26 Spring由名称(Name)自动装配

在Spring中，“按名称自动装配”是指，如果一个bean的名称与其他bean属性的名称是一样的，那么将自动装配它。
例如，如果“customer” bean公开一个“address”属性，Spring会找到“address” bean在当前容器中，并自动装配。如果没有匹配找到，那么什么也不做。
你可以通过 autowire="byName" 自动装配像下面这样：

<!-- customer has a property name "address" -->
<bean id="customer" class="com.gp6.autoAssemblyBean.Customer" autowire="byName" />

<bean id="address" class="com.gp6.autoAssemblyBean.Address" >
    <property name="fulladdress" value="YiLong Road, CA 188" /> 
</bean>

看看Spring自动装配的完整例子。

1. Beans

这里有两个 beans, 分别是：customer 和 address.

package com.gp6.autoAssemblyBean.name;

public class Address {
    private String fulladdress;

    public String getFulladdress() {
        return fulladdress;
    }

    public void setFulladdress(String fulladdress) {
        this.fulladdress = fulladdress;
    }
}

package com.gp6.autoAssemblyBean.name;

public class Customer {
    private Address address;

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

2. Spring 装配

通常情况下，您明确装配Bean，这样通过 ref 属性：

<!-- 通过ref手动装配-->
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-2.5.xsd">

    <bean id="customer" class="com.gp6.autoAssemblyBean.name.Customer" >
        <property name="address" ref="address" />
    </bean>
    
    <bean id="address" class="com.gp6.autoAssemblyBean.name.Address" >
        <property name="fulladdress" value="YiLong Road, CA 188" /> </bean>
    
</beans>

输出

YiLong Road, CA 188

使用按名称启用自动装配，你不必再声明属性标记。只要在“address” bean是相同于“customer” bean 的“address”属性名称，Spring会自动装配它。

<!-- 通过类型Name装配 -->
 <beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-2.5.xsd">

    <bean id="customer" class="com.gp6.autoAssemblyBean.name.Customer" autowire="byName" />
    
    <bean id="address" class="com.gp6.autoAssemblyBean.name.Address" >
        <property name="fulladdress" value="YiLong Road, CA 188" /> 
    </bean>
    
</beans>