Inversion of Control:
After using the Spring Framework object is not created by the caller, but created by the Spring container
Spring container will be responsible for the relationship between the program control rather than code directly controlled by the caller program
Such control is transferred from the application to the Spring container, control reversal took place, this is the Spring Inversion of Control
Process to obtain a dependent object is reversed, after reversal control, the process of obtaining their dependent objects from the active management becomes injected from the IOC container
Thus, "Inversion of Control," also called "DI" (Dependency Injection) short (DI) called dependency injection, that is, the IOC container during operation
Some of the dynamic dependency injection into an object
Therefore, dependency injection (DI) and reverse control (IOC) are described from different angles of the same thing, that refers to the introduction of IOC container
Manner using dependency injection, decoupling between objects
Example code:
1, and the set of common data type injection
[1] Create a user entity class provides methods and set construction and toString
[2] write configuration file
<bean id="user" class="com.bdqn.cn.pojo.User">
<!-- 通过构造注入 -->
<!-- <constructor-arg index="0" value="张三"/>
<constructor-arg index="1">
<list>
<value>list1</value>
<value>list2</value>
</list>
</constructor-arg>
<constructor-arg index="2">
<map>
<entry key="hhh" value="哈哈哈"/>
<entry key="zzz" value="啧啧啧"/>
<entry key="bbb" value="不不不"/>
</map>
</constructor-arg>
<constructor-arg index="3">
<set>
<value>张三</value>
<value>李四</value>
<value>王五</value>
</set>
</constructor-arg>
<constructor-arg index="4">
<array>
<value>aaaaaaaa</value>
<value>bbbbbbbb</value>
</array>
</constructor-arg> -->
<!-- 通过setter方法注入参数 -->
<property name="username" value="赵云" />
<property name="list">
<list>
<value>看书</value>
<value>学习</value>
</list>
</property>
<property name="map">
<map>
<entry key="guangshou" value="广州" />
<entry key="shanghai" value="上海" />
<entry key="shenzhen" value="深圳" />
</map>
</property>
<property name="set">
<set>
<value>关羽</value>
<value>张飞</value>
<value>赵云</value>
<value>马超</value>
<value>黄忠</value>
</set>
</property>
<property name="array">
<array>
<value>aaaaaaaa</value>
<value>bbbbbbbb</value>
</array>
</property>
</bean>
[3] write test classes
2, target injection
[1] create the interface and implementation class
[2] create a business layer
public class UserServiceImpl the implements UserService {
// here embodied not only declared
Private UserDao userDao;
// to set mode parameters passed userDao
/ * public void setUserDAO (UserDao userDao) {
this.userDao = userDao;
} * /
// constructor in the form of
public UserServiceImpl (UserDao userDao) {
Super ();
the this .userDao = userDao;
}
@Override
public void say () {
the this .userDao.say ();
System.out.println ("UserServiceImpl...");
}
}
【3】编写配置文件
【4】编写测试类
