Spring--IOC容器——对象依赖关系（注解）
2017-06-25 本文已影响113人
Mr_欢先生
注解方式可以简化spring的IOC容器的配置!
使用注解步骤：
- 1）先引入context名称空间
xmlns:context="http://www.springframework.org/schema/context" - 2）开启注解扫描
<context:component-scan base-package="cn.itcast.e_anno2"></context:component-scan> - 3）使用注解
通过注解的方式，把对象加入ioc容器。
创建对象以及处理对象依赖关系，相关的注解：
@Component指定把一个对象加入IOC容器
@Repository作用同@Component； 在持久层使用
@Service作用同@Component； 在业务逻辑层使用
@Controller作用同@Component； 在控制层使用
@Resource属性注入
总结：
1） 使用注解，可以简化配置，且可以把对象加入IOC容器,及处理依赖关系(DI)
2） 注解可以和XML配置一起使用。
方法一
注解：
<?xml version="1.0" encoding="utf-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd " >
<!--开启注解扫描-->
<context:component-scan base-package="com.huan"></context:component-scan>
</beans>
UserDao.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Component("userDao") //相当于 bean.xml[<bean id =userDao class="com.huan.BeanTest.UserDao">]
public class UserDao {
public void save(){
System.out.println("db:操作数据库");
}
}
UserService.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Component("userService")//userService对象，注入到ioc容器
public class UserService {
//从IOC容器中找到userDao对象，注入到当前字段
/**
* <bean id =userDao class="com.huan.BeanTest.UserDao">
* <property name = "userDao" ref ="userDao" ></property> 相当于 @Resource(name = "userDao")
*
* </bean>
*/
@Resource(name = "userDao")
private UserDao userDao;
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
public void save(){
userDao.save();
}
}
UserAction.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Component("userAction")
public class UserAction {
@Resource(name = "userService")
private UserService userService;
public void execute(){
userService.save();
}
}
创建user对象
@Test
public void test2(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("Spring/applicationContext.xml");
UserAction userAction = (UserAction) applicationContext.getBean("userAction");
userAction.execute();
方法二
注解：
<?xml version="1.0" encoding="utf-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd " >
<!--开启注解扫描-->
<context:component-scan base-package="com.huan"></context:component-scan>
</beans>
UserDao.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Component
public class UserDao {
public void save(){
System.out.println("db:操作数据库zui");
}
}
UserService.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Component
public class UserService {
@Resource//根据类型查找·[在容器中，该类型只有一个变量]
private UserDao userDao;
public void save(){
userDao.save();
}
}
UserAction.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Component
public class UserAction {
@Resource
private UserService userService;
public void execute(){
userService.save();
}
}
创建user对象
@Test
public void test2(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("Spring/applicationContext.xml");
UserAction userAction = (UserAction) applicationContext.getBean("userAction");
userAction.execute();
方法三
注解：
<?xml version="1.0" encoding="utf-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd " >
<!--开启注解扫描-->
<context:component-scan base-package="com.huan"></context:component-scan>
</beans>
UserDao.java
package com.huan.BeanTest;
import org.springframework.stereotype.Repository;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Repository
public class UserDao {
public void save(){
System.out.println("db:操作数据库zui");
}
}
UserService.java
package com.huan.BeanTest;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Service
public class UserService {
@Resource
private UserDao userDa;
public void save(){
userDa.save();
}
}
UserAction.java
package com.huan.BeanTest;
import org.springframework.stereotype.Controller;
import javax.annotation.Resource;
/**
* Created by 马欢欢 on 2017/6/24.
*/
@Controller
public class UserAction {
@Resource
private UserService userService;
public void execute(){
userService.save();
}
}
创建user对象
@Test
public void test2(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("Spring/applicationContext.xml");
UserAction userAction = (UserAction) applicationContext.getBean("userAction");
userAction.execute();
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