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1) @ConditionalOnBean

  功能：在IOC容器中存在指定bean时，加载当前bean

//将Teacher作为bean注入IOC
@Component
public class Teacher{    
}public class Student{
}@Configuration
public class MyBeanFactory{//如果IOC容器中存在Teacher这个bean,则将student作为bean注入@ConditionalOnBean(value={Teacher.class})@BeanStudent student(){return new Student();}
}

2) @ConditionalOnMissingBean

   功能：在IOC中不包含指定bean时，加载当前bean

public class Student{
}@Configuration
public class MyBeanFactory{//如果IOC容器中不存在Student,则注入Student@ConditionalOnMissingBean(value={Student.class})@BeanStudent student(){return new Student();}
}

3) @ConditionalOnClass

   功能：如果当前项目包含指定类，则加载当前bean

// com.entity.Student
public class Student{
}@Configuration
public class MyBeanFactory{//如果项目中含有Student类，则加载当前bean@ConditionalOnClass(name="com.entity.student")@BeanStudent student(){return Student();}
}

4) @ConditionalOnMissingClass

功能：如果当前项目不包含指定类，则加载当前bean

public class Student{
}@Configuration
public class MyBeanFactory{//如果项目中不包含Teacher类，则加载当前bean@ConditionalOnMissingClass(name="com.entity.Teacher")@BeanStudent student(){return Student();}
}

5) @ConditionalOnProperty

功能：如果配置文件有指定属性，并且属性值与预期值一致，则注入当前bean

在配置文件配置如下属性:
*****************************
student.enable=true     
*****************************    @Configuration
public class MyBeanFactory{//如果配置文件中配置了student.enable，并且student.enable=true， 则加载当前bean@ConditionalOnProperty(value="student.enable" , havingValue="true" )@BeanStudent student(){return Student();}
}

6) @ConditionalOnResource

功能：如果项目中包含指定资源，则加载当前bean

// 假设有 /static/index.html
@Configuration
public class MyBeanFactory{//如果包含 /static/index.html 资源，就加载当前bean@ConditionalOnResource(resources="/static/index.html" )@BeanStudent student(){return Student();}
}

7) @ConditionalOnWebApplication 、@ConditionalOnNotWebApplication

功能：如果当前项目是web应用 ( 或不是web应用 ) 时生成当前bean

@Configuration
public class MyBeanFactory{/**    如果是web应用，则加载Student作为bean*                否则加载Teacher作为bean*/@ConditionalOnWenApplication@BeanStudent student(){return Student();}@ConditionalOnNotWebApplication@BeanTeacher teacher(){return new Teacher();}
}