Springboot项目启动时加载数据库数据到内存

@Component
public class CodeCache {
  public static Map<String, String> codeMap = new HashMap<String, String>();
  @Autowired
  private ICodeService codeService;
  @PostConstruct
  public void init(){
    System.out.println("系统启动中。。。加载codeMap");
    List<Code> codeList = codeService.selectAll();
    for (Code code : codeList) {
      codeMap.put(code.getKey(), code.getValue());
    }
  }
  @PreDestroy
    public void destroy(){
        System.out.println("系统运行结束");
    }
}

System.out.println(CodeCache.codeMap.get("name"));