Spring基于注解的开发
注解就是一个类，使用@注解名称，用于取代xml配置文件。
（一）普通注解：@Component("id") 取代 <beanid="" class=""> 【见例一】
（二）web开发提供三个注解： 【见例二】
（1）@Repository ：dao层
（2）@Service：service层
（3）@Controller：web层
（三）依赖注入（给私有字段或者是setter方法设值）
（1）普通值 @Value("")
（2）引用值：
按照类型@Autowired，
按照名称@Autowired
@Qualifier("名称")
按照名称 @Resource("名称")
（四）生命周期 【见例三】
初始化：@PostConstruct
销毁：@PreDestroy
（五）作用域：@Scope("prototype")多例
【注意】使用注解的前提，添加命名空间，让Spring扫描含有注解的类。
<beansxmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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">
<!--组件扫描，扫描含有注解的类 -->
<context:component-scanbase-package="？"></context:component-scan>
例一：使用@Component("id") 取代<bean id="" class="">
步骤：编写User接口，编别UserImlp实现类，编写xml，编写测试类。
public interface User {
public void add();
}
@Component("UserImpleId")
public class UserImple implements User {
@Override
public void add() {
// TODO Auto-generated method stub
System.out.println("annotion addUser");
}
}
<?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: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">
<!-- 组件扫描，扫描含有注解的类 -->
<context:component-scan base-package="com.Lily.SpringLearning.f_annotation_a_component"></context:component-scan>
</beans>
public class Test {
@org.junit.Test
public void test() {
String xmlPath = "com/Lily/SpringLearning/f_annotation_a_component/beans.xml";
ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
User u = (User) applicationContext.getBean("UserImpleId");
u.add();
}
}
例二：web开发的三个注解
步骤：
1、编写my_service接口
2、编写 my_dao接口
3、编写my_daoImpl实现类，并注解@Repository("mydaoId")
4、编程my_serviceImpl实现类，并提供注解@Service，在调用dao的方法前面加上注解：@Autowired @Qualifier("mydaoId ") 【按照名称注入】
5、编写action类，并提供注解@Controller("ActionId") 在调用service服务前 注解@Autowired
6、编写xml，扫描包。
7、编写测试类，这里getBean需要get的是action的Id。
public interface my_Service {
void add();
}
public interface my_dao {
void save();
}
@Repository("mydaoid")
public class my_daoImpl implements my_dao {
/* (non-Javadoc)
* @see com.Lily.SpringLearning.f_annotation_b_web.my_dao#save()
*/
@Override
public void save() {
// TODO Auto-generated method stub
System.out.println("Dao save() work! ");
}
}
@Service
public class my_serviceImpl implements my_Service {
private my_dao dao;
@Autowired
@Qualifier("mydaoid")
public void setDao(my_dao dao) {
this.dao = dao;
}
@Override
public void add() {
dao.save();
}
}
@Controller("myactionId")
public class my_Aciton {
@Autowired
private my_Service s;
public void DoAction(){
s.add();
}
}
<?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: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">
<!-- 组件扫描，扫描含有注解的类 -->
<context:component-scan base-package="com.Lily.SpringLearning.f_annotation_b_web"></context:component-scan>
</beans>
public class Test {
@org.junit.Test
public void test() {
String xmlpath="com/Lily/SpringLearning/f_annotation_b_web/beans.xml";
ApplicationContext ap=new ClassPathXmlApplicationContext(xmlpath);
my_Aciton ac=(my_Aciton) ap.getBean("myactionId");
ac.DoAction();
}}
例三 生命周期：初始化和销毁
步骤：
1、写一个User接口
2、写UserImple实现类，并在类名前加上注解@Service("userId") ，然后在初始化类前面加上注解@PostConstruct，在销毁方法前加上注解 @PreDestroy
3、编写xml扫描组件
4、编写测试类，【注意】这里的测试类的getBean方法和以前的不太一样，要用类.class来获得！
public interface User {
public void add();
}
@Service("UserId")
public class UserImpl implements User {
/* (non-Javadoc)
* @see com.Lily.SpringLearning.f_annotation_c_lifecycle.User#add()
*/
@Override
public void add() {
System.out.println("LifeCycle User add() ");
}
@PostConstruct
public void myInit(){
System.out.println("init() !");
}
@PreDestroy
public void myDestory(){
System.out.println("destory() !");
}
}
<?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: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">
<!-- 组件扫描，扫描含有注解的类 -->
<context:component-scan base-package="com.Lily.SpringLearning.f_annotation_c_lifecycle"></context:component-scan>
</beans>
public class Test {
@org.junit.Test
public void test() {
String xmlPath = "com/Lily/SpringLearning/f_annotation_c_lifecycle/beans.xml";
ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
User user = applicationContext.getBean("UserId" ,User.class);
User user2 = applicationContext.getBean("UserId" ,User.class);
System.out.println(user);
System.out.println(user2);
applicationContext.close();
}
}