在Controller方法中绑定到集合的Request estbody参数的Spring验证

Question

我有

一个实体：

package org.ibp.soq;

public class MyEntity {

    private String field1;
    private String field2;

    //..getters and setters

}

实体的验证器：

package org.ibp.soq;

import org.springframework.stereotype.Component;
import org.springframework.validation.Errors;
import org.springframework.validation.Validator;

@Component
public class MyEntityValidator implements Validator {

    @Override
    public boolean supports(Class<?> clazz) {
        return MyEntity.class.equals(clazz);
    }

    @Override
    public void validate(Object target, Errors errors) {
        MyEntity myEntity = (MyEntity) target;
        // Logic to validate my entity
        System.out.print(myEntity);
    }

}

和

采用批量PUT方法的REST控制器：

package org.ibp.soq;

import java.util.List;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/myEntity")
public class MyEntityRestResource {

    @Autowired
    private MyEntityValidator myEntityValidator;

    @InitBinder
    protected void initBinder(final WebDataBinder binder) {
        binder.addValidators(this.myEntityValidator);
    }

    @RequestMapping(method = RequestMethod.PUT)
    public void bulkCreate(@RequestBody @Valid List<MyEntity> myEntities) {
        // Logic to bulk create entities here.
        System.out.print(myEntities);
    }
}

当我使用以下请求正文对此资源发出PUT请求时：

[
  {
    "field1": "AA",
    "field2": "11"
  },

  {
    "field1": "BB",
    "field2": "22"
  }
]

我得到的错误是：

"Invalid target for Validator [org.ibp.soq.MyEntityValidator@4eab617e]: [org.ibp.soq.MyEntity@21cebf1c, org.ibp.soq.MyEntity@c64d89b]"

我可以理解，这是因为MyEntityValidator“支持”单个MyEntity验证，而不是对ArrayList的验证

如果在请求正文中有一个MyEntity对象和一个带有有效MyEntity MyEntity参数的相应控制器方法，则MyEntityValidator可以完美地工作。

如何扩展我使用的验证器设置，以支持MyEntity集合的验证？

Answer 1

实际上，这可以通过使用Spring验证和JSR303来实现。

• 公开MethodValidationPostProcessor bean
• 用@Validated（org.springframework.validation.annotation.Validated）注释控制器类
• 在MyEntity字段/方法上使用JSR303验证注释
• 用@Valid注释RequestBody参数（您已经在示例中这样做了）
• 添加@ExceptionHandler方法来处理MethodArgumentNotValidException。这可以在controller或@ControllerAdvice类中完成

Answer 2

正如您可能已经猜到的，使用Spring验证无法实现这一点。Spring验证实现Bean验证（JSR303/349），而不是对象验证。不幸的是，集合不是Java Bean。你有两个选择

• 把你的清单包在Java里
• 在您的批量创建方法myEntityValidator中手动调用验证器。验证（目标对象，错误）。

Answer 3

解决方案是为集合创建一个自定义的验证器，以及一个@ControllerAdvice在WebDataBinder中注册该验证器。

验证器：

import java.util.Collection;

import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;

/**
 * Spring {@link Validator} that iterates over the elements of a 
 * {@link Collection} and run the validation process for each of them
 * individually.
 *   
 * @author DISID CORPORATION S.L. (www.disid.com)
 */
public class CollectionValidator implements Validator {

  private final Validator validator;

  public CollectionValidator(LocalValidatorFactoryBean validatorFactory) {
    this.validator = validatorFactory;
  }

  @Override
  public boolean supports(Class<?> clazz) {
    return Collection.class.isAssignableFrom(clazz);
  }

  /**
   * Validate each element inside the supplied {@link Collection}.
   * 
   * The supplied errors instance is used to report the validation errors.
   * 
   * @param target the collection that is to be validated
   * @param errors contextual state about the validation process
   */
  @Override
  @SuppressWarnings("rawtypes")
  public void validate(Object target, Errors errors) {
    Collection collection = (Collection) target;
    for (Object object : collection) {
      ValidationUtils.invokeValidator(validator, object, errors);
    }
  }
}

控制器建议：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.InitBinder;

/**
 * Controller advice that adds the {@link CollectionValidator} to the 
 * {@link WebDataBinder}.
 * 
 * @author DISID CORPORATION S.L. (www.disid.com)
 */
@ControllerAdvice
public class ValidatorAdvice {

  @Autowired
  protected LocalValidatorFactoryBean validator;


  /**
   * Adds the {@link CollectionValidator} to the supplied 
   * {@link WebDataBinder}
   * 
   * @param binder web data binder.
   */
  @InitBinder
  public void initBinder(WebDataBinder binder) {
    binder.addValidators(new CollectionValidator(validator));
  }
}