Spring使用@Autowired注解自动装配

注 @Autowired注解是通过匹配数据类型自动装配Bean

1. Beans

2.注册AutowiredAnnotationBeanPostProcessor
要启用@Autowired，必须注册“AutowiredAnnotationBeanPostProcessor’，你可以用两种方式做到这一点：

1. Include <context:annotation-config

<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">
    <context:annotation-config />
    <bean id="CustomerBean" class="com.yiibai.common.Customer">
        <property name="action" value="buy" />
        <property name="type" value="1" />
    </bean>
    <bean id="PersonBean" class="com.yiibai.common.Person">
        <property name="name" value="yiibai" />
        <property name="address" value="address ABC" />
        <property name="age" value="29" />
    </bean>
</beans>

1. 包含 AutowiredAnnotationBeanPostProcessor

<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-2.5.xsd">
<bean 
class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
    <bean id="CustomerBean" class="com.yiibai.common.Customer">
        <property name="action" value="buy" />
        <property name="type" value="1" />
    </bean>
    <bean id="PersonBean" class="com.yiibai.common.Person">
        <property name="name" value="yiibai" />
        <property name="address" value="address ABC" />
        <property name="age" value="29" />
    </bean>
</beans>

1. @Autowired示例

1. @Autowired setter 方法
package com.yiibai.common;
import org.springframework.beans.factory.annotation.Autowired;
public class Customer 
{
    private Person person;
    private int type;
    private String action;
    //getter and setter methods
    @Autowired
    public void setPerson(Person person) {
        this.person = person;
    }
}
2. @Autowired 构造方法
package com.yiibai.common;
import org.springframework.beans.factory.annotation.Autowired;
public class Customer 
{
    private Person person;
    private int type;
    private String action;
    //getter and setter methods
    @Autowired
    public Customer(Person person) {
        this.person = person;
    }
}
3. @Autowired 字段
package com.yiibai.common;
import org.springframework.beans.factory.annotation.Autowired;
public class Customer 
{
    @Autowired
    private Person person;
    private int type;
    private String action;
    //getter and setter methods
}

依赖检查

要解决这个问题，可以通过 @Autowired 的“required”属性设置为false来禁用此检查功能。
package com.yiibai.common;
import org.springframework.beans.factory.annotation.Autowired;
public class Customer 
{
    @Autowired(required=false)
    private Person person;
    private int type;
    private String action;
    //getter and setter methods
}

@Qualifier

<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">
    <context:annotation-config />
    <bean id="CustomerBean" class="com.yiibai.common.Customer">
        <property name="action" value="buy" />
        <property name="type" value="1" />
    </bean>
    <bean id="PersonBean1" class="com.yiibai.common.Person">
        <property name="name" value="yiibai-1" />
        <property name="address" value="address-1" />
        <property name="age" value="29" />
    </bean>
    <bean id="PersonBean2" class="com.yiibai.common.Person">
        <property name="name" value="yiibai-2" />
        <property name="address" value="address-2" />
        <property name="age" value="28" />
    </bean>
</beans>

可以使用 @Qualifier 自动装配一个特定的 bean
package com.yiibai.common;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
public class Customer 
{
    @Autowired
    @Qualifier("PersonBean1")
    private Person person;
    private int type;
    private String action;
    //getter and setter methods
}