Spring boot jdbc: Read records from table

Step 1: Create a RowMapper that maps ResultSet to an Employee.

private static final RowMapper<Employee> EMPLOYEE_ROW_MAPPER = (rs, rowNum) -> {

    Employee emp1 = new Employee();

    emp1.setId(rs.getInt("id"));

    emp1.setFirstName(rs.getString("first_name"));

    emp1.setLastName(rs.getString("last_name"));

    return emp1;

};

Step 2: Use query method of jdbcTemplate to get all the employees.

List<Employee> emps = jdbcTemplate.query("SELECT * FROM employees", EMPLOYEE_ROW_MAPPER);

Find the below working application.

App.java

package com.sample.app;

import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.jdbc.core.JdbcTemplate;

import com.sample.app.entity.Employee;
import com.sample.app.repository.EmployeeRepository;

@SpringBootApplication
public class App {
    private static final Logger log = LoggerFactory.getLogger(App.class);

    @Autowired
    JdbcTemplate jdbcTemplate;

    @Autowired
    EmployeeRepository employeeRepository;

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

    @Bean
    public CommandLineRunner demo() {
        return (args) -> {
            log.info("Creating tables");

            jdbcTemplate.execute("DROP TABLE employees IF EXISTS");
            jdbcTemplate.execute(
                    "CREATE TABLE employees (id int, first_name VARCHAR(255), last_name VARCHAR(255), PRIMARY KEY(id)) ");

            Employee emp1 = new Employee(1, "Ram", "Gurram");
            Employee emp2 = new Employee(2, "Moutwika", "Maj");
            Employee emp3 = new Employee(3, "Anusha", "R");

            employeeRepository.save(emp1);
            employeeRepository.save(emp2);
            employeeRepository.save(emp3);

            System.out.println("\nPrinting All Employees\n");

            List<Employee> emps = employeeRepository.all();
            emps.forEach(customer -> System.out.println(customer));

        };
    }

}

Employee.java

package com.sample.app.entity;

public class Employee {
    private int id;
    private String firstName;
    private String lastName;

    public Employee(int id, String firstName, String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }
    
    public Employee() {}

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("Employee [id=").append(id).append(", firstName=").append(firstName).append(", lastName=")
                .append(lastName).append("]");
        return builder.toString();
    }

}

EmployeeRepository.java

package com.sample.app.repository;

import java.util.List;

import com.sample.app.entity.Employee;

public interface EmployeeRepository {

    public Employee save(Employee emp);
    
    public List<Employee> all();
}

EmployeeRepositoryImpl.java

package com.sample.app.repository.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;

import com.sample.app.entity.Employee;
import com.sample.app.repository.EmployeeRepository;

@Repository
public class EmployeeRepositoryImpl implements EmployeeRepository {

    @Autowired
    JdbcTemplate jdbcTemplate;

    private static final RowMapper<Employee> EMPLOYEE_ROW_MAPPER = (rs, rowNum) -> {
        Employee emp1 = new Employee();
        emp1.setId(rs.getInt("id"));
        emp1.setFirstName(rs.getString("first_name"));
        emp1.setLastName(rs.getString("last_name"));

        return emp1;
    };

    @Override
    public Employee save(Employee emp) {
        jdbcTemplate.update("INSERT INTO employees (id, first_name, last_name) VALUES (?, ?, ?)", emp.getId(),
                emp.getFirstName(), emp.getLastName());

        Employee emp1 = new Employee();
        jdbcTemplate.query("SELECT * FROM employees WHERE id = " + emp.getId(), rs -> {
            emp1.setId(rs.getInt("id"));
            emp1.setFirstName(rs.getString("first_name"));
            emp1.setLastName(rs.getString("last_name"));
        });
        return emp1;
    }

    @Override
    public List<Employee> all() {
        return jdbcTemplate.query("SELECT * FROM employees", EMPLOYEE_ROW_MAPPER);
    }

}

application.properties

logging.level.root=WARN

## H2 specific properties
spring.h2.console.enabled=true
spring.h2.console.path=/h2

spring.datasource.url=jdbc:h2:file:~/db/myOrg.db;DB_CLOSE_ON_EXIT=FALSE;DB_CLOSE_DELAY=-1;

spring.datasource.username=krishna
spring.datasource.password=password123

spring.datasource.driverClassName=org.h2.Driver

## Database connection pooling properties
# Number of ms to wait before throwing an exception if no connection is available.
spring.datasource.max-wait=10000

# Maximum number of active connections that can be allocated from this pool at the same time.
spring.datasource.tomcat.max-active=10
spring.datasource.tomcat.max-idle=5
spring.datasource.tomcat.min-idle=3

pom.xml

<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>springJDBC</groupId>
    <artifactId>springJDBC</artifactId>
    <version>1</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>
    </dependencies>

</project>

Total project structure looks like below.

Run App.java, you can see below messages in console.

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.6.RELEASE)


Printing All Employees

Employee [id=1, firstName=Ram, lastName=Gurram]
Employee [id=2, firstName=Moutwika, lastName=Maj]
Employee [id=3, firstName=Anusha, lastName=R]

You can download complete working application from this link.

    

Previous                                                    Next                                                    Home