Spring的依赖注入可以是我们不需要去管理bean，网上看到一个回答很精辟：
现在你需要买一把锤子:
1、自己做一把，解释成java就是，调用者创建被调用着，也就是自己去创造一个造锤子的方法，然后自己调用；
2、自己找到生产锤子的工厂，然后问工厂买。就是工厂模式；
3、可以打电话给商店，让商店给自己送一把锤子过来，这就是sping的依赖注入;
第一种方法调用者创建被调用者，两者之前无法实现松耦合；
第二种方法调用者无须关心被调用者具体实现过程，只需要找到符合某种标准(接口)的实例，即可使用；
第三种调用者无须自己定位工厂，程序运行到需要被调用者时，系统自动提供被调用者实例。调用者和被调用者通过spring管理。他们的关系由spring维护
model
package com.hongcong.model;
public class People {
private int id;
private String name;
private int age;
public People() {
super();
// TODO Auto-generated constructor stub
}
public People(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "People [id=" + id + ", name=" + name + ", age=" + age + "]";
}
}
beans.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.xsd"> <!--属性注入 -->
<bean id="people1" class="com.hongcong.model.People">
<property name="id" value="1"/>
<property name="name" value="小一"/>
<property name="age" value="11"/>
</bean> <!-- 构造方法类型注入 -->
<bean id="people2" class="com.hongcong.model.People">
<constructor-arg type="int" value="2"></constructor-arg>
<constructor-arg type="String" value="小二"></constructor-arg>
<constructor-arg type="int" value="22"></constructor-arg>
</bean> <!-- 构造方法顺序注入 -->
<bean id="people3" class="com.hongcong.model.People">
<constructor-arg index="0" value="3"></constructor-arg>
<constructor-arg index="1" value="小三"></constructor-arg>
<constructor-arg index="2" value="33"></constructor-arg>
</bean>
<!-- 工厂注入 -->
<bean id="peopleFactory" class="com.hongcong.factory.PeopleFactory"></bean>
<bean id="people4" factory-bean="peopleFactory" factory-method="CreatePeople"></bean>
<bean id="people5" class="com.hongcong.factory.PeopleFactory" factory-method="CreatePeopleByStatic"></bean>
</beans>
执行类
package com.hongcong.test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.hongcong.model.People;
public class test {
public static void main(String[] args) {
ClassPathXmlApplicationContext ca = new ClassPathXmlApplicationContext("beans.xml");
//属性注入
People people1 = (People)ca.getBean("people1");
System.out.println(people1);
//构造方法type注入
People people2 = (People)ca.getBean("people2");
System.out.println(people2);
//构造方法顺序注入
People people3 = (People)ca.getBean("people3");
System.out.println(people3);
//非静态工厂
People people4 = (People)ca.getBean("people4");
System.out.println(people4);
//静态工厂注入
People people5 = (People)ca.getBean("people5");
System.out.println(people5);
}
}
工厂
package com.hongcong.factory;
import com.hongcong.model.People;
public class PeopleFactory {
public People CreatePeople(){
People people = new People();
people.setId(4);
people.setName("小四");
people.setAge(44);
return people;
}
public static People CreatePeopleByStatic(){
People people = new People();
people.setId(5);
people.setName("小五");
people.setAge(55);
return people;
}
}