【学习笔记】Logback及Appender相关生命周期_reinitializeloggingsystem-优快云博客

在做项目时，发现自定义的logback的Appender的start方法执行的时机非常的靠前，在Spring框架注入bean之前就完成了。

问了一下公司的架构师，start方法的执行时机有两类情况，第一种是服务启动的时候，也就是刚刚提到的时机。

第二种是服务触发了logback的刷新机制，找到了spring-cloud-commons项目下的源码，如下：

private void reinitializeLoggingSystem(ConfigurableEnvironment environment,
        String oldLogConfig, LogFile oldLogFile) {
    Map<String, Object> props = Binder.get(environment)
            .bind("logging", Bindable.mapOf(String.class, Object.class)).orElseGet(Collections::emptyMap);
    if (!props.isEmpty()) {
        String logConfig = environment.resolvePlaceholders("${logging.config:}");
        LogFile logFile = LogFile.get(environment);
        LoggingSystem system = LoggingSystem
                .get(LoggingSystem.class.getClassLoader());
        try {
            ResourceUtils.getURL(logConfig).openStream().close();
            // Three step initialization that accounts for the clean up of the logging
            // context before initialization. Spring Boot doesn't initialize a logging
            // system that hasn't had this sequence applied (since 1.4.1).
            system.cleanUp();
            system.beforeInitialize();
            system.initialize(new LoggingInitializationContext(environment),
                    logConfig, logFile);
        }
        catch (Exception ex) {
            PropertySourceBootstrapConfiguration.logger
                    .warn("Logging config file location '" + logConfig
                            + "' cannot be opened and will be ignored");
        }
    }
}

Environment由Spring的环境配置注入，是Profile和PropertyResolver的组合。

执行上述方法即可完成logback的刷新，调用start方法。