Spring：IoC 用法（六、自动扫描Bean用法）

发现 Bean 扩展

1、定义Bean

定义Controller 控制层

@Controller
public class TestController {

// 测试方法
public String testController() {
return "SUCCESS";
}
}

定义Service服务层接口

public interface TestService {
// 测试注入：调用方法
String testService();
}

定义Service服务层接口实现

// 接口实现类
@Service
public class TestServiceImpl implements TestService {

@Autowired
private TestRepository repository;

// 测试方法
public String testService() {
return repository.testRepository();
}
}

定义Repository数据层接口

public interface TestRepository {
// 测试注入：调用方法
String testRepository();
}

定义Repository数据层接口实现

// 接口实现类
@Repository
public class TestRepositoryImpl implements TestRepository {
// 测试注入方法
public String testRepository() {
return "------------------------- >>> 获取数据成功!!";
}
}

2、发现Bean

1）、XML 发现 Bean

扫描指定包路径及以下所有子路径，带有@Component注解及子注解的类，可以同时存在多个

<context:component-scan base-package="test.define"/>

use-default-filters 属性：自动配置时，细粒度初始化Bean加载

true：默认为true

<context:component-scan base-package="test.define" use-default-filters="true">
<!-- 指定路径下，排除带有@Service -->
<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service"/>
</context:component-scan>

false：如果不想发现指定路径所有带注解的类，而是想发现指定的类，或者排除指定的类

<context:component-scan base-package="test.define" use-default-filters="false">
<!-- 指定路径下，仅扫描带有@Controller的类 -->
<context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>

2）、Java 发现 Bean

默认扫描当前包及子包，带有@Component注解及子注解的类

@Configuration
@ComponentScan
public class TestConfig {

}

扫描单个指定路径下的包及子包，带有@Component注解及子注解的类

@Configuration
@ComponentScan("test.define")
public class TestConfig {

}

@Configuration
@ComponentScan(basePackages = "test.define")
public class TestConfig {

}

扫描多个指定路径下的包及子包，带有@Component注解及子注解的类

@Configuration
@ComponentScan(basePackages = {"test.define","test.define"})
public class TestConfig {

}

发现一个带有@Component注解及子注解的指定类

@Configuration
@ComponentScan(basePackageClasses = TestController.class)
public class TestConfig {

}

发现多个带有@Component注解及子注解的指定类

@Configuration
@ComponentScan(basePackageClasses = {TestController.class, TestServiceImpl.class, TestRepositoryImpl.class})
public class TestConfig {

}

use-default-filters 属性：自动配置时，细粒度初始化Bean加载

true（默认为true）

排除带有@Service的注解

@Configuration
@ComponentScan(useDefaultFilters = true, excludeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION, value = Service.class)})
public class TestConfig {

}

false

仅扫描带有@Controller的注解

@Configuration
@ComponentScan(useDefaultFilters = false, includeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION, value = Controller.class)})
public class TestConfig {

}

3、测试代码

依赖

<properties>
<spring.version>4.2.1.RELEASE</spring.version>
</properties>

<dependencies>
<!-- Spring 依赖注入 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- 仅测试 -->
<dependency>
<groupId>
7db9
junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>

测试类

public class Test {

@org.junit.Test
public void testXMLConfig() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring/spring.xml");

TestController controller = context.getBean(TestController.class);
String data1 = controller.testController();
System.out.println("Controller 结果：" + data1);

TestService service = context.getBean(TestServiceImpl.class);
String data2 = service.testService();
System.out.println("Service 结果：" + data2);

context.close();
}

@org.junit.Test
public void testJavaConfig() {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(TestConfig.class);

TestController controller = context.getBean(TestController.class);
String data = controller.testController();
System.out.println("结果：" + data);

TestService service = context.getBean(TestServiceImpl.class);
String data2 = service.testService();
System.out.println("Service 结果：" + data2);

context.close();
}
}