Spring学习——DI依赖注入

 Spring DI（Dependency Injection，依赖注入）GitHub demo源码

       是指程序运行过程中，如果需要调用另一个对象协助时，无须在代码中创建被调用者，而是依赖于外部的注入。Spring的依赖注入对调用者和被调用者几乎没有任何要求，完全支持对POJO之间依赖关系的管理。

1、基于构造函数的依赖注入

java 类

package com.spring.DI.example;

public class AConstructor {
	private B b;
	public AConstructor(B b){
		System.out.println("AConstructor 构造函数");
		this.b = b;
	}
	
	public void aConstructorSpeack(){
		b.bSpeack();
	}
	
}

Beans1.xml配置文件     使用指定标签声明<constructor-arg ref="B"/>

<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-3.0.xsd">

   <bean id="AConstructor" class="com.spring.DI.example.AConstructor">
   	<!-- 构造函数依赖注入 -->
      <constructor-arg ref="B"/>
   </bean>
   
   <bean id="B" class="com.spring.DI.example.B">
   </bean>

</beans>

2、基于get/set函数的依赖注入

java类：

package com.spring.DI.example;

public class AFunction {
	private B b;
	
	public void setB(B b){
		System.out.println("AFunction 设置B");
		this.b = b;
	}
	public B getB(){
		return b;
	}
	public void aFunctionSpeack(){
		b.bSpeack();
	}
}

Beans2.xml:

<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-3.0.xsd">
    
	<bean id="AFunction" class="com.spring.DI.example.AFunction">
   	<!-- get/set函数依赖注入 -->
      <property name="b" ref="B"/>
   </bean>

   <bean id="B" class="com.spring.DI.example.B">
   </bean>

</beans>

3、基于注入内部bean的依赖注入

<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-3.0.xsd">
    
	<bean id="AFunction" class="com.spring.DI.example.AFunction">
   		<!-- 内部beans依赖注入 -->
      	<property name="b">
      		<bean id="B" class="com.spring.DI.example.B"/>
      	</property>
   </bean>
</beans>

4、java集合依赖注入

java类

package com.spring.DI.example;

import java.util.*;

public class JavaCollection {
	private List list;
	private Set  set;
	private Map  map;
	private Properties properties;
	public List getList() {
		return list;
	}
	public void setList(List list) {
		this.list = list;
	}
	public Set getSet() {
		return set;
	}
	public void setSet(Set set) {
		this.set = set;
	}
	public Map getMap() {
		return map;
	}
	public void setMap(Map map) {
		this.map = map;
	}
	public Properties getProperties() {
		return properties;
	}
	public void setProperties(Properties properties) {
		this.properties = properties;
	}
	
	
}

Beans4.xml

<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-3.0.xsd">
    
	<bean id="JavaCollection" class="com.spring.DI.example.JavaCollection">
   		<!-- list依赖注入 -->
      	<property name="list">
      		<list>
      			<value>list1</value>
      			<value>list2</value>
      			<value>list3</value>
      			<value>list4</value>
      		</list>
      	</property>
      	
      	<!-- set依赖注入 -->
      	<property name="set">
      		<set>
      			<value>set1</value>
      			<value>set2</value>
      			<value>set3</value>
      			<value>set4</value>
      		</set>
      	</property>
      	
      	<!-- map依赖注入 -->
      	<property name="map">
      		<map>
      			<entry key="1" value="map1"/>
      			<entry key="2" value="map2"/>
      			<entry key="3" value="map3"/>
      			<entry key="4" value="map4"/>
      		</map>
      	</property>
      	
      	<!-- property依赖注入 -->
      	<property name="properties">
         <props>
            <prop key="one">prop1</prop>
            <prop key="two">prop2</prop>
            <prop key="three">prop3</prop>
            <prop key="four">prop4</prop>
         </props>
      </property>
   </bean>
</beans>

主程序：SpringMain

package com.spring.DI.example;

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

public class SpringMain {
	public static void main(String[] arg){
		
		System.out.println("-------读取beans1文件---------");
		ApplicationContext context1 = new ClassPathXmlApplicationContext("Beans1.xml");
		
		System.out.println("----构造函数依赖注入------");
		AConstructor ac =(AConstructor) context1.getBean("AConstructor");
		ac.aConstructorSpeack();
		
		System.out.println("-------读取beans2文件---------");
		ApplicationContext context2 = new ClassPathXmlApplicationContext("Beans2.xml");
		
		System.out.println("----get/set依赖注入------");
		AFunction af = (AFunction) context2.getBean("AFunction");
		af.aFunctionSpeack();
		
		System.out.println("-------读取beans3文件---------");
		ApplicationContext context3 = new ClassPathXmlApplicationContext("Beans3.xml");
		
		System.out.println("----get/set依赖注入------");
		AFunction af1 = (AFunction) context3.getBean("AFunction");
		af.aFunctionSpeack();
		
		System.out.println("-------读取beans4文件---------");
		ApplicationContext context4 = new ClassPathXmlApplicationContext("Beans4.xml");
		
		System.out.println("----集合依赖注入------");
		JavaCollection js = (JavaCollection) context4.getBean("JavaCollection");
		System.out.println("list"+js.getList());
		System.out.println("map"+js.getMap());
		System.out.println("set"+js.getSet());
		System.out.println("properties"+js.getProperties());
	}
}