SpringBoot 启动源码解析系列一：构造器实例化

SpringBoot 启动类示例：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}

通过 SpringApplication 静态方法 run 执行启动：

public static ConfigurableApplicationContext run(Object source, String... args) {
    return run(new Object[]{source}, args);
}

public static ConfigurableApplicationContext run(Object[] sources, String[] args) {
    return (new SpringApplication(sources)).run(args);
}

调用构造函数：

public SpringApplication(Object... sources) {
    this.bannerMode = Mode.CONSOLE;
    this.logStartupInfo = true;
    this.addCommandLineProperties = true;
    this.headless = true;
    this.registerShutdownHook = true;
    this.additionalProfiles = new HashSet();
    this.initialize(sources);
}

核心方法 initalize ：

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();
}

首先：把 DemoApplication 类对象设置到 SpringApplication 持有的 sources 属性中，是个 Set 集合
其次：判断是否是 Web 程序环境
第三：设置初始化器
第四：设置事件监听器
第五：找出程序入口

赏

谢谢你请我吃糖果