spring除了XML的配置,还可以用Annotation注解来实现spring的配置功能,下面来介绍里面一些配置方法
1.Annotation第一步
a)修改xml文件,参考文档<context:annotation-config/>基于注解(Annotation-based)的配置
在 Spring 2.5中已经可以用注解的方式去驱动 Spring 的依赖注射了。更重要的是,@Autowired注解提供了与第 3.3.5 节 “自动装配(autowire)协作者”一节中描述的同样功能,并且提供了更细致的控制与更好的适应性。Spring 2.5 也支持 JSR-250 中的一些注解,例如@Resource,@PostConstruct,以及@PreDestroy。
<?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-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> </beans>
(加载了<context:annotation-config/>就相当于隐式注册 post-processors, 包括了 AutowiredAnnotationBeanPostProcessor,CommonAnnotationBeanPostProcessor,PersistenceAnnotationBeanPostProcessor,也包括了前面提到的RequiredAnnotationBeanPostProcessor四个bean,用来完成注解的加载)
加了:xmlns:context="http://www.springframework.org/schema/context"
与<context:annotation-config/>
xsd定义了它所控制的xml都能写什么,就是我们当前文件的命名空间(装着我能写的名字)
2.Autowired
a)默认按类型by type
例子:
<?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-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> <bean id="u" class="cn.edu.hpu.dao.Impl.UserDaoImpl"> <property name="daoId" value="1"></property> </bean> <bean id="userService" class="cn.edu.hpu.service.UserService"> </bean> </beans>
注意,此时userService的bean里面并没有加id=u的bean。我们用注解来进行AutoWired
在UserService的getUserDao方法上面加注解@Autowired(默认byType)
package cn.edu.hpu.service; import org.springframework.beans.factory.annotation.Autowired; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.dao.Impl.UserDaoImpl; import cn.edu.hpu.model.User; public class UserService { private UserDao userDao; public void init(){ System.out.println("init"); } public UserDao getUserDao() { return userDao; } @Autowired public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void add(User u){ this.userDao.save(u); } public void destroy(){ System.out.println("destroy"); } }
测试:
package cn.edu.hpu.service; import org.junit.Test; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception{ ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml"); UserService userService=(UserService)ctx.getBean("userService"); System.out.println(userService.getUserDao()); ctx.destroy(); } }
UserDaoImpl.java:改写了toString方法,返回daoId
package cn.edu.hpu.dao.Impl; import java.util.List; import java.util.Map; import java.util.Set; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserDaoImpl implements UserDao{ private int daoId; public int getDaoId() { return daoId; } public void setDaoId(int daoId) { this.daoId = daoId; } public void save(User u) { System.out.println("add success!!"); } @Override public String toString() { return "daoid="+daoId; } }
测试结果:
daoid=1
也就是用Annotation也可以实现Autowired
b)如果想用byName,使用@Qulifier
如果有好几个Type一样的,就应该用byName了:
<?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-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> <bean id="u" class="cn.edu.hpu.dao.Impl.UserDaoImpl"> <property name="daoId" value="1"></property> </bean> <bean id="u2" class="cn.edu.hpu.dao.Impl.UserDaoImpl"> <property name="daoId" value="2"></property> </bean> <bean id="userService" class="cn.edu.hpu.service.UserService"> </bean> </beans>
在UserService的getUserDao方法的参数前加@Qualifier("XX"),其中
"XX"是相应bean的id
UserService.java:
package cn.edu.hpu.service; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.dao.Impl.UserDaoImpl; import cn.edu.hpu.model.User; public class UserService { private UserDao userDao; public void init(){ System.out.println("init"); } public UserDao getUserDao() { return userDao; } @Autowired public void setUserDao(@Qualifier("u2")UserDao userDao) { this.userDao = userDao; } public void add(User u){ this.userDao.save(u); } public void destroy(){ System.out.println("destroy"); } }
测试:
package cn.edu.hpu.service; import org.junit.Test; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception{ ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml"); UserService userService=(UserService)ctx.getBean("userService"); System.out.println(userService.getUserDao()); ctx.destroy(); } }结果:
daoid=2
说明注解@Qualifier("u2")起到了作用
c)写在private filed(第三种输入形式)(不建议,破坏封装)
@Autowired(required=false)就是可以去自动获取,如果没有也可以不要(可有可无)
d)如果写在set上,@qualifier需要写在参数上
补充:
前面在XML中提到的ini-method和的destroy-method用注解实现就是在相应方法上加:
@PostConstruct与@PreDestroy
@Scope("XXX")里面指定是用什么样的生命范围(singleton、prototype)
尊重开源精神,尊重劳动成果,转载请注明出处:http://blog.csdn.net/acmman/article/details/43889483