[egovFramework 4.1] Hands-on-Guide Ch6 적용해보기 (Dependency Injection)

sliver gun·2024년 7월 20일

di egovframework

egovFramework

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들어가며

Hands-On-Guide 6장 내용의 실습 프로젝트를 만들면서 공부하게 된 내용을 다루었다.

Dependency Injection이란?

객체가 필요한 의존 관계를 외부에서 제공(주입)하는 방식
객체 간의 결합도를 낮추고, 코드의 재사용성을 높임

예시 (Hands-on-guide ch6)

전체적인 Hierarchy는 이런식으로 되어있다.

초기 설정

CustomerService.java

package egovframework.ch6.service;

public interface CustomerService { 
	 String getCustName(String id); 
	 String getCustGrade(String id); 
}

XML-based DI

CustomerXMLDAO.java

package egovframework.ch6.service.impl;

public class CustomerXMLDAO { 
	 public String getCustName(String id) { 
	 return id + " eGovFrame XML"; 
	 } 
	 public String getCustGrade(String id) { 
	 return id + " S XML"; 
	 } 
}

CustomerXMLServiceImpl

package egovframework.ch6.service.impl;

import egovframework.ch6.service.CustomerService;

public class CustomerXMLServiceImpl implements CustomerService { 
	 private CustomerXMLDAO xmlDAO; 
	 public void setCustXMLDAO(CustomerXMLDAO cxmlDAO) { 
		 this.xmlDAO = cxmlDAO; 
	 } 
	 public String getCustName(String id){ 
		return xmlDAO.getCustName(id); 
	 } 
	 public String getCustGrade(String id) { 
		 return xmlDAO.getCustGrade(id); 
	 } 
}

CustomerService 인터페이스에 맞는 CustomerServiceImpl 클래스와 거기에 쓸 CustomerXMLDAO 클래스를 준비한다.

context-customer.xml

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://www.springframework.org/schema/beans 
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd"> 
 
 	<!-- XML-Based Dependency Injection -->
 
 	<bean id="customerXML" class="egovframework.ch6.service.impl.CustomerXMLServiceImpl"> 
 		<property name="custXMLDAO" ref="customerXMLDAO" /> 
 	</bean> 
 
 	<bean id="customerXMLDAO" class="egovframework.ch6.service.impl.CustomerXMLDAO"/>

</beans>

customerXML 빈은 CustomerXMLServiceImpl 클래스의 인스턴스로 생성되고, customerXMLDAO 빈은 egovframework.ch6.service.impl.CustomerXMLDAO 클래스의 인스턴스가 되도록 context-customer.xml을 작성한다.

Annotation-based DI

CustomerAnnotationDAO.java

package egovframework.ch6.service.impl;

import org.springframework.stereotype.Repository;
import egovframework.ch6.service.CustomerService;

@Repository("customerdao") 
public class CustomerAnnotationDAO implements CustomerService { 
	public String getCustName(String id) { 
		return id+" eGovFrame Annotation"; 
	} 
	public String getCustGrade(String id) { 
		return id + " S Annotation"; 
	} 
}

CustomerAnnotationServiceImpl.java

package egovframework.ch6.service.impl;

import javax.annotation.Resource;
import org.springframework.stereotype.Service;
import egovframework.ch6.service.CustomerService;

@Service("customer") 
public class CustomerAnnotationServiceImpl implements CustomerService { 
	@Resource(name="customerdao") 
 	private CustomerAnnotationDAO customerdao;
	
 	public String getCustName(String id) { 
 		return customerdao.getCustName(id);
 	}
 	public String getCustGrade(String id) { 
 		return customerdao.getCustGrade(id); 
 	} 
}

xml 기반 DI와 똑같이 CustomerService 인터페이스에 맞는 CustomerAnnotationServiceImpl 클래스와 거기에 쓸 CustomerAnnotationDAO 클래스를 준비한다.

context-common.xml

<?xml version="1.0" encoding="UTF-8"?> 
 <beans xmlns="http://www.springframework.org/schema/beans" 
 	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 	xmlns:context="http://www.springframework.org/schema/context" 
 	xsi:schemaLocation="http://www.springframework.org/schema/beans
 	http://www.springframework.org/schema/beans/spring-beans-4.0.xsd 
 	http://www.springframework.org/schema/context 
 	http://www.springframework.org/schema/context/spring-context-4.0.xsd"> 
 	
 	<!-- Annotation-Based Dependency Injection -->
 	
 	<context:component-scan base-package="egovframework.ch6"/>
 	
</beans>

context:component-scan을 통해 Annotation 기반 DI를 가능하도록 한다.
이때 패키지 경로를 잘 입력해야한다.

실행시킬 App

CustomerServiceApp.java

package egovframework.ch6.app;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import egovframework.ch6.service.CustomerService;

public class CustomerServiceApp { 
	 public static void main(String[] args) { 
	 // Configuration file location to be read into Spring Container
	 String configLocation = "classpath*:spring/context-*.xml"; 
	 
	 // Create an Application Context using the settings file
	 ApplicationContext context = new ClassPathXmlApplicationContext(configLocation); 
	 
	 // Search for "customerXML" and create dependence.
	 CustomerService CustomerXML =(CustomerService)context.getBean("customerXML"); 
	 
	 System.out.println("[XML]"); 
	 System.out.println("NAME="+CustomerXML.getCustName("1"));
	 System.out.println("GRADE="+CustomerXML.getCustGrade("1")); 
	 // Search for "customer" and create dependence.
	 CustomerService CustomerAnnotation = (CustomerService)context.getBean("customer"); 
	 
	 System.out.println("[Annotation]"); 
	 System.out.println("NAME="+CustomerAnnotation.getCustName("2")); 
	 System.out.println("GRADE="+CustomerAnnotation.getCustGrade("2")); 
}