修改properties文件的目录：在application.yml或者application.properties中配置 spring.message.basename

spring:
  application:
    name: test-worklog
  messages:
    basename: i18n/messages
    encoding: UTF-8

MessageSource的使用：

1. 无参数

operation.success = 操作成功。

String msg1 = this.messageSource.getMessage(" operation.success ", null, Locale.CHINA); 

2. 动态参数

start.ge.end = 开始日期{0}必须小于结束日期{1}！

String [] param = {startDate, endDate};

String msg =getMessage("start.ge.end", param);

@Autowired
private MessageSource messageSource;
/**
 * 国际化
 *
 * @param result
 * @return
 */
public String getMessage(String result, Object[] params) {
  String message = "";
  try {
    Locale locale = LocaleContextHolder.getLocale();
    message = messageSource.getMessage(result, params, locale);
  } catch (Exception e) {
    LOGGER.error("parse message error! ", e);
  }
  return message;
}

补充一个方法，适用于类中无法获取到MessageSource

/**
 * 国际化
 * 注：通过@Autowired private MessageSource messageSource无法获取
 *
 * @param result
 * @return
 */
public String getMessage(String result, Object[] params) {
  ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
  messageSource.setCacheSeconds(-1);
  messageSource.setDefaultEncoding(StandardCharsets.UTF_8.name());
  messageSource.setBasenames("/i18n/messages");

  String message = "";
  try {
    Locale locale = LocaleContextHolder.getLocale();
    message = messageSource.getMessage(result, params, locale);
  } catch (Exception e) {
    log.error("parse message error! ", e);
  }
  return message;
}