CrudRepository
interface provides ‘count’ method, it returns number of entities of given type.
Example
List<Employee>
emps = Arrays.asList(emp1, emp2, emp3, emp4);
employeeRepository.saveAll(emps);
long count
= employeeRepository.count();
Find the
below working application.
Step 1: Create model class Employee.
package com.sample.app.model; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name = "employee") public class Employee { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "employee_id") private int id; @Column(name = "first_name") private String firstName; @Column(name = "last_name") private String lastName; 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; } public static EmployeeBuilder builder() { return new EmployeeBuilder(); } public static class EmployeeBuilder { private Employee emp; public EmployeeBuilder() { emp = new Employee(); } public EmployeeBuilder firstName(String firstName) { emp.setFirstName(firstName); return this; } public EmployeeBuilder lastName(String lastName) { emp.setLastName(lastName); return this; } public Employee build() { return emp; } } @Override public String toString() { return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]"; } }
Step 2:
Create
EmployeeRepository interface like below.
package com.sample.app.repository; import org.springframework.data.repository.CrudRepository; import com.sample.app.model.Employee; public interface EmployeeRepository extends CrudRepository<Employee, Integer> { }
Step 3:
Create
‘application.properties’ file under src/main/resources.
logging.level.root=WARN logging.level.org.hibernate=ERROR ## 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 ## JPA specific properties # Creates the schema, destroying previous data. spring.jpa.hibernate.ddl-auto=create spring.jpa.database-platform=org.hibernate.dialect.H2Dialect spring.jpa.show-sql=true spring.jpa.properties.hibernate.format_sql=true ## 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
Step 4:
Define App.java class
like below.
package com.sample.app; import java.util.Arrays; import java.util.List; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.Bean; import com.sample.app.model.Employee; import com.sample.app.repository.EmployeeRepository; @SpringBootApplication public class App { public static void main(String args[]) { SpringApplication.run(App.class, args); } @Bean public CommandLineRunner demo(EmployeeRepository employeeRepository) { return (args) -> { Employee emp1 = Employee.builder().firstName("Ram").lastName("Gurram").build(); Employee emp2 = Employee.builder().firstName("Shiney").lastName("Soo").build(); Employee emp3 = Employee.builder().firstName("Mahesh").lastName("Bhat").build(); Employee emp4 = Employee.builder().firstName("Rahim").lastName("Chelli").build(); List<Employee> emps = Arrays.asList(emp1, emp2, emp3, emp4); employeeRepository.saveAll(emps); long count = employeeRepository.count(); System.out.println("Total employees : " + count); }; } }
Total
project structure looks like below.
Run
App.java, you can see below messages in console.
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.1.6.RELEASE) Hibernate: drop table employee if exists Hibernate: drop sequence if exists hibernate_sequence Hibernate: create sequence hibernate_sequence start with 1 increment by 1 Hibernate: create table employee ( employee_id integer not null, first_name varchar(255), last_name varchar(255), primary key (employee_id) ) Hibernate: call next value for hibernate_sequence Hibernate: call next value for hibernate_sequence Hibernate: call next value for hibernate_sequence Hibernate: call next value for hibernate_sequence Hibernate: insert into employee (first_name, last_name, employee_id) values (?, ?, ?) Hibernate: insert into employee (first_name, last_name, employee_id) values (?, ?, ?) Hibernate: insert into employee (first_name, last_name, employee_id) values (?, ?, ?) Hibernate: insert into employee (first_name, last_name, employee_id) values (?, ?, ?) Hibernate: select count(*) as col_0_0_ from employee employee0_ Total employees : 4
You can
download the complete working application from this link.
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