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Spring IoC控制反转与依赖注入
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控制反转(IoC，Inverse of Control)

- Spring对象工厂完成对象的创建
- 对象使用者只需从Spring容器中获取对象即可，无需自己创建

依赖注入(DI，Dependency Injection)

- Spring在创建对象的同时，对其属性赋值

 __________________________________________________________
|                  applicationContext.xml                  |
|----------------------------------------------------------|
|<beans ...>                                               |
|    ...                                                   |
|    <bean id="sc" class="cn.tedu.springioc.beans.Student">|
|        <property name="number" value="1001" /> ----      |
|        <property name="name" value="张飞" />   ----|     |
|        <property name="gender" value="男" />   ----|     |
|        <property name="age" value="20" />      ----|     |
|        ...                                     ----|     |
|    </bean>                                         |     |
|    ...                                             |     |
|</beans>                                            |     |
|____________________________________________________|_____|
                              |                      |
                              v                      |
             __________________________________      |
            |              Spring              |     |
            |----------------------------------|     |
            |  ______________________________  |     |
            | |ClassPathXmlApplicationContext| |     |依赖注入(DI)
            | |______________________________| |     |
            |                 |                |     |
            |                 v                |     |
            |         _________________        |     |
            |        |        sc       |       |     |
            |        |-----------------|       |     |
            |        |    number : 1001| <-----------|
            |        |      name : 张飞| <-----------|
            |        |    gender : 男  | <-----------|
            |        |       age : 20  | <-----------|
            |        |       ...       | <-----------
            |        |_________________|       |
            |__________________________________|
                              |
                              v 控制反转(IoC)
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                         |          |
                         | 业务逻辑 |
                         |__________|