最近在研究Spring Boot 的Validator以及国际化，在墙里墙外找了很多很久，可能是因为版本的更新迭代，找到的资料基本都用不了了。自己折腾了半天，终于琢磨出来了，特此记录。觉得过程啰嗦的可以直奔demo代码
本文代码地址：https://github.com/choimroc/SpringBoot_i18nDemo
本文实验的软件环境如下：
Spring Boot 2.1.8.RELEASEJDK 1.8IDEA 2019.2.3Gradle 5.6.2Validator的具体用法不是本文的重点，网上也已经有大量的相关文章，所以就不展开说了。这里要提一下的是hibernate-validator包下的注解，在5.0版本之后就已经标记过时（@deprecated）了，hibernate-validator也是建议使用javax.validation 包下的注解来替换，用法都差不多。
在很多文章中都出现过下面的这两种配置（来自hibernate-validator官方文档）
import org.hibernate.validator.HibernateValidator; import org.hibernate.validator.cfg.ConstraintMapping; import javax.validation.Validation; import javax.validation.Validator; import javax.validation.ValidatorFactory; //这样 ValidatorFactory validatorFactory = Validation.byProvider(HibernateValidator.class) .configure() .failFast(true) .addMapping((ConstraintMapping) null) .buildValidatorFactory(); Validator validator = validatorFactory.getValidator(); //或者这样 ValidatorFactory validatorFactory = Validation.byProvider(HibernateValidator.class) .configure() .addProperty("hibernate.validator.fail_fast", "true") .buildValidatorFactory(); Validator validator = validatorFactory.getValidator();这里说一下failFast的作用，在Validator进行校验时，会校验所有的参数，然后把错误一起返回，如下：
{ "timestamp": 1570029617189, "status": 500, "error": "Internal Server Error", "message": "test.param1: 参数1不能为空, test.param2: 参数2不能为空", "path": "/test" }而设置了failFast之后，如果校验时发现了错误就会停止后续参数的校验。
我们可以看到上面的配置使用的javax.validation包下的Validator，但是在我所使用的Spring Boot版本中，实际使用的是org.springframework.validation包下的Validator，具体可以查看源码里org.springframework.web.servlet.config.annotation.WebMvcConfigurer这个接口的代码。所以上面所用的配置已经不适用了（PS：具体是什么时候替换的我也不清楚，了解情况的同学可以在留言区告知一声，感谢~）。
查看了org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration，发现defaultValidator用的是org.springframework.validation.beanvalidation.LocalValidatorFactoryBean，但是LocalValidatorFactoryBean下并没有configure和failFast。难道新版本之后就没办法设置了？对比了LocalValidatorFactoryBean和javax.validation后发现LocalValidatorFactoryBean有一个很可疑的属性validationPropertyMap，于是有了下面的配置
@Configuration @EnableWebMvc public class WebConfiguration implements WebMvcConfigurer { @Bean public LocalValidatorFactoryBean mvcValidator() { LocalValidatorFactoryBean localValidatorFactoryBean = new LocalValidatorFactoryBean(); localValidatorFactoryBean.getValidationPropertyMap().put("hibernate.validator.fail_fast", "true"); return localValidatorFactoryBean; } }运行之后，发起请求，发现真的起作用了，nice！
注意，如果直接运行会抛出异常信息Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true，还需要在application.yml或者application.properties中加入如下配置
# yml spring: main: allow-bean-definition-overriding: true # properties spring.main.allow-bean-definition-overriding=true上面的返回格式是Spring Boot自带的，而且HttpStatus是500，如果我们想要返回自定义的格式，就得做全局异常捕获。废话不多说，直接上代码：
@RestControllerAdvice public class GlobalExceptionHandler { @ResponseStatus(HttpStatus.OK) @ExceptionHandler(BindException.class) public Result bindExceptionHandler(final BindException e) { String message = e.getBindingResult().getAllErrors().stream().map(DefaultMessageSourceResolvable::getDefaultMessage).collect(Collectors.joining()); return new Result(500, message); } @ResponseStatus(HttpStatus.OK) @ExceptionHandler(MethodArgumentNotValidException.class) public Result handler(final MethodArgumentNotValidException e) { String message = e.getBindingResult().getAllErrors().stream().map(DefaultMessageSourceResolvable::getDefaultMessage).collect(Collectors.joining()); return new Result(500, message); } @ResponseStatus(HttpStatus.OK) @ExceptionHandler(ConstraintViolationException.class) public Result handler(final ConstraintViolationException e) { String message = e.getConstraintViolations().stream().map(ConstraintViolation::getMessage).collect(Collectors.joining()); return new Result(500, message); } }返回的数据如下：
{ "code": 500, "msg": "参数1不能为空" }直奔主题，常规的配置如下：
@Configuration @EnableWebMvc public class WebConfiguration implements WebMvcConfigurer { public WebConfiguration() { } /*国际化 start*/ @Bean public LocaleChangeInterceptor localeChangeInterceptor() { LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor(); //自定义参数 localeChangeInterceptor.setParamName("language"); return localeChangeInterceptor; } @Bean public LocaleResolver localeResolver() { SessionLocaleResolver localeResolver = new SessionLocaleResolver(); //指定默认语言为中文 localeResolver.setDefaultLocale(Locale.SIMPLIFIED_CHINESE); return localeResolver; } @Bean public LocalValidatorFactoryBean mvcValidator() { LocalValidatorFactoryBean localValidatorFactoryBean = new LocalValidatorFactoryBean(); localValidatorFactoryBean.getValidationPropertyMap().put("hibernate.validator.fail_fast", "true"); //为Validator配置国际化 localValidatorFactoryBean.setValidationMessageSource(resourceBundleMessageSource()); return localValidatorFactoryBean; } @Bean(name = "messageSource") public ResourceBundleMessageSource resourceBundleMessageSource() { ResourceBundleMessageSource resourceBundleMessageSource = new ResourceBundleMessageSource(); //指定国际化的Resource Bundle地址 resourceBundleMessageSource.setBasename("i18n/messages"); //指定国际化的默认编码 resourceBundleMessageSource.setDefaultEncoding("UTF-8"); return resourceBundleMessageSource; } @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(localeChangeInterceptor()); } /*国际化 end*/ }这样就能完成国际化了，是不是 so easy？！但是这样写有一个问题，就是language参数必须是url参数，如http://localhost:8080/test?language=en_US，一般对于这种公共的参数，我们都希望放在Headers中的，那有没有办法呢？ 我们首先来查看一下org.springframework.web.servlet.i18n.LocaleChangeInterceptor这个类的源码，这里面有一个关键的方法preHandle：
//这里只贴出关键代码，有兴趣的可以自己去研究 public class LocaleChangeInterceptor extends HandlerInterceptorAdapter { …… @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException { //正是这一行代码，导致只能通过url参数传递language String newLocale = request.getParameter(getParamName()); if (newLocale != null) { if (checkHttpMethod(request.getMethod())) { LocaleResolver localeResolver = RequestContextUtils.getLocaleResolver(request); if (localeResolver == null) { throw new IllegalStateException( "No LocaleResolver found: not in a DispatcherServlet request?"); } try { localeResolver.setLocale(request, response, parseLocaleValue(newLocale)); } catch (IllegalArgumentException ex) { if (isIgnoreInvalidLocale()) { if (logger.isDebugEnabled()) { logger.debug("Ignoring invalid locale value [" + newLocale + "]: " + ex.getMessage()); } } else { throw ex; } } } } // Proceed in any case. return true; } …… }既然找到了源头那就好办了，我们只需要继承源码中的这个类，依然画葫芦，重写关键方法就行了；在源码中，有个checkHttpMethod方法是用private标识的，所以我们同样要复制一份:
public class LocaleInterceptor extends LocaleChangeInterceptor { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException { //getParameter 改为 getHeader String newLocale = request.getHeader(getParamName()); if (newLocale != null) { if (checkHttpMethod(request.getMethod())) { LocaleResolver localeResolver = RequestContextUtils.getLocaleResolver(request); if (localeResolver == null) { throw new IllegalStateException( "No LocaleResolver found: not in a DispatcherServlet request?"); } try { localeResolver.setLocale(request, response, parseLocaleValue(newLocale)); } catch (IllegalArgumentException ex) { if (isIgnoreInvalidLocale()) { if (logger.isDebugEnabled()) { logger.debug("Ignoring invalid locale value [" + newLocale + "]: " + ex.getMessage()); } } else { throw ex; } } } } // Proceed in any case. return true; } //复制自源码中 private boolean checkHttpMethod(String currentMethod) { String[] configuredMethods = getHttpMethods(); if (ObjectUtils.isEmpty(configuredMethods)) { return true; } for (String configuredMethod : configuredMethods) { if (configuredMethod.equalsIgnoreCase(currentMethod)) { return true; } } return false; } } //修改WebConfiguration @Configuration @EnableWebMvc public class WebConfiguration implements WebMvcConfigurer { @Bean public LocaleChangeInterceptor localeChangeInterceptor() { //改为我们自定义的LocaleInterceptor LocaleChangeInterceptor localeChangeInterceptor = new LocaleInterceptor(); //指定参数 localeChangeInterceptor.setParamName("language"); return localeChangeInterceptor; } }这才是真正的so easy！同学们，这说明什么问题呀？这说明只要能够充分利用源码，我们就可以只做出些许修改就能达到目的，可谓是四两拨千斤呀！
然后我们再封装一个获取国际化资源的工具类：
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.MessageSource; import org.springframework.context.i18n.LocaleContextHolder; import org.springframework.stereotype.Component; import java.util.Locale; @Component public class LocaleMessage { private final MessageSource messageSource; @Autowired public LocaleMessage(MessageSource messageSource) { this.messageSource = messageSource; } public String getMessage(String code) { return getMessage(code, new Object[]{}); } public String getMessage(String code, String defaultMessage) { return getMessage(code, new Object[]{}, defaultMessage); } public String getMessage(String code, String defaultMessage, Locale locale) { return getMessage(code, new Object[]{}, defaultMessage, locale); } public String getMessage(String code, Locale locale) { return getMessage(code, new Object[]{}, "", locale); } public String getMessage(String code, Object[] args) { return getMessage(code, args, ""); } public String getMessage(String code, Object[] args, Locale locale) { return getMessage(code, args, "", locale); } public String getMessage(String code, Object[] args, String defaultMessage) { Locale locale = LocaleContextHolder.getLocale(); return getMessage(code, args, defaultMessage, locale); } public String getMessage(String code, Object[] args, String defaultMessage, Locale locale) { return messageSource.getMessage(code, args, defaultMessage, locale); } }使用：
1.在src\main\resources下新建文件夹i18n，在i18n新建Resource Bundle,命名为messages 2.添加中文和英文 3.添加一些数据 4.在Controller中使用
@Validated @RestController @RequestMapping("test") public class TestController { private final LocaleMessage localeMessage; @Autowired public TestController(LocaleMessage localeMessage) { this.localeMessage = localeMessage; } @PostMapping public Result test( @NotBlank(message = "{test.msg1}") String param1, @NotBlank(message = "{test.msg2}") String param2 ) { return new Result(200, localeMessage.getMessage("test.msg3")); } }记录，分享，交流。
