Spring 依賴注入四種方式
阿新 • • 發佈:2019-02-03
紙上得來終覺淺
1.構造器注入
AnimalDao:
package com.roadArchitectWeb.dao;
public interface AnimalDao {
/*所有動物有一個說話的方法*/
public void say();
}
CatDaoImpl:
AnimalMain:package com.roadArchitectWeb.dao; public class CatDaoImpl implements AnimalDao{ /*這個時候並沒有值,會有xml檔案注入*/ private String says; public void say(){ System.out.println("CatDaoImpl.say():"+says); } /*帶引數,方便利用構造器進行注入*/ public CatDaoImpl(String says){ this.says=says; } }
ApplicationContext.xml:package com.roadArchitectWeb.dao; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; class AnimalSay1{ private AnimalDao animalDao; public void setAnimalDao(AnimalDao animalDao) { this.animalDao = animalDao; } public void Say(){ animalDao.say(); } public AnimalSay1(AnimalDao animalDao){ this.animalDao=animalDao; } } public class AnimalMain { public static void main(String[] args) { /*建立Spring的IOX容器物件*/ ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); /*從IOC容器中獲取Bean例項*/ AnimalSay1 animalSay1 = (AnimalSay1)ctx.getBean("AnimalSay1"); /*呼叫其中的say方法*/ animalSay1.Say(); } }
輸出結果:<?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.xsd"> <bean id="CatDaoImpl" class="com.roadArchitectWeb.dao.CatDaoImpl"> <constructor-arg value="喵喵喵"></constructor-arg> </bean> <bean id="AnimalSay1" class="com.roadArchitectWeb.dao.AnimalSay1"> <constructor-arg ref="CatDaoImpl"></constructor-arg> </bean> </beans>
CatDaoImpl.say():喵喵喵
所謂構造器注入,即類中有一個構造方法,同時在配置檔案中利用該構造方法進行注入,上述例子用了兩次構造器注入。
2.setter方法注入
上一篇文章是setter方法的具體應用。
3.靜態工廠
既然是靜態工廠方式注入,首先新建一個工廠用於獲取CatDaoImpl例項:
package com.roadArchitectWeb.dao;
public class DaoFactory {
/*靜態工廠方法*/
public static AnimalDao getStaticInstance(String says){
return new CatDaoImpl(says);
}
}
applicationContext.xml變為:
<?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.xsd">
<bean id="CatDaoImpl" class="com.roadArchitectWeb.dao.CatDaoImpl">
<constructor-arg value="喵喵喵"></constructor-arg>
</bean>
<bean id="AnimalSay1" class="com.roadArchitectWeb.dao.AnimalSay1">
<constructor-arg ref="CatDaoImpl"></constructor-arg>
</bean>
<bean id="DaoFactory" class="com.roadArchitectWeb.dao.DaoFactory" factory-method="getStaticInstance">
<constructor-arg value="哇哇哇"></constructor-arg>
</bean>
</beans>
AnimalMain修改為:
package com.roadArchitectWeb.dao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
class AnimalSay1{
private AnimalDao animalDao;
public void setAnimalDao(AnimalDao animalDao) {
this.animalDao = animalDao;
}
public void Say(){
animalDao.say();
}
public AnimalSay1(AnimalDao animalDao){
this.animalDao=animalDao;
}
}
public class AnimalMain {
public static void main(String[] args) {
/*建立Spring的IOX容器物件*/
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
/*從IOC容器中獲取Bean例項*/
AnimalSay1 animalSay1 = (AnimalSay1)ctx.getBean("AnimalSay1");
/*呼叫其中的say方法*/
animalSay1.Say();
AnimalDao animalDao = (AnimalDao)ctx.getBean("DaoFactory");
animalDao.say();
}
}
結果為:
CatDaoImpl.say():喵喵喵
CatDaoImpl.say():哇哇哇
所謂靜態工廠,不同於建構函式注入和setter方法注入,它通過factory-method指定方法,從而獲得例項的引用。
4.例項工廠
同靜態工廠相同,只是新增一個工廠DaoInstanceFactory:
package com.roadArchitectWeb.dao;
public class DaoInstanceFactory {
/*例項工廠方法*/
public AnimalDao getStaticInstance(String says){
return new CatDaoImpl(says);
}
}
applicationContext.xml變為:<?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.xsd">
<bean id="CatDaoImpl" class="com.roadArchitectWeb.dao.CatDaoImpl">
<constructor-arg value="喵喵喵"></constructor-arg>
</bean>
<bean id="AnimalSay1" class="com.roadArchitectWeb.dao.AnimalSay1">
<constructor-arg ref="CatDaoImpl"></constructor-arg>
</bean>
<bean id="DaoFactory" class="com.roadArchitectWeb.dao.DaoFactory" factory-method="getStaticInstance">
<constructor-arg value="哇哇哇"></constructor-arg>
</bean>
<bean id="DaoInstanceFactory" class="com.roadArchitectWeb.dao.DaoFactory" factory-method="getStaticInstance">
<constructor-arg value="嗚嗚嗚"></constructor-arg>
</bean>
</beans>
AnimalMain修改為:
package com.roadArchitectWeb.dao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
class AnimalSay1{
private AnimalDao animalDao;
public void setAnimalDao(AnimalDao animalDao) {
this.animalDao = animalDao;
}
public void Say(){
animalDao.say();
}
public AnimalSay1(AnimalDao animalDao){
this.animalDao=animalDao;
}
}
public class AnimalMain {
public static void main(String[] args) {
/*建立Spring的IOX容器物件*/
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
/*從IOC容器中獲取Bean例項*/
AnimalSay1 animalSay1 = (AnimalSay1)ctx.getBean("AnimalSay1");
/*呼叫其中的say方法*/
animalSay1.Say();
AnimalDao animalDao = (AnimalDao)ctx.getBean("DaoFactory");
animalDao.say();
AnimalDao animalDao2 = (AnimalDao)ctx.getBean("DaoInstanceFactory");
animalDao2.say();
}
}
結果為:
CatDaoImpl.say():喵喵喵
CatDaoImpl.say():哇哇哇
CatDaoImpl.say():嗚嗚嗚