Spring boot jdbc: KeyHolder example: Get generated key

KeyHolder interface is used to retrieve automatically generated key of a record while creating the new record.

Step 1: Instantiate KeyHolder.

KeyHolder keyHolder = new GeneratedKeyHolder();

Step 2: Instantiate PreparedStatementCreator.

PreparedStatementCreator preparedStmtCreator = new PreparedStatementCreator() {

         @Override

         public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {

                  PreparedStatement ps = connection.prepareStatement(

                                    "INSERT INTO employees (first_name, last_name) VALUES (?, ?)", new String[] { "id" });

                  ps.setString(1, emp.getFirstName());

                  ps.setString(2, emp.getLastName());

                  return ps;

         }

};

Step 3: Execute updated method by passing preparedStmtCreator and keyHolder as arguments.

jdbcTemplate.update(preparedStmtCreator, keyHolder);

Step 4: Get the key from KeyHolder.

int id = (Integer) keyHolder.getKey();

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 serial, first_name VARCHAR(255), last_name VARCHAR(255), PRIMARY KEY(id)) ");

   Employee emp1 = new Employee("Ram", "Gurram");
   Employee emp2 = new Employee("Moutwika", "Maj");
   Employee emp3 = new Employee("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(String firstName, String lastName) {
  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.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.PreparedStatementCreator;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.GeneratedKeyHolder;
import org.springframework.jdbc.support.KeyHolder;
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) {
  KeyHolder keyHolder = new GeneratedKeyHolder();

  PreparedStatementCreator preparedStmtCreator = new PreparedStatementCreator() {

   @Override
   public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {
    PreparedStatement ps = connection.prepareStatement(
      "INSERT INTO employees (first_name, last_name) VALUES (?, ?)", new String[] { "id" });
    ps.setString(1, emp.getFirstName());
    ps.setString(2, emp.getLastName());
    return ps;
   }

  };

  jdbcTemplate.update(preparedStmtCreator, keyHolder);

  int id = (Integer) keyHolder.getKey();

  Employee emp1 = new Employee();
  jdbcTemplate.query("SELECT * FROM employees WHERE id = " + id, 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