一、问题
在平时的业务模块开发过程中，难免会需要做一些全局的任务、缓存、线程等等的初始化工作，那么如何解决这个问题呢？方法有多种，但具体又要怎么选择呢？
二、资源初始化
1.既然要做资源的初始化，那么就需要了解一下springboot启动过程（这里大体说下启动过程,详细：https://www.cnblogs.com/dennyzhangdd/p/8028950.html）
按照前面的分析，Spring-boot容器启动流程总体可划分为2部分：
执行注解：扫描指定范围下的bean、载入自动配置类对应的bean加载到IOC容器。
man方法中具体SpringAppliocation.run()，全流程贯穿SpringApplicationEvent(经典的spring事件驱动模型),有6个子类：
- ApplicationFailedEvent.class
- ApplicationPreparedEvent.class
- ApplicationReadyEvent.class
- ApplicationStartedEvent.class
- ApplicationStartingEvent.class
- SpringApplicationEvent.class
2、CommandLineRunner和ApplicationRunner
@Component
@Order(1)
public class MyCommandLineRunner implements CommandLineRunner {
@Override
public void run(String... args) throws Exception {
System.out.println("...init resources by implements CommandLineRunner");
}
}
@Component
@Order(2)
public class MyApplicationRunner implements ApplicationRunner {
@Override
public void run(ApplicationArguments applicationArguments) throws Exception {
System.out.println("...init resources by implements ApplicationRunner");
}
}
3、@PostConstruct
＠Component
public Class AAA {
@Autowired
private BBB b;
public AAA() {
System.out.println("此时b还未被注入: b = " + b);
}
@PostConstruct
private void init() {
System.out.println("此时b已经被注入: b = " + b);
}
}
4、InitializingBean
public class InitSequenceBean implements InitializingBean {
public InitSequenceBean() {
System.out.println("InitSequenceBean: constructor");
}
@PostConstruct
public void postConstruct() {
System.out.println("InitSequenceBean: postConstruct");
}
public void initMethod() {
System.out.println("InitSequenceBean: init-method");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("InitSequenceBean: afterPropertiesSet");
}
}
5、ApplicationListener
@Component
public class DataSourceInitListener implements ApplicationListener<ContextRefreshedEvent> {//ContextRefreshedEvent为启动事件
private static final Logger LOGGER = LoggerFactory.getLogger(DataSourceInitListener.class);
@Autowired
private SystemConfigService systemConfigService;
@Autowired
private ItemService itemService;
@Autowired
private SystemResultService systemResultService;
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
if(event.getApplicationContext().getParent() == null) {//判断是否执行过，执行过则不再执行
LOGGER.info("初始化systemConfig数据");
systemConfigService.initConfig();
LOGGER.info("初始化返回消息数据");
systemResultService.initResult();
LOGGER.info("系统初始化结束...........");
}
}
}
