Spring注解驱动开发(一)-----组件注册
注册bean
xml方式
1、beans.xml-----很简单,里面注册了一个person bean
<?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"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd"> <bean id="person" class="com.atguigu.bean.Person">
<property name="age" value="18"></property>
<property name="name" value="zhangsan"></property>
</bean>
</beans>
2、person
package com.atguigu.bean; import org.springframework.beans.factory.annotation.Value; public class Person {
private String name;
private Integer age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
} public Person(String name, Integer age) {
super();
this.name = name;
this.age = age;
}
public Person() {
super();
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + ", nickName=" + nickName + "]";
}
}
3、MainTest-----测试类
package com.atguigu; import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import com.atguigu.bean.Person;
import com.atguigu.config.MainConfig; public class MainTest { @SuppressWarnings("resource")
public static void main(String[] args) {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
Person bean = (Person) applicationContext.getBean("person");
System.out.println(bean);
}
测试结果:
注解方式
1、MainConfig-----配置类
@Configuration //告诉Spring这是一个配置类
//给容器中注册一个Bean;类型为返回值的类型,id默认是用方法名作为id
@Bean("person")
public Person person01(){
return new Person("lisi", 20);
}
}
2、MainTest
package com.atguigu; import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import com.atguigu.bean.Person;
import com.atguigu.config.MainConfig; public class MainTest { @SuppressWarnings("resource")
public static void main(String[] args) {
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
Person bean = applicationContext.getBean(Person.class);
System.out.println(bean); String[] namesForType = applicationContext.getBeanNamesForType(Person.class);
for (String name : namesForType) {
System.out.println(name);
}
}
}
3、@Configuration-----可以看出是继承了@Component
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Configuration {
@AliasFor(annotation = Component.class)
String value() default ""; }
自动扫描
xml方式
1、beans.xml
<?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"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
<context:component-scan base-package="com.atguigu"></context:component-scan>
<bean id="person" class="com.atguigu.bean.Person">
<property name="age" value="18"></property>
<property name="name" value="zhangsan"></property>
</bean>
</beans>
注解方式
1、MainConfig
package com.atguigu.config; import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.ComponentScans; import com.atguigu.bean.Person; //配置类==配置文件
@Configuration //告诉Spring这是一个配置类
@ComponentScan(value="com.atguigu") //value:指定要扫描的包
public class MainConfig {
//给容器中注册一个Bean;类型为返回值的类型,id默认是用方法名作为id
@Bean("person")
public Person person01(){
return new Person("lisi", 20);
} }
2、BookController
package com.atguigu.controller; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller; import com.atguigu.service.BookService; @Controller
public class BookController { @Autowired
private BookService bookService; }
3、BookService
package com.atguigu.service; import javax.annotation.Resource;
import javax.inject.Inject; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service; import com.atguigu.dao.BookDao; @Service
public class BookService { @Autowired(required=false)
private BookDao bookDao; public void print(){
System.out.println(bookDao);
} @Override
public String toString() {
return "BookService [bookDao=" + bookDao + "]";
}
}
4、BookDao
package com.atguigu.dao; import org.springframework.stereotype.Repository; //名字默认是类名首字母小写
@Repository
public class BookDao { private String lable = "1"; public String getLable() {
return lable;
} public void setLable(String lable) {
this.lable = lable;
} @Override
public String toString() {
return "BookDao [lable=" + lable + "]";
}
}
5、IocTest
package com.atguigu.test; import java.util.Map; import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment; import com.atguigu.bean.Blue;
import com.atguigu.bean.Person;
import com.atguigu.config.MainConfig;
import com.atguigu.config.MainConfig2; public class IOCTest { @SuppressWarnings("resource")
@Test
public void test01(){
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
String[] definitionNames = applicationContext.getBeanDefinitionNames();
for (String name : definitionNames) {
System.out.println(name);
}
}
}
@ComponentScan
1、excludeFilters
@ComponentScan(value="com.atguigu",excludeFilters = {
@Filter(type=FilterType.ANNOTATION,classes={Controller.class,Service.class}))
排除controller以及service,不允许注册。
注:这里需要注意一个问题,需要使用excludeFilters的时候,use-default-filters需要设置为true或者不设置,因为use-default-filters属性的默认值为true。否则会出现报错的现象,例如无法成功注册相应的bean。原因如下:
要分析这个错误,就要先了解 use-default-filters 这个属性的作用。use-default-filters 属性的默认值为 true,即使用默认的 Filter 进行包扫描,而默认的 Filter 对标有 @Service,@Controller和@Repository 的注解的类进行扫描而我们只希望 SpringMVC 的配置扫描 @Controllerce 注解标注的类,不希望它扫描其余注解标注的类,所以设置了 use-default-filters 为 false,并使用 context:include-filter 子标签设置其只扫描带有 @Controller 注解标注的类。
而 Spring 就不同了,我们希望 Spring 只不扫描带有 @Controller 注解标注的类,而扫描其他注解标注的类,而这时建立在使用默认的 Filter 进行扫描的基础上,设置了 context:exclude-filter 标签,不扫描 @Controller 注解标注的类,所以不应该设置 use-default-filters 为 false,所以这就解释了为什么一开始启动 Tomcat 时报了一个找不到 Service 的错误。
2、includeFilters
@ComponentScan(value="com.atguigu",includeFilters = {
@Filter(type=FilterType.ANNOTATION,classes={Controller.class}),useDefaultFilters=false)
只扫描controller。-----需要添加useDefaultFilters=false
@ComponentScans
@ComponentScans(
value = {
@ComponentScan(value="com.atguigu",includeFilters = {
@Filter(type=FilterType.ANNOTATION,classes={Controller.class})
},useDefaultFilters = false)
}
)
其实就是可以定义多个扫描策略。
TypeFilter
- @ComponentScan value:指定要扫描的包
- excludeFilters = Filter[] :指定扫描的时候按照什么规则排除那些组件
- includeFilters = Filter[] :指定扫描的时候只需要包含哪些组件
- FilterType.ANNOTATION:按照注解
- FilterType.ASSIGNABLE_TYPE:按照给定的类型;
- FilterType.ASPECTJ:使用ASPECTJ表达式
- FilterType.REGEX:使用正则指定
- FilterType.CUSTOM:使用自定义规则
其中注解最为常见。
设置组件作用域
@Scope
spring中默认都是单例bean,不过也可以通过@Scope进行设置。
1、MainConfig2
package com.atguigu.config; import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope; import com.atguigu.bean.Blue;
import com.atguigu.bean.Color;
import com.atguigu.bean.ColorFactoryBean;
import com.atguigu.bean.Person;
import com.atguigu.bean.Red;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar;
import com.atguigu.condition.MyImportSelector;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest; @Configuration
public class MainConfig2 { //默认是单实例的
/**
* ConfigurableBeanFactory#SCOPE_PROTOTYPE
* @see ConfigurableBeanFactory#SCOPE_SINGLETON
* @see org.springframework.web.context.WebApplicationContext#SCOPE_REQUEST request
* @see org.springframework.web.context.WebApplicationContext#SCOPE_SESSION sesssion
* @return\
* @Scope:调整作用域
* prototype:多实例的:ioc容器启动并不会去调用方法创建对象放在容器中。
* 每次获取的时候才会调用方法创建对象;
* singleton:单实例的(默认值):ioc容器启动会调用方法创建对象放到ioc容器中。
* 以后每次获取就是直接从容器(map.get())中拿,
* request:同一次请求创建一个实例
* session:同一个session创建一个实例
*/
@Scope("prototype")
@Bean("person")
public Person person(){
System.out.println("给容器中添加Person....");
return new Person("张三", 25);
}
}
2、IocTest
package com.atguigu.test; import java.util.Map; import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment; import com.atguigu.bean.Blue;
import com.atguigu.bean.Person;
import com.atguigu.config.MainConfig;
import com.atguigu.config.MainConfig2; public class IOCTest { @Test
public void test02(){
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig2.class); System.out.println("ioc容器创建完成....");
Object bean = applicationContext.getBean("person");
Object bean2 = applicationContext.getBean("person");
System.out.println(bean == bean2);
}
}
3、测试结果
@Lazy-----只针对于singleton模式
package com.atguigu.config; import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope; import com.atguigu.bean.Blue;
import com.atguigu.bean.Color;
import com.atguigu.bean.ColorFactoryBean;
import com.atguigu.bean.Person;
import com.atguigu.bean.Red;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar;
import com.atguigu.condition.MyImportSelector;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest; @Configuration
public class MainConfig2 { //默认是单实例的
/**
* 懒加载:
* 单实例bean:默认在容器启动的时候创建对象;
* 懒加载:容器启动不创建对象。第一次使用(获取)Bean创建对象,并初始化;
*
*/
@Scope("singleton")
@Lazy
@Bean("person")
public Person person(){
System.out.println("给容器中添加Person....");
return new Person("张三", 25);
}
}
@Conditional-----按照一定的条件进行判断,满足条件给容器中注册bean
配置在方法上
示例:根据是windows还是linux系统,判断person为Bill还是Linus
1、MainConfig
package com.atguigu.config; import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope; import com.atguigu.bean.Blue;
import com.atguigu.bean.Color;
import com.atguigu.bean.ColorFactoryBean;
import com.atguigu.bean.Person;
import com.atguigu.bean.Red;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar;
import com.atguigu.condition.MyImportSelector;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest; @Configuration
public class MainConfig2 { /**
* @Conditional({Condition}) : 按照一定的条件进行判断,满足条件给容器中注册bean
*
* 如果系统是windows,给容器中注册("bill")
* 如果是linux系统,给容器中注册("linus")
*/
@Conditional({WindowsCondition.class})
@Bean("bill")
public Person person01(){
return new Person("Bill Gates",62);
} @Conditional(LinuxCondition.class)
@Bean("linus")
public Person person02(){
return new Person("linus", 48);
}
}
2、LinuxCondition
package com.atguigu.condition; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotatedTypeMetadata; //判断是否linux系统
public class LinuxCondition implements Condition { /**
* ConditionContext:判断条件能使用的上下文(环境)
* AnnotatedTypeMetadata:注释信息
*/
@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
// TODO是否linux系统
//1、能获取到ioc使用的beanfactory
ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
//2、获取类加载器
ClassLoader classLoader = context.getClassLoader();
//3、获取当前环境信息
Environment environment = context.getEnvironment();
//4、获取到bean定义的注册类
BeanDefinitionRegistry registry = context.getRegistry(); String property = environment.getProperty("os.name"); //可以判断容器中的bean注册情况,也可以给容器中注册bean
boolean definition = registry.containsBeanDefinition("person");
if(property.contains("linux")){
return true;
} return false;
} }
3、WindowsCondition
package com.atguigu.condition; import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotatedTypeMetadata; //判断是否windows系统
public class WindowsCondition implements Condition { @Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
Environment environment = context.getEnvironment();
String property = environment.getProperty("os.name");
if(property.contains("Windows")){
return true;
}
return false;
} }
4、IOCTest
package com.atguigu.test; import java.util.Map; import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment; import com.atguigu.bean.Blue;
import com.atguigu.bean.Person;
import com.atguigu.config.MainConfig;
import com.atguigu.config.MainConfig2; public class IOCTest {
@Test
public void test03(){
String[] namesForType = applicationContext.getBeanNamesForType(Person.class);
ConfigurableEnvironment environment = applicationContext.getEnvironment();
//动态获取环境变量的值;Windows 10
String property = environment.getProperty("os.name");
System.out.println(property);
for (String name : namesForType) {
System.out.println(name);
} Map<String, Person> persons = applicationContext.getBeansOfType(Person.class);
System.out.println(persons); }
}
运行结果:
由于当前系统是win10,所以只有Bill对象存在。
那么如何试验得到Linus呢?
通过run configuration的-Dos.name,直接更改jvm参数,然后eviroment中取os.name就为linux了。
配置在类上
MainConfig
package com.atguigu.config; import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope; import com.atguigu.bean.Blue;
import com.atguigu.bean.Color;
import com.atguigu.bean.ColorFactoryBean;
import com.atguigu.bean.Person;
import com.atguigu.bean.Red;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar;
import com.atguigu.condition.MyImportSelector;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest; //类中组件统一设置。满足当前条件,这个类中配置的所有bean注册才能生效;
@Conditional({WindowsCondition.class})
@Configuration
public class MainConfig2 { /**
* @Conditional({Condition}) : 按照一定的条件进行判断,满足条件给容器中注册bean
*
* 如果系统是windows,给容器中注册("bill")
* 如果是linux系统,给容器中注册("linus")
*/ @Bean("bill")
public Person person01(){
return new Person("Bill Gates",62);
} @Conditional(LinuxCondition.class)
@Bean("linus")
public Person person02(){
return new Person("linus", 48);
}
}
给容器快速导入一个组件
给容器注册组件的方式
1、包扫描+组件标注注解(@Controller/@Service/@Repository/@Component)[自己写的类]
2、@Bean[导入的第三方包里面的组件]
3、@Import[快速给容器中导入一个组件]
- a、@Import(要导入到容器中的组件);容器中就会自动注册这个组件,id默认是全类名
- b、ImportSelector:返回需要导入的组件的全类名数组;
- c、ImportBeanDefinitionRegistrar:手动注册bean到容器中
4、使用Spring提供的 FactoryBean(工厂Bean);
- a、默认获取到的是工厂bean调用getObject创建的对象
- b、要获取工厂Bean本身,我们需要给id前面加一个 && colorFactoryBean
@Import
@Configuration
//@Import导入组件,id默认是组件的全类名
@Import({Color.class,Red.class})
public class MainConfig2 { }
ImportSelector-----实现这个接口(将需要导入的组件放入数组中)
1、MyImportSelector
package com.atguigu.condition; import org.springframework.context.annotation.ImportSelector;
import org.springframework.core.type.AnnotationMetadata; //自定义逻辑返回需要导入的组件
public class MyImportSelector implements ImportSelector { //返回值,就是到导入到容器中的组件全类名
//AnnotationMetadata:当前标注@Import注解的类的所有注解信息
@Override
public String[] selectImports(AnnotationMetadata importingClassMetadata) {
// TODO Auto-generated method stub
//importingClassMetadata
//方法不要返回null值
return new String[]{"com.atguigu.bean.Blue","com.atguigu.bean.Yellow"};
} }
2、MainConfig
package com.atguigu.config; import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope; import com.atguigu.bean.Blue;
import com.atguigu.bean.Color;
import com.atguigu.bean.ColorFactoryBean;
import com.atguigu.bean.Person;
import com.atguigu.bean.Red;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar;
import com.atguigu.condition.MyImportSelector;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest; @Configuration
@Import({MyImportSelector.class})
public class MainConfig2 { }
ImportBeanDefinitionRegistrar-----实现这个接口(创建BeanDefinition,通过BeanDefinitionRegistry.registerBeanDefinition()导入)
1、MyImportBeanDefinitionRegistrar
package com.atguigu.condition; import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.type.AnnotationMetadata; import com.atguigu.bean.RainBow; public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar { /**
* AnnotationMetadata:当前类的注解信息
* BeanDefinitionRegistry:BeanDefinition注册类;
* 把所有需要添加到容器中的bean;调用
* BeanDefinitionRegistry.registerBeanDefinition手工注册进来
*/
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { boolean definition = registry.containsBeanDefinition("com.atguigu.bean.Red");
boolean definition2 = registry.containsBeanDefinition("com.atguigu.bean.Blue");
if(definition && definition2){
//指定Bean定义信息;(Bean的类型,Bean。。。)
RootBeanDefinition beanDefinition = new RootBeanDefinition(RainBow.class);
//注册一个Bean,指定bean名
registry.registerBeanDefinition("rainBow", beanDefinition);
}
} }
2、MainConfig2
package com.atguigu.config; import org.springframework.context.annotation.Configuration;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar; @Configuration
@Import({MyImportBeanDefinitionRegistrar.class})
//@Import导入组件,id默认是组件的全类名
public class MainConfig2 { }
FactoryBean-----实现spring提供的这个工厂bean
1、ColorFactoryBean
package com.atguigu.bean; import org.springframework.beans.factory.FactoryBean; //创建一个Spring定义的FactoryBean
public class ColorFactoryBean implements FactoryBean<Color> { //返回一个Color对象,这个对象会添加到容器中
@Override
public Color getObject() throws Exception {
// TODO Auto-generated method stub
System.out.println("ColorFactoryBean...getObject...");
return new Color();
} @Override
public Class<?> getObjectType() {
// TODO Auto-generated method stub
return Color.class;
} //是单例?
//true:这个bean是单实例,在容器中保存一份
//false:多实例,每次获取都会创建一个新的bean;
@Override
public boolean isSingleton() {
// TODO Auto-generated method stub
return false;
} }
2、MainConfig2
package com.atguigu.config; import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Scope; import com.atguigu.bean.Blue;
import com.atguigu.bean.Color;
import com.atguigu.bean.ColorFactoryBean;
import com.atguigu.bean.Person;
import com.atguigu.bean.Red;
import com.atguigu.condition.LinuxCondition;
import com.atguigu.condition.MyImportBeanDefinitionRegistrar;
import com.atguigu.condition.MyImportSelector;
import com.atguigu.condition.WindowsCondition;
import com.atguigu.test.IOCTest; @Configuration
public class MainConfig2 {
/**
* 给容器中注册组件;
* 1)、包扫描+组件标注注解(@Controller/@Service/@Repository/@Component)[自己写的类]
* 2)、@Bean[导入的第三方包里面的组件]
* 3)、@Import[快速给容器中导入一个组件]
* 1)、@Import(要导入到容器中的组件);容器中就会自动注册这个组件,id默认是全类名
* 2)、ImportSelector:返回需要导入的组件的全类名数组;
* 3)、ImportBeanDefinitionRegistrar:手动注册bean到容器中
* 4)、使用Spring提供的 FactoryBean(工厂Bean);
* 1)、默认获取到的是工厂bean调用getObject创建的对象
* 2)、要获取工厂Bean本身,我们需要给id前面加一个&
* &colorFactoryBean
*/
@Bean
public ColorFactoryBean colorFactoryBean(){
return new ColorFactoryBean();
}
}
注:虽然@Bean的是ColorFactoryBean,但是其实是将此工厂内的bean注册到容器中。如果要获取工厂bean本身,getBean("&..."),在名称前加“&”。
其实也就是说:
AnnotationConfigApplicationContext app = new AnnotationConfigApplicationContext(Cap6MainConfig.class);
//获取的是Color对象
Object bean1 = app.getBean("colorFactoryBean");
//获取的是ColorFactoryBean工厂对象
Object bean3 = app.getBean("&colorFactoryBean");
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