- 可以将@Autowired注解为“传统”的setter方法
package com.mypackage;
import org.springframework.beans.factory.annotation.Autowired;
public class SimpleMovieLister {
private MovieFinder movieFinder;
@Autowired
public void setMovieFinder(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
//.....
}
- 可用于构造器或成员变量
package com.mypackage;
import org.springframework.beans.factory.annotation.Autowired;
public class SimpleMovieLister {
@Autowired
private BeanAnnotation beanAnnotation;
private MovieFinder movieFinder;
@Autowired
public void setMovieFinder(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
//.....
}
- 默认情况下，如果因找不到合适的bean将会导致autowiring失败抛出异常，可以通过下面的方式避免
package com.mypackage;
import org.springframework.beans.factory.annotation.Autowired;
public class SimpleMovieLister {
private MovieFinder movieFinder;
@Autowired(required=false)
public void setMovieFinder(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
//.....
}
- 每个类只能有一个构造器被标记为required=true
- @Autowired的必要属性，建议会用@Required注解
例子：
先新建两个接口（InjectionService、InjectionDAO），及实现类
package com.mypackage;
public interface InjectionDAO {
public void save(String args);
}
package com.mypackage; import org.springframework.stereotype.Repository; @Repository
public class InjectionDAOImpl implements InjectionDAO { public void save(String args) {
//模拟数据库操作
System.out.println("DAO保存数据：" + args);
} }
package com.mypackage;
public interface InjectionService {
public void save(String args);
}
package com.mypackage; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service; @Service
public class InjectionServiceImpl implements InjectionService{ @Autowired
private InjectionDAO injectionDAO; public void save(String s){
//模拟业务操作
System.out.println("Service接收参数:"+s);
s=s+":"+this.hashCode();
injectionDAO.save(s);
}
}
XML配置：
<?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-4.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.1.xsd"> <context:component-scan base-package="com.mypackage">
</context:component-scan>
</beans>
单元测试：
package com.mypackage; import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class UnitTest { @Test
public void testAutoWired(){
ApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-beanannotation.xml");
InjectionService service=(InjectionService)context.getBean("injectionServiceImpl");
service.save("this is autowired");; }
}
结果：
2015-7-6 15:52:26 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1342a80d: startup date [Mon Jul 06 15:52:26 CST 2015]; root of context hierarchy
2015-7-6 15:52:26 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [spring-beanannotation.xml]
Service接收参数:this is autowired
DAO保存数据：this is autowired:1811560891
@Autowired也可应用于构造器
修改InjectionServiceImpl实现类（添加setter）
package com.mypackage; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service; @Service
public class InjectionServiceImpl implements InjectionService{ private InjectionDAO injectionDAO; @Autowired
public void setInjectionDAO(InjectionDAO injectionDAO) {
this.injectionDAO = injectionDAO;
} public void save(String s){
//模拟业务操作
System.out.println("Service接收参数:"+s);
s=s+":"+this.hashCode();
injectionDAO.save(s);
}
}
测试结果：
2015-7-6 15:55:23 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@939b78e: startup date [Mon Jul 06 15:55:23 CST 2015]; root of context hierarchy
2015-7-6 15:55:23 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [spring-beanannotation.xml]
Service接收参数:this is autowired
DAO保存数据：this is autowired:1860295362