关于Spring的注入方式

spring的三种注入方式：

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1. 接口注入（不推荐）
2. getter，setter方式注入（比较常用）
3. 构造器注入（死的应用）

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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

1 package org.jia;
2
3 publicclass Order {
4 private String orderNum;
5 @SuppressWarnings("unused")
6 private OrderItemorderitem;
7
8 public OrderItem getOrderitem() {
9 return orderitem;
10 }
11
12 publicvoid setOrderitem(OrderItem orderitem) {
13 this.orderitem= orderitem;
14 }
15
16 public String getOrderNum() {
17 return orderNum;
18 }
19
20 publicvoid setOrderNum(String orderNum) {
21 this.orderNum= orderNum;
22 }
23
24 }
25 package org.jia;
26
27 publicclass OrderItem {
28 private String orderdec;
29
30 public String getOrderdec() {
31 return orderdec;
32 }
33
34 publicvoid setOrderdec(String orderdec) {
35 this.orderdec= orderdec;
36 }
37 }
38

getter&&setter方式第一种注入：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
<bean id="orderItem" class="org.jia.OrderItem">
<property name="orderdec" value="item00001"></property>
</bean>
<bean id="order" class="org.jia.Order">
<!-----注入变量 名字必须与类中的名字一样------->
<propertyname="orderNum" value="order000007"></property>
<！--注入对象 名字为orderitem，所属的类的应用id为orderItem-->
<propertyname="orderitem" ref="orderItem"></property>

--></bean>


</beans>

getter&&setter方式第二种注入： byName

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<!--此时的id就必须与Order.java中所定义的OrderItem的对象名称一样了，不然就会找不到-->
<beanid="orderitem" class="org.jia.OrderItem">
<property name="orderdec" value="item00001"></property>
</bean>
<bean id="order" class="org.jia.Order" autowire="byName">
<property name="orderNum" value="order000007"></property>
</bean>
</beans>

getter&&setter方式第三种注入：byType

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<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-->
<beanid="orderitdfadafaem" class="org.jia.OrderItem">
<property name="orderdec" value="item00001"></property>
</bean>
<bean id="order" class="org.jia.Order" autowire="byType">
<property name="orderNum" value="order000007"></property>
</bean>
</beans>

关于构造器的注入：

autowire="constructor"
需要在Order.java中加入一个构造器
public Order(OrderItem item ){ orderitem = item; }

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="orderItem" class="org.jia.OrderItem">
<property name="orderdec" value="item00001"></property>
</bean>
<bean id="order" class="org.jia.Order" autowire="constructor">
<property name="orderNum" value="order000007"></property>
</bean>
</beans>