Spring的三种注入方式都是什么？如何选用？

接口注入（不推荐）

gettersetter方式注入（比较常用）

构造器注入（死的应用）

关于getter和setter方式的注入

autowire=&#;defualt&#;

autowire=byName

autowire=&#;bytype&#;

例如有如下两个类需要注入
package orgjia;

public class Order {
private String orderNum;
@SuppressWarnings(&#;unused&#;)
private OrderItem orderitem;

public OrderItem getOrderitem() {
return orderitem;
}

public void setOrderitem(OrderItem orderitem) {
thisorderitem = orderitem;
}

public String getOrderNum() {
return orderNum;
}

public void setOrderNum(String orderNum) {
thisorderNum = orderNum;
}

}
package orgjia;

public class OrderItem {
private String orderdec;

public String getOrderdec() {
return orderdec;
}

public void setOrderdec(String orderdec) {
thisorderdec = orderdec;
}
}

getter&&setter方式第一种注入
<?xml version=&#;&#; encoding=&#;UTF&#;?>
<!DOCTYPE beans PUBLIC &#;//SPRING//DTD BEAN//EN&#; &#;;>

<beans>
<bean id=&#;orderItem&#;>
<property name=&#;orderdec&#; value=&#;item&#;></property>
</bean>
<bean id=&#;order&#; >
<!&#;&#;注入变量 名字必须与类中的名字一样&#;&#;>
<property name=&#;orderNum&#; value=&#;order&#;></property>
<！&#;注入对象 名字为orderitem所属的类的应用id为orderItem&#;>
<property name=&#;orderitem&#; ref=&#;orderItem&#;></property>

&#;></bean>

</beans>
getter&&setter方式第二种注入 byName
<?xml version=&#;&#; encoding=&#;UTF&#;?>
<!DOCTYPE beans PUBLIC &#;//SPRING//DTD BEAN//EN&#; &#;;>
<beans>
<!&#;此时的id就必须与Orderjava中所定义的OrderItem的对象名称一样了不然就会找不到&#;>
<bean id=&#;orderitem&#;>
<property name=&#;orderdec&#; value=&#;item&#;></property>
</bean>
<bean id=&#;order&#; autowire=&#;byName&#;>
<property name=&#;orderNum&#; value=&#;order&#;></property>
</bean>
</beans>
getter&&setter方式第三种注入byType
<?xml version=&#;&#; encoding=&#;UTF&#;?>
<!DOCTYPE beans PUBLIC &#;//SPRING//DTD BEAN//EN&#; &#;;>
<beans>
<!&#;按照byType注入则就与id没有关系可以随便定义id ！！！但是不能出现多个此类的id&#;>
<bean id=&#;orderitdfadafaem&#;>
<property name=&#;orderdec&#; value=&#;item&#;></property>
</bean>
<bean id=&#;order&#; autowire=&#;byType&#;>
<property name=&#;orderNum&#; value=&#;order&#;></property>
</bean>
</beans>