峰Spring4学习（5）bean之间的关系和bean的作用范围

一、bean之间的关系：

1）继承：

People.java实体类：

package com.cy.entity;

public class People {
    private int id;
    private String name;
    private int age;
    private String className;

    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;
    }
    public String getClassName() {
        return className;
    }
    public void setClassName(String className) {
        this.className = className;
    }

    @Override
    public String toString() {
        return "People [id=" + id + ", name=" + name + ", age=" + age
                + ", className=" + className + "]";
    }

}

beans.xml配置文件：

<?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"
        default-autowire="byName">

    <bean id="abstractPeople" class="com.cy.entity.People" abstract="true">
        <property name="className" value="高三(1)班"></property>
        <property name="age" value="18"></property>
    </bean>

     <bean id="zhangsan" parent="abstractPeople">
         <property name="id" value="1"></property>
         <property name="name" value="张三"></property>
     </bean>

     <bean id="lisi" parent="abstractPeople">
         <property name="id" value="2"></property>
         <property name="name" value="李四"></property>
         <property name="age" value="20"></property>
     </bean>
</beans>

测试代码：

@Before
    public void setUp() throws Exception {
         ac=new ClassPathXmlApplicationContext("beans.xml");
    }

    @Test
    public void test() {
        People zhangsan = (People) ac.getBean("zhangsan");
        System.out.println(zhangsan); 

        People lisi = (People) ac.getBean("lisi");
        System.out.println(lisi);
    }

2)依赖：

spring中加载bean的方式默认是按照bean配置的顺序加载的；

例如，查看zhangsan之前，必须要有权限，要先获取权限；

People.java:

package com.cy.entity;

public class People {
    private int id;
    private String name;
    private int age;
    private String className;

    public People(){
        System.out.println("People初始化..");
    }

    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;
    }
    public String getClassName() {
        return className;
    }
    public void setClassName(String className) {
        this.className = className;
    }

    @Override
    public String toString() {
        return "People [id=" + id + ", name=" + name + ", age=" + age
                + ", className=" + className + "]";
    }

}

com.cy.service.Authority:

package com.cy.service;

public class Authority {
    public Authority(){
        System.out.println("获取权限..");
    }
}

beans.xml配置：

<?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"
        default-autowire="byName">

    <bean id="abstractPeople" class="com.cy.entity.People" abstract="true">
        <property name="className" value="高三(1)班"></property>
        <property name="age" value="18"></property>
    </bean>

     <bean id="zhangsan" parent="abstractPeople">
         <property name="id" value="1"></property>
         <property name="name" value="张三"></property>
     </bean>

     <bean id="lisi" parent="abstractPeople" depends-on="authority">
         <property name="id" value="2"></property>
         <property name="name" value="李四"></property>
         <property name="age" value="20"></property>
     </bean>

     <bean id="authority" class="com.cy.service.Authority"></bean>
</beans>

测试代码：

@Test
    public void test() {
        People zhangsan = (People) ac.getBean("zhangsan");
        System.out.println(zhangsan); 

        People lisi = (People) ac.getBean("lisi");
        System.out.println(lisi);
    }

配置了depend on属性之后，加载lisi这个bean必须要先加载authority这个bean，所以bean的加载顺序变了，打印如下：

3）引用：

就是这样子：

<bean id="lisi" parent="abstractPeople">
        <property name="id" value="2"></property>
        <property name="name" value="李四"></property>
        <property name="age" value="20"></property>
        <property name="dog" ref="dog"></property>
    </bean>

二、bean作用范围：

默认是单例的：

<bean id="dog" class="com.java1234.entity.Dog" scope="singleton">
　　<property name="name" value="jack"></property>
</bean>

多例的配置：

<bean id="dog" class="com.java1234.entity.Dog" scope="prototype">
　　<property name="name" value="jack"></property>
</bean>