springBean了解
1. 定义springBean
2. Beandefinition 元信息
3. 命名spring bean
4. spring bean的别名
5. 注册spring Beandefinition
注册BeanDefinition 方式
1. xml
<beans>
<description>ggBall的bean工厂</description>
<import resource="textBean.xml"/>
<alias name="veryComplexDomain" alias="vcd"/>
<bean id="user" class="com.zhu.entity.User" >
<constructor-arg index="0">
<ref bean="son"/>
</constructor-arg>
</bean>
<bean id="son" class="com.zhu.entity.Son">
<property name="id" value="1"/>
<property name="name" value="小名"/>
</bean>
</beans>
2. 注解 （@Bean,@Component,@Import）
@Configuration
@Import(User.class)
public class Config {
@Bean
public User user(){
return new User();
}
@Bean
public Son son() {
return new Son();
}
}
3. java Api
- BeanDefinitionRegistry#registerBeanDefinition
/**
* 命名方式 注册BeanDefinition
* registry.registerBeanDefinition(beanName,beanDefinition);
* @param registry
* @param beanName
* @param classBean
*/
public static void registerBeanDefinition(BeanDefinitionRegistry registry,String beanName,Class classBean) {
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(classBean);
definitionBuilder.addPropertyValue("name","xxx")
.addPropertyValue("id","1");
AbstractBeanDefinition beanDefinition = definitionBuilder.getBeanDefinition();
registry.registerBeanDefinition(beanName,beanDefinition);
}
- BeanDefinitionReaderUtils#registerWithGeneratedName
/**
* 非命名方式 注册BeanDefinition
* BeanDefinitionReaderUtils.registerWithGeneratedName(beanDefinition,registry);
* @param registry
* @param classBean
*/
public static void registerBeanDefinition(BeanDefinitionRegistry registry,Class classBean) {
BeanDefinitionBuilder definitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(classBean);
definitionBuilder.addPropertyValue("name","xxx_1")
.addPropertyValue("id","1");
AbstractBeanDefinition beanDefinition = definitionBuilder.getBeanDefinition();
BeanDefinitionReaderUtils.registerWithGeneratedName(beanDefinition,registry);
}
6. 实例化spring bean
我个人理解bean的元信息是Bean初始化时所需要的配置参数。
通过构造器
xml配置元信息
<bean id="user" class="com.zhu.entity.User" >
<!--这是有参构造器-->
<constructor-arg index="0">
<ref bean="son"/>
</constructor-arg>
</bean>
java类配置元信息
未找到
注解配置元信息
// spring实际上扫描类的构造方法，实例化bean
@Component
public class Son {
private Long id;
private String name;
}
通过静态工厂方法
xml配置
@Data
public class StaticFactoryUser {
private Long id;
private String name;
public static StaticFactoryUser createInstance() {
return new StaticFactoryUser();
}
}
<!-- 静态工厂实例化bean -->
<bean id="staticFactoryUser" class="com.zhu.instantiate_bean.StaticFactoryUser" factory-method="createInstance"></bean>
java Api配置
- 未找到
通过实例化工厂方法
xml配置
public interface UserFactory {
default StaticFactoryUser createUser() {
return StaticFactoryUser.createInstance();
}
public class InsUserFactory implements UserFactory {
}
}
<!--实例化工厂方法实例化bean-->
<bean id="insUserFactory" class="com.zhu.instantiate_bean.factory.InsUserFactory"></bean>
<bean id="noneStaticFactoryUser" factory-bean="insUserFactory" factory-method="createUser"></bean>
java Api配置
- 未找到
通过factoryBean实例化bean
public class UserFactoryBean implements FactoryBean {
@Override
public Object getObject() throws Exception {
return new User();
}
@Override
public Class<?> getObjectType() {
return User.class;
}
}
<!-- 利用factoryBean实例化bean-->
<bean id="userFactoryBean" class="com.zhu.instantiate_bean.factory_bean.UserFactoryBean"></bean>
通过serviceLoader实例化bean
- resource目录下建立META-INF/services目录,再创建文件，文件名使用接口名，里面的内容填写接口实现类的全限定名
- 大概流程：serviceLoader 会去找
META-INF/services下文件，找到实现类的全限定名，再利用class.forName(“全限定名”)得到calss类，再实例化对象。
/**
* 利用serviceLoader 实例化bean
*/
public static void testServiceLoader() {
ServiceLoader<UserFactory> serviceLoader = ServiceLoader.load(UserFactory.class);
Iterator<UserFactory> iterator = serviceLoader.iterator();
while (iterator.hasNext()) {
UserFactory userFactory = iterator.next();
User user = userFactory.createUser();
System.out.println("use ServiceLoader user = " + user);
}
}
通过serviceLoaderBeanFactory 实例化bean
- resource目录下建立META-INF/services目录,再创建文件，文件名使用接口名，里面的内容填写接口实现类的全限定名
- xml配置
<!-- 利用serviceLoaderBeanFactory 创建 serviceLoader ,再利用serviceLoader 实例化bean-->
<bean id="userServiceLoaderFactoryBean" class="org.springframework.beans.factory.serviceloader.ServiceLoaderFactoryBean">
<property name="serviceType" value="com.zhu.instantiate_bean.factory.UserFactory"></property>
</bean>
- 从容器拿到serviceLoader,后面流程和
通过serviceLoader实例化bean一样的
/**
* 利用serviceLoaderBeanFactory 创建 serviceLoader ,再利用serviceLoader 实例化bean
*/
public static void testServiceFactoryBean() {
ServiceLoader<UserFactory> serviceLoader = (ServiceLoader<UserFactory>)applicationContext.getBean("userServiceLoaderFactoryBean");
Iterator<UserFactory> iterator = serviceLoader.iterator();
while (iterator.hasNext()) {
UserFactory userFactory = iterator.next();
User user = userFactory.createUser();
System.out.println("use ServiceFactoryBean user = " + user);
}
}
通过 AutowireCapableBeanFactory 实例化bean
/**
* 通过 AutowireCapableBeanFactory 实例化bean
*/
public static void testAutowireCapableBeanFactory() {
// applicationContext 虽然继承beanFactory 但是想通过applicationContext拿到beanFactory只能get
AutowireCapableBeanFactory autowireCapableBeanFactory = applicationContext.getAutowireCapableBeanFactory();
InsUserFactory userFactory = autowireCapableBeanFactory.createBean(InsUserFactory.class);
User user = userFactory.createUser();
System.out.println("use autowireCapableBeanFactory user = " + user);
}