Spring容器初始化扩展点之ApplicationContextInitializer详解

import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
public class CustomContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        // 在这里编写自定义的初始化逻辑
        System.out.println("CustomContextInitializer is initializing the ApplicationContext...");
        // 示例：设置自定义的环境变量
        applicationContext.getEnvironment().setActiveProfiles("dev");
    }
}

org.springframework.context.ApplicationContextInitializer=com.example.CustomContextInitializer

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication application = new SpringApplication(MyApplication.class);
        application.addInitializers(new CustomContextInitializer());
        application.run(args);
    }
}

@ContextConfiguration(initializers = CustomContextInitializer.class)
public class MyTest {
    // 测试代码
}

public class EnvironmentInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        String env = System.getProperty("env");
        if ("dev".equals(env)) {
            applicationContext.getEnvironment().setActiveProfiles("dev");
        } else if ("prod".equals(env)) {
            applicationContext.getEnvironment().setActiveProfiles("prod");
        }
    }
}

import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.beans.factory.config.BeanDefinition;
public class CustomBeanInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        BeanDefinitionRegistry registry = (BeanDefinitionRegistry) applicationContext.getBeanFactory();
        BeanDefinition beanDefinition = ...; // 创建自定义的 BeanDefinition
        registry.registerBeanDefinition("customBean", beanDefinition);
    }
}