spring ioc---依赖注入

spring ioc：控制反转，或叫依赖注入

简单的bean装配：

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

import test.HelloWorld;

public class Test {

    public static void main(String[] args) {
        //获取被代理对象的路径
        ApplicationContext ac=new ClassPathXmlApplicationContext("beans.xml");
        
        //获取被代理对象实例
        HelloWorld helloWorld=(HelloWorld)ac.getBean("helloWorld");
        //执行被代理对象的方法
        helloWorld.say();
    }
}

public class HelloWorld {

    public void say(){
        System.out.println("Spring4大爷你好！");
    }
}

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">

    <!-- 被代理的类 -->
    <bean id="helloWorld" class="test.HelloWorld"></bean>
</beans>

 

依赖注入：

1，属性注入；
2，构造函数注入；(通过类型；通过索引；联合使用)
3，工厂方法注入；(非静态工厂，静态工厂)
4，泛型依赖注入；(Spring4 整合Hibernate4 的时候顺带讲)

package entity;

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 + "]";
    }    
}

package factory;

import entity.People;

public class PeopleFactory {

    public People createPeople(){
        People p=new People();
        p.setId(5);
        p.setName("小七");
        p.setAge(77);
        return p;
    }
}

package factory;

import entity.People;

public class PeopleFactory2 {

    public static People createPeople(){
        People p=new People();
        p.setId(8);
        p.setName("小八");
        p.setAge(88);
        return p;
    }
}

　　

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

import entity.People;
public class Test2 {

    public static void main(String[] args) {
        ApplicationContext ac=new ClassPathXmlApplicationContext("beans.xml");
        People people=(People)ac.getBean("people");
        System.out.println(people);
        
        // 属性注入
        People people2=(People)ac.getBean("people2");
        System.out.println(people2);
        
        // 构造方法注入--参数类型
        People people3=(People)ac.getBean("people3");
        System.out.println(people3);
        
        // 构造方法注入--索引
        People people4=(People)ac.getBean("people4");
        System.out.println(people4);
        
        //构造方法注入--索引和类型
        People people5=(People)ac.getBean("people5");
        System.out.println(people5);
        
        // 非静态工厂方法注入
        People people7=(People)ac.getBean("people7");
        System.out.println(people7);
        
        People people8=(People)ac.getBean("people8");
        System.out.println(people8);
    }
}

<?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="people" class="entity.People"></bean>
    <!-- 属性注入 -->
    <bean id="people2" class="entity.People">
        <property name="id" value="1"></property>
        <property name="name" value="张三"></property>
        <property name="age" value="11"></property>
    </bean>
    
    <!-- 有参构造方法注入，通过类型 -->
    <bean id="people3" class="entity.People">
        <constructor-arg type="int" value="2"></constructor-arg>
        <constructor-arg type="String" value="李四"></constructor-arg>
        <constructor-arg type="int" value="22"></constructor-arg>
    </bean>
    
    <!-- 通过索引，参数的顺序 -->
    <bean id="people4" class="entity.People">
        <constructor-arg index="0" value="3"></constructor-arg>
        <constructor-arg index="1" value="王五"></constructor-arg>
        <constructor-arg index="2" value="55"></constructor-arg>
    </bean>
    
    <!-- 通过索引，和类型 -->
    <bean id="people5" class="entity.People">
        <constructor-arg index="0" type="int" value="4"></constructor-arg>
        <constructor-arg index="1" type="String" value="招六"></constructor-arg>
        <constructor-arg index="2" type="int" value="66"></constructor-arg>
    </bean>
    
    <!-- 非静态工厂的bean -->
    <bean id="peopleFactory" class="factory.PeopleFactory"></bean>
    
    <!-- 指定某个工厂的某个非静态方法，创建对象 ->
    <bean id="people7" factory-bean="peopleFactory" factory-method="createPeople"></bean>
  
      <!-- 静态的工厂不需要创建工厂bean -->
      <bean id="people8" class="factory.PeopleFactory2" factory-method="createPeople"></bean>
</beans>