应用启动数据初始化接口CommandLineRunner和Application详解

/**
 * Run the Spring application, creating and refreshing a new
 * {@link ApplicationContext}.
 * @param args the application arguments (usually passed from a Java main method)
 * @return a running {@link ApplicationContext}
 */
public ConfigurableApplicationContext run(String... args) {
	StopWatch stopWatch = new StopWatch();
	stopWatch.start();
	ConfigurableApplicationContext context = null;
	Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
	configureHeadlessProperty();
	SpringApplicationRunListeners listeners = getRunListeners(args);
	listeners.starting();
	try {
		ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
		ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
		configureIgnoreBeanInfo(environment);
		Banner printedBanner = printBanner(environment);
		context = createApplicationContext();
		exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
				new Class[] { ConfigurableApplicationContext.class }, context);
		prepareContext(context, environment, listeners, applicationArguments, printedBanner);
		refreshContext(context);
		afterRefresh(context, applicationArguments);
		stopWatch.stop();
		if (this.logStartupInfo) {
			new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
		}
		listeners.started(context);
		//调用Runner，执行初始化操作
		callRunners(context, applicationArguments);
	}
	catch (Throwable ex) {
		handleRunFailure(context, ex, exceptionReporters, listeners);
		throw new IllegalStateException(ex);
	}
	try {
		listeners.running(context);
	}
	catch (Throwable ex) {
		handleRunFailure(context, ex, exceptionReporters, null);
		throw new IllegalStateException(ex);
	}
	return context;
}

@Order(1)
@Component
public class CommandLineRunnerInit implements CommandLineRunner {
    private Logger logger = LoggerFactory.getLogger(this.getClass());
    private final String LOG_PREFIX = ">>>>>>>>>>CommandLineRunner >>>>>>>>>> ";
    @Override
    public void run(String... args) throws Exception {
        try {
            this.logger.error("{} args:{}", LOG_PREFIX, StringUtils.join(args, ","));
        } catch (Exception e) {
            logger.error("CommandLineRunnerInit run failed", e);
        }
    }
}

@Order(2)
@Component
public class ApplicationRunnerInit implements ApplicationRunner {
    private Logger logger = LoggerFactory.getLogger(this.getClass());
    private final String LOG_PREFIX = ">>>>>>>>>>ApplicationRunner >>>>>>>>>> ";
    private final UserRepository userRepository;
    public ApplicationRunnerInit(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
    @Override
    public void run(ApplicationArguments args) throws Exception {
        try {
            this.logger.error("{} args:{}", LOG_PREFIX, JSONObject.toJSONString(args));
            for (String optionName : args.getOptionNames()) {
                this.logger.error("{} argName:{} argValue:{}", LOG_PREFIX, optionName, args.getOptionValues(optionName));
            }
            this.logger.error("{} user count:{}", LOG_PREFIX, this.userRepository.count());
        } catch (Exception e) {
            logger.error("CommandLineRunnerInit run failed", e);
        }
    }
}

private void callRunners(ApplicationContext context, ApplicationArguments args) {
 List<Object> runners = new ArrayList<>();
 //先添加的ApplicationRunner实现
 runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
 //再添加的CommandLineRunner实现
 runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
 //如果设置了顺序，则按设定顺序重新排序
 AnnotationAwareOrderComparator.sort(runners);
 for (Object runner : new LinkedHashSet<>(runners)) {
  if (runner instanceof ApplicationRunner) {
   callRunner((ApplicationRunner) runner, args);
  }
  if (runner instanceof CommandLineRunner) {
   callRunner((CommandLineRunner) runner, args);
  }
 }
}

@Component
@Order(value = 10)
public class AgentApplicationRun2 implements ApplicationRunner {
 @Override
 public void run(ApplicationArguments applicationArguments) throws Exception {
 }
}

@Component
@Order(value = 11)
public class AgentApplicationRun implements CommandLineRunner {
 @Override
 public void run(String... strings) throws Exception {
 }
}