Spring -08 -自动注入 -byName/byType/constructor -全局使用default-autowire=” byName"

1.在Spring 配置文件中对象名和ref=”id”id 名相同使用自动注入,可以不配置<property/>
2.两种配置办法
　　　2.1在<bean>中通过 autowire=”” 配置,只对这个<bean>生效
　　  2.2在<beans>中通过 default-autowire=””配置,表当当前文件中所有<bean>都是全局配置内容
3.autowire=”” 的可取值
　　3.1default: 默认值,根据全局 default-autowire=””值. 默认全局和局部都没有配置情况下,相当于no.
　　3.2no: 不自动注入

public class People {   //类的关系
    private Teacher teacher;
}

    <bean id="teacher" class="com.test.Teacher"></bean>
    <bean id="people" class="com.test.People" autowire="default">
        <property name="teacher" ref="teacher"></property>
    </bean>

    <bean id="teacher" class="com.test.Teacher"></bean>
    <bean id="people" class="com.test.People">
        <property name="teacher" ref="teacher"></property>
    </bean>

　　3.3byName: 通过名称自动注入.在Spring 容器中寻找缺省的类的同名的Id

 <bean id="teacher" class="com.test.Teacher"></bean>
    <bean id="people" class="com.test.People" autowire="byName"></bean>

　　3.4byType: 根据类型注入.
　　　　3.4.1spring 容器中不可以出现两个相同类型的<bean>

   <bean id="teacher123" class="com.test.Teacher"></bean>
    <bean id="people" class="com.test.People" autowire="byType"></bean>　　

     输出: People{teacher=com.test.Teacher@6093dd95}

  <bean id="teacher123" class="com.test.Teacher"></bean>
    <bean id="teacher124" class="com.test.Teacher"></bean>
    <bean id="people" class="com.test.People" autowire="byType"></bean>

输出报错信息:expected single matching bean but found 2: teacher123,teacher124

　　3.5constructor: 根据构造方法注入.
　　　　3.5.1提供对应参数的构造方法(构造方法参数中包含注入对戏那个)

    <bean id="teacher123" class="com.test.Teacher"></bean>
    <bean id="teacher" class="com.test.Teacher"></bean>
<!--保证constructor的入口参数和id的名称一致 -->
    <bean id="people" class="com.test.People" autowire="constructor"></bean>

public class People {
    private Teacher teacher;

    public People() {
    }

    public People(Teacher teacher123) {
        this.teacher = teacher123;
    }
}

　　建议: 在全局使用default-autowire=” byName "