(); System.out.println(data); } }
In the MyRunner
, we find one city by its Id and then find all cities.
In this tutorial, we have worked with Spring Boot BeanPropertyRowMapper.
List Spring Boot tutorials.