让Spring Controller 的方法基本数据类型参数支持Bean Validation

让Spring Controller 的方法基本数据类型参数支持Bean Validation

Spring中的Bean Validation

我们知道Spring MVC层是默认可以支持Bean Validation的，尝试使用了一下感觉很不方便，只支持对Bean的验证，还需要在Bean后面加一个BindingResult作为参数。而在我们的工程中有很多接口都是基本数据类型作为参数的。下面分享怎么来实现MVC层对基本数据类型提供Bean Validation的支持。

Spring Mvc 层默认的Bean Validation支持配置可以参考这位朋友的博文：http://jinnianshilongnian.iteye.com/blog/1990081

Spring中对Bean Validation可以支持方法级别的验证的，这块只支持Service层的，可以参考http://jinnianshilongnian.iteye.com/blog/1495594 。我们的实现中的很多代码也是参考了Spring这块的实现。

MVC层Bean Validation的扩展

我们通过mvc的拦截器配合注解来实现这样的一个扩展。我们拦截Controller方法上带有@Valid注解的方法(这个注解来自Bean Validation规范)，然后通过Spring的RequestMappingHandlerAdapter来获取每一个参数的值，然后使用org.hibernate.validator.internal.engine.ValidatorImpl （Hibernate对Bean Validation规范的实现，它额外提供了对方法参数的验证，原本的规范中的api是没有的）来根据每个参数上面的验证注解来验证这些参数是否合法。验证失败的话抛出ConstraintViolationException。

这样的一个验证过程，下面是这个拦截器的代码：

/**
* 添加Spring Controller 方法级别的Bean Validation的支持
* @author JiangFeng
*
*/
public class ValidationInterceptor implements HandlerInterceptor{
protected final Log logger = LogFactory.getLog(getClass());

private List<HandlerMethodArgumentResolver> argumentResolvers;
@Autowired
private Validator validator;
@Autowired
private RequestMappingHandlerAdapter adapter;

private final Map<MethodParameter, HandlerMethodArgumentResolver> argumentResolverCache =
new ConcurrentHashMap<MethodParameter, HandlerMethodArgumentResolver>(256);
private final Map<Class<?>, Set<Method>> initBinderCache = new ConcurrentHashMap<Class<?>, Set<Method>>(64);

@Autowired
public ValidationInterceptor(RequestMappingHandlerAdapter requestMappingHandlerAdapter){
argumentResolvers = requestMappingHandlerAdapter.getArgumentResolvers();
}

@Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object handler) throws Exception {

LocalValidatorFactoryBean validatorFactoryBean = (LocalValidatorFactoryBean)validator;
ValidatorImpl validatorImpl = (ValidatorImpl) validatorFactoryBean.getValidator();
ServletWebRequest webRequest = new ServletWebRequest(request, response);
HandlerMethod method = (HandlerMethod)handler;
Valid valid = method.getMethodAnnotation(Valid.class);
if(valid!=null){
Class<?>[] groups = new Class<?>[0];
MethodParameter[] parameters = method.getMethodParameters();
Object[] parameterValues = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
HandlerMethodArgumentResolver resolver = getArgumentResolver(parameter);
Assert.notNull(resolver, "Unknown parameter type [" + parameter.getParameterType().getName() + "]");
ModelAndViewContainer mavContainer = new ModelAndViewContainer();
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
WebDataBinderFactory webDataBinderFactory = getDataBinderFactory(method);
Object value = resolver.resolveArgument(parameter, mavContainer, webRequest, webDataBinderFactory);
parameterValues[i] = value;
}
Set<ConstraintViolation<Object>> violations = validatorImpl.validateParameters(method.getBean(), method.getMethod(), parameterValues, groups);
if (!violations.isEmpty()) {
throw new ConstraintViolationException(violations);
}
}
return true;
}

private WebDataBinderFactory getDataBinderFactory(HandlerMethod handlerMethod) throws Exception {
Class<?> handlerType = handlerMethod.getBeanType();
Set<Method> methods = this.initBinderCache.get(handlerType);
if (methods == null) {
methods = HandlerMethodSelector.selectMethods(handlerType, RequestMappingHandlerAdapter.INIT_BINDER_METHODS);
this.initBinderCache.put(handlerType, methods);
}
List<InvocableHandlerMethod> initBinderMethods = new ArrayList<InvocableHandlerMethod>();
for (Method method : methods) {
Object bean = handlerMethod.getBean();
initBinderMethods.add(new InvocableHandlerMethod(bean, method));
}
return new ServletRequestDataBinderFactory(initBinderMethods, adapter.getWebBindingInitializer());
}

private HandlerMethodArgumentResolver getArgumentResolver(
MethodParameter parameter) {
HandlerMethodArgumentResolver result = this.argumentResolverCache.get(parameter);
if (result == null) {
for (HandlerMethodArgumentResolver methodArgumentResolver : this.argumentResolvers) {
if (logger.isTraceEnabled()) {
logger.trace("Testing if argument resolver [" + methodArgumentResolver + "] supports [" +
parameter.getGenericParameterType() + "]");
}
if (methodArgumentResolver.supportsParameter(parameter)) {
result = methodArgumentResolver;
this.argumentResolverCache.put(parameter, result);
break;
}
}
}
return result;
}

@Override
public void postHandle(HttpServletRequest request,
HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {

}

@Override
public void afterCompletion(HttpServletRequest request,
HttpServletResponse response, Object handler, Exception ex)
throws Exception {

}

}

我们还需要在spring mvc的配置文件中启用Bean Validation

<bean id="validator"
class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean">
<property name="providerClass" value="org.hibernate.validator.HibernateValidator" />
<!-- 如果不加默认到 使用classpath下的 ValidationMessages.properties -->
<property name="validationMessageSource" ref="messageSource" />
</bean>

<!-- 国际化的消息资源文件（本系统中主要用于显示/错误消息定制） -->
<bean id="messageSource"
class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="useCodeAsDefaultMessage" value="false" />
<property name="defaultEncoding" value="UTF-8" />
<property name="cacheSeconds" value="60" />
</bean>

具体应用

Bean Validation配合上统一异常处理，然后再加上前端js里面对json的统一解析。整个开发过程中已经不需要对验证做任何处理了。

我的框架中的应用场景的代码

@RequestMapping("/handle/addFacilityAdd.action")
@ResponseBody
@Valid
@Workflow
public Result addFacilityAdd(
@NotEmpty(message = "设备类型不能为空") @RequestParam(value = "facilityId", required = false) String facilityId,
@Digits(fraction = 6, integer = 3) @RequestParam(value = "longitude", required = false) Double longitude,
@Digits(fraction = 6, integer = 3) @RequestParam(value = "latitude", required = false) Double latitude,
@NotEmpty(message = "地址不能为空") @RequestParam(value = "address", required = false) String address,
@NotEmpty(message = "内容不能为空") @RequestParam(value = "content", required = false) String content)
throws Exception

演示失败返回

{"success":false,"returnTime":"2014-04-18 10:51:50","error":{"errorCode":1002,"errorMessage":"错误的参数","fieldErrors":[{"field":"content","message":"内容不能为空"},{"field":"address","message":"地址不能为空"},{"field":"facilityId","message":"设备类型不能为空"}]},"result":{}}

统一异常拦截后的前端验证js方法

var Valid = {};
Valid.valid = function (d) {
if(typeof d !='object'){
d = eval('(' + d + ')');
}
if (!d.success) {
if(d.error.fieldErrors.length>0){
for (var error in d.error.fieldErrors) {
Alert.warning(d.error.fieldErrors[error].message);
}
}else{
Alert.warning(d.error.errorMessage);
}

try {
console.error(d);
} catch (e) {

}
return false;
} else {
return true;
}
}

在ajax的回调方法中先调用一验证，就可以直接提示出Bean Validation验证失败的错误信息了。

拦截器代码 http://git.oschina.net/for-1988/gbh91frxjy6msalqp28vi.code.git