Spring Boot 2.0深度实践之核心技术篇(二)

spring自动装配

1. 激活自动装配：@EnableAutoConfiguration
2. 实现自动装配：@XXXConfiguration
3. 配置自动装配实现：META-INF/spring.factories

理解 SpringApplication

• SpringApplication的运行
  
  • SpringApplication.run
  • SpringApplicationBuilder.run
• 配置spring bean源

public class SpirngBootApplication {

    public static void main(String[] args) {

        Set<String> stringSet = new HashSet<>();
        stringSet.add(SpringConfig.class.getName());
        SpringApplication springApplication = new SpringApplication();
        springApplication.setSources(stringSet);

        ConfigurableApplicationContext context = springApplication.run(args);
        System.out.println(context.getBean(SpringConfig.class));
    }

    @SpringBootApplication
    public static class SpringConfig {

    }
}

• 推断web应用类型

public enum WebApplicationType {

    /**
     * The application should not run as a web application and should not start an
     * embedded web server.
     */
    NONE,

    /**
     * The application should run as a servlet-based web application and should start an
     * embedded servlet web server.
     */
    SERVLET,

    /**
     * The application should run as a reactive web application and should start an
     * embedded reactive web server.
     */
    REACTIVE

}

通过线程堆栈来推断引导类

    private Class<?> deduceMainApplicationClass() {
        try {
            StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
            for (StackTraceElement stackTraceElement : stackTrace) {
                if ("main".equals(stackTraceElement.getMethodName())) {
                    return Class.forName(stackTraceElement.getClassName());
                }
            }
        }