在Hibernate Validator 4.x中是否有跨字段验证的实现(或第三方实现)?如果不是，实现跨字段验证器的最干净的方法是什么?
例如，如何使用API来验证两个bean属性是否相等(例如验证密码字段与密码验证字段是否匹配)。
在注释中，我期望如下内容:
public class MyBean {
@Size(min=6, max=50)
private String pass;
@Equals(property="pass")
private String passVerify;
}
当前回答
每个字段约束都应该由不同的验证器注释处理，或者换句话说，不建议使用一个字段的验证注释检查其他字段;跨域验证应该在类级别进行。此外，JSR-303第2.2节表示同一类型的多个验证的首选方法是通过注释列表。这允许在每次匹配时指定错误消息。
例如，验证一个公共表单:
@FieldMatch.List({
@FieldMatch(first = "password", second = "confirmPassword", message = "The password fields must match"),
@FieldMatch(first = "email", second = "confirmEmail", message = "The email fields must match")
})
public class UserRegistrationForm {
@NotNull
@Size(min=8, max=25)
private String password;
@NotNull
@Size(min=8, max=25)
private String confirmPassword;
@NotNull
@Email
private String email;
@NotNull
@Email
private String confirmEmail;
}
注释:
package constraints;
import constraints.impl.FieldMatchValidator;
import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.Documented;
import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.TYPE;
import java.lang.annotation.Retention;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Target;
/**
* Validation annotation to validate that 2 fields have the same value.
* An array of fields and their matching confirmation fields can be supplied.
*
* Example, compare 1 pair of fields:
* @FieldMatch(first = "password", second = "confirmPassword", message = "The password fields must match")
*
* Example, compare more than 1 pair of fields:
* @FieldMatch.List({
* @FieldMatch(first = "password", second = "confirmPassword", message = "The password fields must match"),
* @FieldMatch(first = "email", second = "confirmEmail", message = "The email fields must match")})
*/
@Target({TYPE, ANNOTATION_TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy = FieldMatchValidator.class)
@Documented
public @interface FieldMatch
{
String message() default "{constraints.fieldmatch}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
/**
* @return The first field
*/
String first();
/**
* @return The second field
*/
String second();
/**
* Defines several <code>@FieldMatch</code> annotations on the same element
*
* @see FieldMatch
*/
@Target({TYPE, ANNOTATION_TYPE})
@Retention(RUNTIME)
@Documented
@interface List
{
FieldMatch[] value();
}
}
验证器:
package constraints.impl;
import constraints.FieldMatch;
import org.apache.commons.beanutils.BeanUtils;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
public class FieldMatchValidator implements ConstraintValidator<FieldMatch, Object>
{
private String firstFieldName;
private String secondFieldName;
@Override
public void initialize(final FieldMatch constraintAnnotation)
{
firstFieldName = constraintAnnotation.first();
secondFieldName = constraintAnnotation.second();
}
@Override
public boolean isValid(final Object value, final ConstraintValidatorContext context)
{
try
{
final Object firstObj = BeanUtils.getProperty(value, firstFieldName);
final Object secondObj = BeanUtils.getProperty(value, secondFieldName);
return firstObj == null && secondObj == null || firstObj != null && firstObj.equals(secondObj);
}
catch (final Exception ignore)
{
// ignore
}
return true;
}
}
其他回答
我很惊讶这个没有开箱即用。不管怎样，这里有一个可能的解决方案。
我创建了一个类级验证器，而不是原始问题中描述的字段级验证器。
下面是注释代码:
package com.moa.podium.util.constraints;
import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import javax.validation.Constraint;
import javax.validation.Payload;
@Target({TYPE, ANNOTATION_TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy = MatchesValidator.class)
@Documented
public @interface Matches {
String message() default "{com.moa.podium.util.constraints.matches}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
String field();
String verifyField();
}
以及验证器本身:
package com.moa.podium.util.constraints;
import org.mvel2.MVEL;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
public class MatchesValidator implements ConstraintValidator<Matches, Object> {
private String field;
private String verifyField;
public void initialize(Matches constraintAnnotation) {
this.field = constraintAnnotation.field();
this.verifyField = constraintAnnotation.verifyField();
}
public boolean isValid(Object value, ConstraintValidatorContext context) {
Object fieldObj = MVEL.getProperty(field, value);
Object verifyFieldObj = MVEL.getProperty(verifyField, value);
boolean neitherSet = (fieldObj == null) && (verifyFieldObj == null);
if (neitherSet) {
return true;
}
boolean matches = (fieldObj != null) && fieldObj.equals(verifyFieldObj);
if (!matches) {
context.disableDefaultConstraintViolation();
context.buildConstraintViolationWithTemplate("message")
.addNode(verifyField)
.addConstraintViolation();
}
return matches;
}
}
注意，我已经使用MVEL来检查正在验证的对象的属性。这可以用标准反射api代替，或者如果它是您正在验证的特定类，则使用访问器方法本身。
@Matches注释可以像下面这样使用在bean上:
@Matches(field="pass", verifyField="passRepeat")
public class AccountCreateForm {
@Size(min=6, max=50)
private String pass;
private String passRepeat;
...
}
作为免责声明，我在最后5分钟写了这篇文章，所以我可能还没有解决所有的错误。如果有任何错误，我将更新答案。
您需要显式地调用它。在上面的例子中，bradhouse给出了编写自定义约束的所有步骤。
在调用者类中添加此代码。
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
validator = factory.getValidator();
Set<ConstraintViolation<yourObjectClass>> constraintViolations = validator.validate(yourObject);
在上述情况下，它将是
Set<ConstraintViolation<AccountCreateForm>> constraintViolations = validator.validate(objAccountCreateForm);
我喜欢Jakub Jirutka使用Spring表达式语言的想法。如果您不想添加另一个库/依赖项(假设您已经使用了Spring)，下面是他的想法的简化实现。
约束:
@Constraint(validatedBy=ExpressionAssertValidator.class)
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface ExpressionAssert {
String message() default "expression must evaluate to true";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
String value();
}
验证器:
public class ExpressionAssertValidator implements ConstraintValidator<ExpressionAssert, Object> {
private Expression exp;
public void initialize(ExpressionAssert annotation) {
ExpressionParser parser = new SpelExpressionParser();
exp = parser.parseExpression(annotation.value());
}
public boolean isValid(Object value, ConstraintValidatorContext context) {
return exp.getValue(value, Boolean.class);
}
}
像这样应用:
@ExpressionAssert(value="pass == passVerify", message="passwords must be same")
public class MyBean {
@Size(min=6, max=50)
private String pass;
private String passVerify;
}
为什么不试试Oval: http://oval.sourceforge.net/呢
我看起来像它支持OGNL，所以也许你可以用更自然的方式来做
@Assert(expr = "_value ==_this.pass").
使用Hibernate Validator 4.1.0。最后，我建议使用@ScriptAssert。除了它的JavaDoc:
脚本表达式可以用任何脚本或表达式编写 JSR 223(“java平台脚本编写”) 兼容的引擎可以在类路径中找到。
注意:评估是由运行在Java VM中的脚本“引擎”执行的，因此是在Java“服务器端”，而不是在某些注释中所述的“客户端”。
例子:
@ScriptAssert(lang = "javascript", script = "_this.passVerify.equals(_this.pass)")
public class MyBean {
@Size(min=6, max=50)
private String pass;
private String passVerify;
}
或者使用更短的别名和null安全:
@ScriptAssert(lang = "javascript", alias = "_",
script = "_.passVerify != null && _.passVerify.equals(_.pass)")
public class MyBean {
@Size(min=6, max=50)
private String pass;
private String passVerify;
}
或者使用Java 7+ null-safe Objects.equals():
@ScriptAssert(lang = "javascript", script = "Objects.equals(_this.passVerify, _this.pass)")
public class MyBean {
@Size(min=6, max=50)
private String pass;
private String passVerify;
}
尽管如此，自定义类级验证器@Matches解决方案并没有什么问题。
