springMVC引入Validation的具体步骤详解

2024-07-14 08:40:54

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本文简单介绍如何引入validation的步骤，如何通过自定义validation减少代码量，提高生产力。特别提及：非基本类型属性的valid，GET方法的处理，validation错误信息的统一resolve。

本文中validation的实际实现委托给Hibernate validation处理

基本配置

pom引入maven依赖

<!-- validation begin --><dependency>  <groupId>javax.validation</groupId>  <artifactId>validation-api</artifactId>  <version>1.1.0.Final</version></dependency><dependency>  <groupId>org.hibernate</groupId>  <artifactId>hibernate-validator</artifactId>  <version>5.4.0.Final</version></dependency><!-- validation end -->

增加validation配置

在spring-mvc-servlet.xml中增加如下配置:

<mvc:annotation-driven validator="validator"><bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean">  <property name="providerClass" value="org.hibernate.validator.HibernateValidator" />  <property name="validationMessageSource" ref="messageSource"/></bean>//messageSource 为i18n资源管理bean，见applicationContext.xml配置

自定义exceptionHandler

个性化处理validation错误信息,返回给调用方的信息更加友好，在applicationContext.xml中增加如下配置:

<!-- 加载i18n消息资源文件 --><bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">  <property name="basenames">    <list>      <value>errormsg</value>      <value>validation_error</value>    </list>  </property></bean><bean id="validationExceptionResolver" class="com.*.exception.ValidationExceptionResovler"/>

在项目类路径上增加：validation_error_zh_CN.properties资源文件：

#the error msg for input validation#commonfield.can.not.be.null={field}不能为空field.can.not.be.empty={field}不能为空或者空字符串field.must.be.greater.than.min={field}不能小于{value}field.must.be.letter.than.max={field}不能大于{value}

ValidationExceptionResovler实现：

ValidationExceptionResovler.java

@Slf4jpublic class ValidationExceptionResovler extends AbstractHandlerExceptionResolver {  public ValidationExceptionResovler() {    // 设置order，在DefaultHandlerExceptionResolver之前执行    this.setOrder(0);  }  /**   * Handle the case where an argument annotated with {@code @Valid} such as   * an {@link } or {@link } argument fails validation.   * <p>   * 自定义ValidationException 异常处理器   * 获取到具体的validation 错误信息，并组装CommonResponse，返回给调用方。   *   * @param request current HTTP request   * @param response current HTTP response   * @param handler the executed handler   * @return an empty ModelAndView indicating the exception was handled   * @throws IOException potentially thrown from response.sendError()   */  @ResponseBody  protected ModelAndView handleMethodArgumentNotValidException(BindingResult bindingResult,                                 HttpServletRequest request,                                 HttpServletResponse response,                                 Object handler)      throws IOException {    List<ObjectError> errors = bindingResult.getAllErrors();    StringBuffer errmsgBF = new StringBuffer();    for (ObjectError error : errors) {      String massage = error.getDefaultMessage();      errmsgBF.append(massage);      errmsgBF.append("||");    }    String errmsgString = errmsgBF.toString();    errmsgString = errmsgString.length() > 2 ? errmsgString.substring(0, errmsgString.length() - 2) : errmsgString;    log.error("Validation failed! {} ", errmsgString);    Map<String, Object> map = new TreeMap<String, Object>();    map.put("success", false);    map.put("errorCode", "9999");    map.put("errorMsg", errmsgString);    ModelAndView mav = new ModelAndView();    MappingJackson2JsonView view = new MappingJackson2JsonView();    view.setAttributesMap(map);    mav.setView(view);    return mav;  }  @Override  protected ModelAndView doResolveException(HttpServletRequest request,                       HttpServletResponse response, Object handler,                       Exception ex) {    BindingResult bindingResult = null;    if (ex instanceof MethodArgumentNotValidException) {      bindingResult = ((MethodArgumentNotValidException) ex).getBindingResult();    } else if(ex instanceof BindException) {      bindingResult = ((BindException) ex).getBindingResult();    } else {      //other exception , ignore    }    if(bindingResult != null) {      try {        return handleMethodArgumentNotValidException(bindingResult, request, response, handler);      } catch (IOException e) {        log.error("doResolveException: ", e);      }    }    return null;  }}

在controller中增加@Valid

@RequestMapping("/buy")@ResponseBodypublic BaseResponse buy(@RequestBody @Valid BuyFlowerRequest request) throws Exception { //......}

在request bean上为需要validation的属性增加validation注解

@Setter@Getterpublic class BuyFlowerRequest {@NotEmpty(message = "{name.can.not.be.null}") private String name;}

二级对象的validation

上面的写法，只能对BuyFlowerRequest在基本类型属性上做校验,但是没有办法对对象属性的属性进行validation,如果需要对二级对象的属性进行validation,则需要在二级对象及二级对象属性上同时添加@Valid 和具体的validation注解.

如下写法:

@Setter@Getterpublic class BuyFlowerRequest {  @NotEmpty(field = "花名")  private String name;  @Min(field = "价格", value = 1)  private int price;  @NotNull  private List<PayType> payTypeList;} @Setter@Getterpublic class PayType {  @Valid  @Min(value = 1)  private int payType;  @Valid  @Min(value = 1)  private int payAmount;}

进一步减少编码量

为了减少编码工作量,通过自定义Validation注解,尝试将validation作用的filed名称传递到错误信息的资源文件中,从而避免为每个域编写不同的message模版.

下面以重写的@NotNull为例讲解:

1、定义Validation注解,注意相比原生注解增加了field(),用于传递被validated的filed名字

NotNull.java

@Target( { ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.PARAMETER })@Constraint(validatedBy = { NotNullValidator.class })@Retention(RetentionPolicy.RUNTIME)public @interface NotNull {  String field() default "";  String message() default "{field.can.not.be.null}";  Class<?>[] groups() default {};  Class<? extends Payload>[] payload() default {};}

2、定义Validator,所有的Validator均实现ConstraintValidator接口:

NotNullValidator.java

public class NotNullValidator implements ConstraintValidator<NotNull, Object> {  @Override  public void initialize(NotNull annotation) {  }  @Override  public boolean isValid(Object str, ConstraintValidatorContext constraintValidatorContext) {    return str != null;  }}

3、在filed上加入Validation注解,注意指定filed值,message如果没有个性化需求，可以不用指明，validation组件会自行填充default message。

BuyFlowerRequest.java

@Setter@Getterpublic class BuyFlowerRequest {  @NotEmpty(field = "花名")  private String name;  @Min(field = "价格", value = 1)  private int price;}

注：@NotNull注解已经支持对list的特殊校验，对于List类型节点，如果list==null || list.size() == 0都会返回false，validation失败。目前已按照此思路自定义实现了@NotNull、@NotEmpty、@Min、@Max注解,在goods工程中可以找到.

支持GET请求

上面的示例都是POST请求，@RequestBody可以 resolve POST请求，但是不支持GET请求，阅读spring的文档和源码，发现@ModelAttribute可以将GET请求resolve成Bean，且支持Validation。具体可以翻阅spring源码：ModelAttributeMethodProcessor.resolveArgument()方法。

使用示例：

@RequestMapping(value = "/buy", method = RequestMethod.GET)@ResponseBodypublic BaseResponse detail(@Valid @ModelAttribute DetailFlowerRequest request) throws Exception {  DetailFlowerResponse response = new DetailFlowerResponse();  response.setName(request.getName());  return ResultFactory.success(response, BaseResponse.class);}

TODO

1、根据业务场景扩展validation,如:日期格式、金额等

2、支持多个field关系校验的validation

附：spring validation实现关键代码

@RequestBody

实现类：RequestResponseBodyMethodProcessor.java

public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception { Object arg = this.readWithMessageConverters(webRequest, parameter, parameter.getGenericParameterType()); String name = Conventions.getVariableNameForParameter(parameter); WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name); if (arg != null) { this.validateIfApplicable(binder, parameter); if (binder.getBindingResult().hasErrors() && this.isBindExceptionRequired(binder, parameter)) {  throw new MethodArgumentNotValidException(parameter, binder.getBindingResult()); } } mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult()); return arg;}

@ModelAttibute

实现类：ModelAttributeMethodProcessor.java

public final Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception { String name = ModelFactory.getNameForParameter(parameter); Object attribute = mavContainer.containsAttribute(name) ? mavContainer.getModel().get(name) : this.createAttribute(name, parameter, binderFactory, webRequest); if (!mavContainer.isBindingDisabled(name)) { ModelAttribute ann = (ModelAttribute)parameter.getParameterAnnotation(ModelAttribute.class); if (ann != null && !ann.binding()) {  mavContainer.setBindingDisabled(name); } } WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name); if (binder.getTarget() != null) { if (!mavContainer.isBindingDisabled(name)) {  this.bindRequestParameters(binder, webRequest); } this.validateIfApplicable(binder, parameter); if (binder.getBindingResult().hasErrors() && this.isBindExceptionRequired(binder, parameter)) {  throw new BindException(binder.getBindingResult()); } } Map<String, Object> bindingResultModel = binder.getBindingResult().getModel(); mavContainer.removeAttributes(bindingResultModel); mavContainer.addAllAttributes(bindingResultModel); return binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);}

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