bean注解

1.beans.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
       http://www.springframework.org/schema/mvc
       https://www.springframework.org/schema/mvc/spring-mvc.xsd
       http://www.springframework.org/schema/context
       https://www.springframework.org/schema/context/spring-context-4.2.xsd
       http://www.springframework.org/schema/aop
       https://www.springframework.org/schema/aop/spring-aop-4.2.xsd">

    <!--<bean id="dog" class="com.shao.pojo.Dog"/>-->
    <!--<bean id="cat" class="com.shao.pojo.Cat"/>-->
    <!--&lt;!&ndash;autowire-->
    <!--byName:会从上下文查找，和自己对象set方法值对应的beanid-->
    <!--byType:会找相同类型的-->
    <!--&ndash;&gt;-->
    <!--<bean id="person" class="com.shao.pojo.Person" autowire="byName">-->
    <!--    <property name="name" value="shao"/>-->
    <!--</bean>-->

    <!--注解开发-->
    <!--开启注解的支持-->
    <context:annotation-config/>
    <bean id="dog" class="com.shao.pojo.Dog"/>
    <bean id="cat" class="com.shao.pojo.Cat"/>
    <bean id="person" class="com.shao.pojo.Person"/>

</beans>

2.Person.java

package com.shao.pojo;

import org.springframework.beans.factory.annotation.Autowired;

public class Person {
    private String name;
    //如果autowired中的required为false，说明这个对象可以为null否则不能为空
    @Autowired(required = false)
    private Cat cat;
    @Autowired
    private Dog dog;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Cat getCat() {
        return cat;
    }

    public void setCat(Cat cat) {
        this.cat = cat;
    }

    public Dog getDog() {
        return dog;
    }

    public void setDog(Dog dog) {
        this.dog = dog;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", cat=" + cat +
                ", dog=" + dog +
                '}';
    }
}