Wednesday, 29 June 2022

spring boot: ehcache hello world example

Ehcache is a high-performance caching library for Java. In this post, I am going to explain how to integrate Ehcache with spring boot application.

 

Step 1: Enable caching in your spring boot application.

 

Step 2: Create ehcache.xml configuration and define the caches there.

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://www.ehcache.org/v3"
	xmlns:jsr107="http://www.ehcache.org/v3/jsr107"
	xsi:schemaLocation="
            http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.0.xsd
            http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">

	<cache alias="myEmployeeCache">
		<key-type>java.lang.Object</key-type>
		<value-type>java.lang.Object</value-type>
		<expiry>
			<ttl unit="seconds">10</ttl>
		</expiry>

		<resources>
			<heap unit="entries">2</heap>
			<offheap unit="MB">10</offheap>
		</resources>
	</cache>


</config>

 

Above snippet defines a cache ‘myEmployeeCache’ where key and object are of type Object. An entry can live 10 seconds in the cache.

 

Step 3: Specify cache configuration to spring by adding below property.

spring:
  cache:
    jcache:
      config: classpath:ehcache.xml

Find the below working application.

 

Step 1: Create new maven project ‘spring-ehcache-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>spring-ehcache-demo</artifactId>
	<version>1</version>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.6.6</version>
	</parent>

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

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

		<dependency>
			<groupId>org.ehcache</groupId>
			<artifactId>ehcache</artifactId>
		</dependency>

		<dependency>
			<groupId>javax.cache</groupId>
			<artifactId>cache-api</artifactId>
		</dependency>

	</dependencies>
</project>

 

Step 3: Create application.yml file under src/main/resources folder.

 

application.yml

spring:
  cache:
    jcache:
      config: classpath:ehcache.xml

 

Step 4: Create ehcache.xml file under src/main/resources folder.

 

ehcache.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://www.ehcache.org/v3"
	xmlns:jsr107="http://www.ehcache.org/v3/jsr107"
	xsi:schemaLocation="
            http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.0.xsd
            http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">

	<cache alias="myEmployeeCache">
		<key-type>java.lang.Object</key-type>
		<value-type>java.lang.Object</value-type>
		<expiry>
			<ttl unit="seconds">10</ttl>
		</expiry>

		<resources>
			<heap unit="entries">2</heap>
			<offheap unit="MB">10</offheap>
		</resources>
	</cache>


</config>

Step 5: Define Employee model class.

 

Employee.java

package com.sample.app.model;

import java.io.Serializable;

public class Employee implements Serializable{
	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 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() {
		return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]";
	}

}

Step 6: Define EmployeeService class.

 

EmployeeService.java

package com.sample.app.service;

import java.util.ArrayList;
import java.util.List;

import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import com.sample.app.model.Employee;

@Service
@CacheConfig(cacheNames = "myEmployeeCache")
public class EmployeeService {

	private static List<Employee> emps = new ArrayList<>();

	static {
		emps.add(new Employee(1, "Ram", "Kota"));
		emps.add(new Employee(2, "Raj", "Majety"));
		emps.add(new Employee(3, "PTR", "Navakotla"));
		emps.add(new Employee(4, "Krishna", "Boppana"));
	}

	@Cacheable(key = "{#id}")
	public Employee getEmployeeById(int id) {
		System.out.println("getEmployeeById: Getting the informaiton from internal list");
		
		for (Employee emp : emps) {
			if (id == emp.getId()) {
				return emp;
			}
		}
		return null;
	}

	@Cacheable(key = "{#name}")
	public Employee getEmployeeByFirstName(String name) {
		System.out.println("getEmployeeByFirstName: Getting the informaiton from internal list");
		
		for (Employee emp : emps) {
			if (name.equals(emp.getFirstName())) {
				return emp;
			}
		}
		return null;
	}
}

Step 7: Define CacheConfig class.

 

CacheConfig.java

package com.sample.app.config;

import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableCaching
public class CacheConfig {

}

Step 8: Define main application class.

 

App.java

package com.sample.app;

import java.util.concurrent.TimeUnit;

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 com.sample.app.model.Employee;
import com.sample.app.service.EmployeeService;

@SpringBootApplication
public class App {

	@Autowired
	private EmployeeService empService;

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

	public void getEmployeeDetails() {

		Employee emp = empService.getEmployeeById(1);
		System.out.println(emp);

		emp = empService.getEmployeeByFirstName("Krishna");
		System.out.println(emp);
	}

	@Bean
	public CommandLineRunner demo() {
		return (args) -> {

			getEmployeeDetails();

			System.out.println("\nSleeping for 4 seconds");
			TimeUnit.SECONDS.sleep(4);
			getEmployeeDetails();

			System.out.println("\n\nSleeping for 4 seconds");
			TimeUnit.SECONDS.sleep(4);
			getEmployeeDetails();

			System.out.println("\n\nSleeping for 4 seconds");
			TimeUnit.SECONDS.sleep(4);
			getEmployeeDetails();

		};
	}
}

Total project structure looks like below.



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

getEmployeeById: Getting the informaiton from internal list
Employee [id=1, firstName=Ram, lastName=Kota]
getEmployeeByFirstName: Getting the informaiton from internal list
Employee [id=4, firstName=Krishna, lastName=Boppana]

Sleeping for 4 seconds
Employee [id=1, firstName=Ram, lastName=Kota]
Employee [id=4, firstName=Krishna, lastName=Boppana]


Sleeping for 4 seconds
Employee [id=1, firstName=Ram, lastName=Kota]
Employee [id=4, firstName=Krishna, lastName=Boppana]


Sleeping for 4 seconds
getEmployeeById: Getting the informaiton from internal list
Employee [id=1, firstName=Ram, lastName=Kota]
getEmployeeByFirstName: Getting the informaiton from internal list
Employee [id=4, firstName=Krishna, lastName=Boppana]
2022-06-29 21:33:13.603  INFO 4091 --- [ionShutdownHook] org.ehcache.core.EhcacheManager          : Cache 'myEmployeeCache' removed from EhcacheManager.

From the output, you can confirm that employee details are served from internal collection for the first time and, till next 10 seconds data is served from the ehcache.

 

You can download complete working application from this link.


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