Spring注解开发@Bean和@ComponentScan使用案例

组件注册

用@Bean来注册

搭建好maven web工程

pom加入spring-context,spring-core等核心依赖

创建实例类com.hjj.bean.Person, 生成getter,setter方法

public class Person {

private String name;

private int age;

}

创建com.hjj.config.MainConfig

@Configuration //告诉spring是一个配置类

public class MainConfig {

// 给容器中注册一个Bean,类行为返回值的类型,id默认是用方法名作为id

@Bean("mikePerson")

public Person person(){

return new Person("mike",20);

}

}

主测试类

public class MainTest {

public static void main(String[] args) {

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);

Person bean = applicationContext.getBean(Person.class);

System.out.println(bean);

String[] beanNamesForType = applicationContext.getBeanNamesForType(Person.class);

for (String type : beanNamesForType) {

System.out.println(type); //配置类中的方法名,注意:通过修改配置类的@bean value也可以修改

}

}

}

@ComponentScan包扫描

配置类中MainConfig.java

@Configuration //告诉spring是一个配置类

@ComponentScan("com.hjj") // 扫描包的路径

public class MainConfig {

// 给容器中注册一个Bean,类行为返回值的类型,id默认是用方法名作为id

@Bean("mikePerson")

public Person person(){

return new Person("mike",20);

}

}

新建测试的com.hjj.controller,service,dao

@Controller

public class BookController {

}

@Repository

public class BookDao {

}

@Service

public class BookService {

}

单元测试

@Test

public void test01(){

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);

String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames(); //获取所有组件

for (String beanDefinitionName : beanDefinitionNames) {

System.out.println(beanDefinitionName);

}

}

ComponentScan字段,有includeFilter(),和excludeFilter() 只包含或排除某些组件

@ComponentScan(value = "com.hjj",excludeFilters={@Filter(type=FilterType.ANNOTATION,classes={Controller.class,Service.class})})

@ComponentScan(value = "com.hjj",includeFilters={@Filter(type=FilterType.ANNOTATION,classes={Controller.class,Service.class})},userDefaultFilters=false)

// excludeFilter源码

ComponentScan.Filter[] excludeFilters() default {};

// ComponentScan.Filter源码

@Retention(RetentionPolicy.RUNTIME)

@Target({})

public @interface Filter {

FilterType type() default FilterType.ANNOTATION;

@AliasFor("classes")

Class<?>[] value() default {};

@AliasFor("value")

Class<?>[] classes() default {};

String[] pattern() default {};

}

@ComponentScan被@Repeatable(ComponentScans.class),可以重复写,用来写不同的执行策略。

@ComponentScans 里面可以放ComponentScan类型的值

@Retention(RetentionPolicy.RUNTIME)

@Target({ElementType.TYPE})

@Documented

public @interface ComponentScans {

ComponentScan[] value();

}

FilterType

public enum FilterType {

ANNOTATION, // 按注解扫描

ASSIGNABLE_TYPE, // 按给定的类型

ASPECTJ, // 可以用aspectJ表达式

REGEX, // 正则表达式

CUSTOM; // 自定义规则

private FilterType() {

}

}

ASSIGNABLE_TYPE

@ComponentScan(value = "com.hjj",

includeFilters ={@ComponentScan.Filter(type=FilterType.ASSIGNABLE_TYPE,classes = {BookService.class})})

// config配置如上注解后 bookservice,可以被发现

@Test

public void demoTest1(){

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);

String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();

for (String beanDefinitionName : beanDefinitionNames) {

System.out.println(beanDefinitionName);

}

}

Custom 可以自定义配置或写业务扫描类的信息,match返回true则是加到组件

1.复写TypeFilter的match方法

public class MyTypeFilter implements TypeFilter {

/**

*

* @param metadataReader 读取到的当前正在扫描的类的信息

* @param metadataReaderFactory 可以获取到其他任何类信息

* @return

* @throws IOException

*/

@Override

public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException {

// 获取当前类注解的信息

AnnotationMetadata annotationMetadata = metadataReader.getAnnotationMetadata();

// 获取当前正在扫描类的信息

ClassMetadata classMetadata = metadataReader.getClassMetadata();

// 获取当前类资源(类的路径等)

Resource resource = metadataReader.getResource();

String className = classMetadata.getClassName();

System.out.println("className:" + className);

return false;

}

}

2. 加上注解

@Configuration //告诉spring是一个配置类

@ComponentScan(value = "com.hjj",

includeFilters ={

@ComponentScan.Filter(type=FilterType.CUSTOM,classes = {MyTypeFilter.class})},

useDefaultFilter=false)

public class MainConfig {

}

@Test

public void test01(){

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);

String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();

for (String beanDefinitionName : beanDefinitionNames) {

System.out.println(beanDefinitionName);

}

}

结果

className:com.hjj.test.IOCTest

className:com.hjj.MainTest

className:com.hjj.bean.Person

className:com.hjj.config.MyTypeFilter

className:com.hjj.demo.DemoTest

className:com.hjj.demo.Employee

className:com.hjj.demo.Manager

org.springframework.context.annotation.internalConfigurationAnnotationProcessor

org.springframework.context.annotation.internalAutowiredAnnotationProcessor

org.springframework.context.annotation.internalCommonAnnotationProcessor

org.springframework.context.event.internalEventListenerProcessor

org.springframework.context.event.internalEventListenerFactory

mainConfig

以上是 Spring注解开发@Bean和@ComponentScan使用案例 的全部内容, 来源链接: utcz.com/z/358940.html

回到顶部