SpringBoot 启动源码解析系列三：实例化 ApplicationContextInitializer

2018-01-02

SpringApplication initialize 方法：

private void initialize(Object[] sources) {
    if (sources != null && sources.length > 0) {
        this.sources.addAll(Arrays.asList(sources));
    }

    this.webEnvironment = this.deduceWebEnvironment();
    this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
    this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
    this.mainApplicationClass = this.deduceMainApplicationClass();
}

setInitializers 方法即找到 ApplicationContextInitializer 类并实例化

ApplicationContextInitializer 是 Spring 框架中的接口，其作用可以理解为在 ApplicationContext 执行 refresh 之前，调用 initialize() 方法，对 ApplicationContext 做进一步的设置和处理：

1
2
3

public interface ApplicationContextInitializer<C extends ConfigurableApplicationContext> {
    void initialize(C var1);
}

ApplicationContextInitializer 在 SpringBoot 中包含两块：

spring-boot-x.x.x.RELEASE.jar/META-INF/spring.factories中：

# Application Context Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\
org.springframework.boot.context.ContextIdApplicationContextInitializer,\
org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\
org.springframework.boot.context.embedded.ServerPortInfoApplicationContextInitializer

spring-boot-autoconfigure-x.x.x.RELEASE.jar/META-INF/spring.factories中：

# Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
org.springframework.boot.autoconfigure.logging.AutoConfigurationReportLoggingInitializer