透過 Spring 自帶的 ImportBeanDefinitionRegistrar 介面來實現這個功能。
分別為以下幾個步驟：
創建 Bean#
import java.io.Serializable;
public class User implements Serializable {
private String username;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
自定義 MyImportBeanDefinitionRegistrar 實現 ImportBeanDefinitionRegistrar 介面#
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;
public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
RootBeanDefinition beanDefinition = new RootBeanDefinition(User.class);
beanDefinition.getPropertyValues().add("username", "我是創建Bean時存儲進來的");
registry.registerBeanDefinition("cn.gaofangye.springbeanstudy.ImportBeanDefinitionRegistrar.demo1.User", beanDefinition);
}
}
這段代碼是給 Bean 中的 username 屬性設置值，需要給屬性增加 set 方法才可以。
自定義 MyConfig 配置類 Import 自定義創建 Bean 的類#
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
@Configuration
@Import(MyImportBeanDefinitionRegistrar.class)
public class MyConfig {
}
只有這樣，才能成功將自定義的 Bean 注入到 Spring IOC 容器中。
編寫測試類驗證#
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
User user = applicationContext.getBean(User.class);
System.out.println(user.getUsername());
}
}
輸出結果#
11:27:56.094 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@5e91993f
11:27:56.103 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
11:27:56.165 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
11:27:56.165 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
11:27:56.166 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
11:27:56.167 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
11:27:56.170 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'myConfig'
11:27:56.173 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'cn.gaofangye.springbeanstudy.ImportBeanDefinitionRegistrar.demo1.User'
我是創建Bean時存儲進來的
自定義 BeanName 通過 BeanName 獲取 IOC 中的 Bean#
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;
public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
RootBeanDefinition beanDefinition = new RootBeanDefinition(User.class);
beanDefinition.getPropertyValues().add("username", "我是創建Bean時存儲進來的");
registry.registerBeanDefinition("user", beanDefinition);
}
}
registry.registerBeanDefinition("user", beanDefinition);
通過 registerBeanDefinition 的第一個參數，給 Bean 設置 BeanName。
驗證通過 BeanName 獲取 IOC 中的 Bean#
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MyConfig.class);
User user = applicationContext.getBean(User.class);
System.out.println(user.getUsername());
User findUserByBeanName = (User) applicationContext.getBean("user");
System.out.println("通過 BeanName 獲取到的 Bean: " + findUserByBeanName.getUsername());
}
}
輸出結果#
12:30:24.491 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@5e91993f
12:30:24.500 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
12:30:24.560 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
12:30:24.560 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
12:30:24.561 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
12:30:24.562 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
12:30:24.565 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'myConfig'
12:30:24.567 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'user'
我是創建Bean時存儲進來的
通過 BeanName 獲取到的 Bean: 我是創建Bean時存儲進來的