Spring development using annotations

1, the configuration dependent

　　xml scan and automatically detect packet and register the class definitions [used] Bean

<? XML Version = "1.0" encoding = "UTF-. 8" ?> 
< Beans xmlns = "http://www.springframework.org/schema/beans" 
       xmlns: the xsi = "http://www.w3.org / 2001 / XMLSchema-instance " 
       xmlns: context =" http://www.springframework.org/schema/context " 
       xsi: schemaLocation =" http://www.springframework.org/schema/beans 
        HTTPS: // the WWW. springframework.org/schema/beans/spring-beans.xsd 
        http://www.springframework.org/schema/context 
        https://www.springframework.org/schema/context/spring-context.xsd " > 
    <! - - scan base-package and automatically detect and register the class definitions Bean -> 
    <context:component-scan base-package="com.doubleh.pojo"/>
</beans>

　　

2 comment

　　@Component 2.1　　- defined in the class, the bean is registered; equivalent @ Service, @ Controller, @ Repository

　　@Scope 2.2　　- defined scope of the bean, acting on the class

　　@Value 2.3 () 　　- defined on attributes assigned

　　@Autowired 2.4　　- set the properties and methods defined in the class

　　@ComponentScan 2.5　　- scan package, with a configuration using Java beans manner.

　　　　You can be modified and expanded by the application of this behavior custom filter, adding them to includeFiltersor comment excludeFiltersattributes @ComponentScan(or XML configuration element <context:include-filter />or  <context:exclude-filter />sub-element <context:component-scan>). Each filter element needs typeand expressionproperties.

　　　　

Filter Type	Examples of expression	description
Notes (default)	org.example.SomeAnnotation	In the level of the target assembly type on the presence or element present annotations .
Assignable	org.example.SomeClass	It can be assigned to the target component (or extended implementation) class (or interface).
aspect	org.example..*Service+	AspectJ type expressions to match the target component.
Regular Expressions	org\.example\.Default.*	To the class name of the target component matches the regular expression.
custom	org.example.MyTypeFilter	org.springframework.core.type.TypeFilterInterface custom implementation .

　

@Configuration
@ComponentScan(basePackages = "org.example",
        includeFilters = @Filter(type = FilterType.REGEX, pattern = ".*Stub.*Repository"),
        excludeFilters = @Filter(Repository.class))
public class AppConfig {
    ...
}

<beans>
    <context:component-scan base-package="org.example">
        <context:include-filter type="regex"
                expression=".*Stub.*Repository"/>
        <context:exclude-filter type="annotation"
                expression="org.springframework.stereotype.Repository"/>
    </context:component-scan>
</beans>

3, entirely in Java configuration Spring fashion

　　Even Spring xml configuration files are not needed.

　　3.1 class defines a configuration:

// This will be hosted Spring container, registered to container, as is a @Configuration @Component
 // @Configuration represent this class is a configuration equivalent to <Beans> </ Beans> .xml 
@Configuration
 // scan All packets in com.doubleh.pojo 
@ComponentScan ( "com.doubleh.pojo" ) 
// Import @ (other configurations based)
 public  class AppConfig { 

//     equivalent to <the bean> </ the bean>
 //     method name is ID the bean
 //     the return value class is the bean
 //     @Bean
 //     public Cat CAT () {
 //         return new new Cat ();
 //     } 
}

　　　　@ComponentScan("com.doubleh.pojo") 
　　　　　　等价于 beans.xml 的
　　　　<context:component-scan base-package="com.doubleh.pojo"/>　　

　3.2 If a bean:

Use @ComponentScan scan manner must have an annotation on the bean class declaration, the default bean name is the first letter lowercase class name; if @Bean declared in the configuration class, you can not write notes on the class, and is generally not omitted in the configuration class write.

//注册为一个bean
@Component
public class Cat {
    private int id;
    private String name;

    @Value("2")
    public void setId(int id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "Cat{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }

    @Value("李白")
    public void setName(String name) {
        this.name = name;
    }
}　

　3.3 使用AnnotationConfigApplicationContext：

// If used to configure class way to do it, we use AnnotationConfigApplicationContext to get the context 
 ApplicationContext applicationContext = new new AnnotationConfigApplicationContext (appconfig. Class ); 
 Cat getCat = to applicationContext.getBean ( "CAT", Cat. Class ); 
 System.out.println (getCat); 

// through the register to the configuration register class acquire context 
AnnotationConfigApplicationContext CTX = new new AnnotationConfigApplicationContext (); 
ctx.register (AppConfig.class, OtherConfig.class); 
ctx.register (AdditionalConfig.class); 
ctx.refresh (); 

// third @Componentor with JSR-330 -based annotation provided as input to the constructor 
ApplicationContext ctx =new AnnotationConfigApplicationContext(MyServiceImpl.class, Dependency1.class, Dependency2.class); 
MyService myService = ctx.getBean(MyService.class); 
myService.doStuff();

//第四种 用的时候再去扫描
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(); 
ctx.scan("com.acme"); 
ctx.refresh(); 
MyService myService = ctx.getBean(MyService.class);