IOC(十一)

自动装配: 根据指定装配规则(属性名称或属性类型), Spring自动将匹配的属性值进行注入

实例:

byName

创建Department类:

public class Department {
    @Override
    public String toString() {
        return "Department{}";
    }
}

创建Employee类:

public class Employee {
    private Department dept;

    public void setDept(Department dept) {
        this.dept = dept;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "dept=" + dept +
                '}';
    }
}

xml配置:(设置autowire="byName"后bean会自动根据属性名去注入相同id的对象)

<?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">

    <bean id="dept" class="com.ryan.spring5.autowire.Department"></bean>
    <bean id="emp" class="com.ryan.spring5.autowire.Employee" autowire="byName"></bean>
</beans>

测试:

Employee{dept=Department{}}

byType

修改xml文件设置: 

autowire="byType"

结果相同, 但设置autowire="byType"时, xml中该类型的bean只能有一个, 否则会报错: