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);

我建议你另一种可能的解决办法。也许不那么优雅，但更容易!

public class MyBean {
  @Size(min=6, max=50)
  private String pass;

  private String passVerify;

  @NotNull
  private LocalDate passExpiry;
  @NotNull
  private LocalDate dateOfJoining;

  @AssertTrue(message = "Fields `pass` and `passVerify` should be equal")
  // Any method name is ok als long it begins with `is`
  private boolean isValidPass() {
    //return pass == null && passVerify == null || pass.equals(passVerify);
    // Since Java 7:
    return Objects.equals(pass, passVerify);
  }

  @AssertTrue(message = "Field `passExpiry` should be later than `dateOfJoining`")
  // Other rules can also be validated in other methods
  private boolean isPassExpiryAfterDateOfJoining() {
    return dateOfJoining.isBefore(passExpiry);
  }
}

isValid()和isPassExpiryAfterDateOfJoining()方法由验证器自动调用。在ConstraintViolations中报告的属性路径将从方法名中提取:valid和passExpiryAfterDateOfJoining。

非常好的解决方案，布拉德豪斯。是否有办法将@Matches注释应用到多个字段?

编辑: 下面是我想出的解决方案来回答这个问题，我修改了约束以接受数组而不是单个值:

@Matches(fields={"password", "email"}, verifyFields={"confirmPassword", "confirmEmail"})
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;
}

注释的代码:

package springapp.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 "{springapp.util.constraints.matches}";

  Class<?>[] groups() default {};

  Class<? extends Payload>[] payload() default {};

  String[] fields();

  String[] verifyFields();
}

以及实现:

package springapp.util.constraints;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

import org.apache.commons.beanutils.BeanUtils;

public class MatchesValidator implements ConstraintValidator<Matches, Object> {

    private String[] fields;
    private String[] verifyFields;

    public void initialize(Matches constraintAnnotation) {
        fields = constraintAnnotation.fields();
        verifyFields = constraintAnnotation.verifyFields();
    }

    public boolean isValid(Object value, ConstraintValidatorContext context) {

        boolean matches = true;

        for (int i=0; i<fields.length; i++) {
            Object fieldObj, verifyFieldObj;
            try {
                fieldObj = BeanUtils.getProperty(value, fields[i]);
                verifyFieldObj = BeanUtils.getProperty(value, verifyFields[i]);
            } catch (Exception e) {
                //ignore
                continue;
            }
            boolean neitherSet = (fieldObj == null) && (verifyFieldObj == null);
            if (neitherSet) {
                continue;
            }

            boolean tempMatches = (fieldObj != null) && fieldObj.equals(verifyFieldObj);

            if (!tempMatches) {
                addConstraintViolation(context, fields[i]+ " fields do not match", verifyFields[i]);
            }

            matches = matches?tempMatches:matches;
        }
        return matches;
    }

    private void addConstraintViolation(ConstraintValidatorContext context, String message, String field) {
        context.disableDefaultConstraintViolation();
        context.buildConstraintViolationWithTemplate(message).addNode(field).addConstraintViolation();
    }
}

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;
    }
}

我尝试了Alberthoven的例子(hibernate-validator 4.0.2.GA)，我得到了一个ValidationException:“带注释的方法必须遵循JavaBeans命名约定。Match()没有。”。在我将方法从“match”重命名为“isValid”后，它就工作了。

public class Password {

    private String password;

    private String retypedPassword;

    public Password(String password, String retypedPassword) {
        super();
        this.password = password;
        this.retypedPassword = retypedPassword;
    }

    @AssertTrue(message="password should match retyped password")
    private boolean isValid(){
        if (password == null) {
            return retypedPassword == null;
        } else {
            return password.equals(retypedPassword);
        }
    }

    public String getPassword() {
        return password;
    }

    public String getRetypedPassword() {
        return retypedPassword;
    }

}

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。

跨字段验证可以通过创建自定义约束来完成。

举例:—比较User实例的password和confirmPassword字段。

比较字符串

@Target({TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy=CompareStringsValidator.class)
@Documented
public @interface CompareStrings {
    String[] propertyNames();
    StringComparisonMode matchMode() default EQUAL;
    boolean allowNull() default false;
    String message() default "";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

StringComparisonMode

public enum StringComparisonMode {
    EQUAL, EQUAL_IGNORE_CASE, NOT_EQUAL, NOT_EQUAL_IGNORE_CASE
}

CompareStringsValidator

public class CompareStringsValidator implements ConstraintValidator<CompareStrings, Object> {

    private String[] propertyNames;
    private StringComparisonMode comparisonMode;
    private boolean allowNull;

    @Override
    public void initialize(CompareStrings constraintAnnotation) {
        this.propertyNames = constraintAnnotation.propertyNames();
        this.comparisonMode = constraintAnnotation.matchMode();
        this.allowNull = constraintAnnotation.allowNull();
    }

    @Override
    public boolean isValid(Object target, ConstraintValidatorContext context) {
        boolean isValid = true;
        List<String> propertyValues = new ArrayList<String> (propertyNames.length);
        for(int i=0; i<propertyNames.length; i++) {
            String propertyValue = ConstraintValidatorHelper.getPropertyValue(String.class, propertyNames[i], target);
            if(propertyValue == null) {
                if(!allowNull) {
                    isValid = false;
                    break;
                }
            } else {
                propertyValues.add(propertyValue);
            }
        }

        if(isValid) {
            isValid = ConstraintValidatorHelper.isValid(propertyValues, comparisonMode);
        }

        if (!isValid) {
          /*
           * if custom message was provided, don't touch it, otherwise build the
           * default message
           */
          String message = context.getDefaultConstraintMessageTemplate();
          message = (message.isEmpty()) ?  ConstraintValidatorHelper.resolveMessage(propertyNames, comparisonMode) : message;

          context.disableDefaultConstraintViolation();
          ConstraintViolationBuilder violationBuilder = context.buildConstraintViolationWithTemplate(message);
          for (String propertyName : propertyNames) {
            NodeBuilderDefinedContext nbdc = violationBuilder.addNode(propertyName);
            nbdc.addConstraintViolation();
          }
        }    

        return isValid;
    }
}

约束验证器助手

public abstract class ConstraintValidatorHelper {

public static <T> T getPropertyValue(Class<T> requiredType, String propertyName, Object instance) {
        if(requiredType == null) {
            throw new IllegalArgumentException("Invalid argument. requiredType must NOT be null!");
        }
        if(propertyName == null) {
            throw new IllegalArgumentException("Invalid argument. PropertyName must NOT be null!");
        }
        if(instance == null) {
            throw new IllegalArgumentException("Invalid argument. Object instance must NOT be null!");
        }
        T returnValue = null;
        try {
            PropertyDescriptor descriptor = new PropertyDescriptor(propertyName, instance.getClass());
            Method readMethod = descriptor.getReadMethod();
            if(readMethod == null) {
                throw new IllegalStateException("Property '" + propertyName + "' of " + instance.getClass().getName() + " is NOT readable!");
            }
            if(requiredType.isAssignableFrom(readMethod.getReturnType())) {
                try {
                    Object propertyValue = readMethod.invoke(instance);
                    returnValue = requiredType.cast(propertyValue);
                } catch (Exception e) {
                    e.printStackTrace(); // unable to invoke readMethod
                }
            }
        } catch (IntrospectionException e) {
            throw new IllegalArgumentException("Property '" + propertyName + "' is NOT defined in " + instance.getClass().getName() + "!", e);
        }
        return returnValue; 
    }

    public static boolean isValid(Collection<String> propertyValues, StringComparisonMode comparisonMode) {
        boolean ignoreCase = false;
        switch (comparisonMode) {
        case EQUAL_IGNORE_CASE:
        case NOT_EQUAL_IGNORE_CASE:
            ignoreCase = true;
        }

        List<String> values = new ArrayList<String> (propertyValues.size());
        for(String propertyValue : propertyValues) {
            if(ignoreCase) {
                values.add(propertyValue.toLowerCase());
            } else {
                values.add(propertyValue);
            }
        }

        switch (comparisonMode) {
        case EQUAL:
        case EQUAL_IGNORE_CASE:
            Set<String> uniqueValues = new HashSet<String> (values);
            return uniqueValues.size() == 1 ? true : false;
        case NOT_EQUAL:
        case NOT_EQUAL_IGNORE_CASE:
            Set<String> allValues = new HashSet<String> (values);
            return allValues.size() == values.size() ? true : false;
        }

        return true;
    }

    public static String resolveMessage(String[] propertyNames, StringComparisonMode comparisonMode) {
        StringBuffer buffer = concatPropertyNames(propertyNames);
        buffer.append(" must");
        switch(comparisonMode) {
        case EQUAL:
        case EQUAL_IGNORE_CASE:
            buffer.append(" be equal");
            break;
        case NOT_EQUAL:
        case NOT_EQUAL_IGNORE_CASE:
            buffer.append(" not be equal");
            break;
        }
        buffer.append('.');
        return buffer.toString();
    }

    private static StringBuffer concatPropertyNames(String[] propertyNames) {
        //TODO improve concating algorithm
        StringBuffer buffer = new StringBuffer();
        buffer.append('[');
        for(String propertyName : propertyNames) {
            char firstChar = Character.toUpperCase(propertyName.charAt(0));
            buffer.append(firstChar);
            buffer.append(propertyName.substring(1));
            buffer.append(", ");
        }
        buffer.delete(buffer.length()-2, buffer.length());
        buffer.append("]");
        return buffer;
    }
}

User

@CompareStrings(propertyNames={"password", "confirmPassword"})
public class User {
    private String password;
    private String confirmPassword;

    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
    public String getConfirmPassword() { return confirmPassword; }
    public void setConfirmPassword(String confirmPassword) { this.confirmPassword =  confirmPassword; }
}

Test

    public void test() {
        User user = new User();
        user.setPassword("password");
        user.setConfirmPassword("paSSword");
        Set<ConstraintViolation<User>> violations = beanValidator.validate(user);
        for(ConstraintViolation<User> violation : violations) {
            logger.debug("Message:- " + violation.getMessage());
        }
        Assert.assertEquals(violations.size(), 1);
    }

输出信息:—[Password, ConfirmPassword]必须相等。

通过使用CompareStrings验证约束，我们还可以比较两个以上的属性，并且可以混合使用四种字符串比较方法中的任何一种。

ColorChoice

@CompareStrings(propertyNames={"color1", "color2", "color3"}, matchMode=StringComparisonMode.NOT_EQUAL, message="Please choose three different colors.")
public class ColorChoice {

    private String color1;
    private String color2;
    private String color3;
        ......
}

Test

ColorChoice colorChoice = new ColorChoice();
        colorChoice.setColor1("black");
        colorChoice.setColor2("white");
        colorChoice.setColor3("white");
        Set<ConstraintViolation<ColorChoice>> colorChoiceviolations = beanValidator.validate(colorChoice);
        for(ConstraintViolation<ColorChoice> violation : colorChoiceviolations) {
            logger.debug("Message:- " + violation.getMessage());
        }

输出信息:—请选择三种不同的颜色。

类似地，我们可以有CompareNumbers、CompareDates等跨字段验证约束。

附注:我没有在生产环境下测试此代码(尽管我在开发环境下测试了它)，所以将此代码视为里程碑发布。如果你发现一个bug，请写一个好的评论。：）

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").

如果您正在使用Spring框架，那么您可以使用Spring表达式语言(SpEL)。我写了一个小库，提供了基于SpEL的JSR-303验证器——它使得跨领域验证变得轻而易举!看看https://github.com/jirutka/validator-spring。

这将验证密码字段的长度和相等性。

@SpELAssert(value = "pass.equals(passVerify)",
            message = "{validator.passwords_not_same}")
public class MyBean {

    @Size(min = 6, max = 50)
    private String pass;

    private String passVerify;
}

您还可以轻松地进行修改，仅当密码字段不为空时才验证密码字段。

@SpELAssert(value = "pass.equals(passVerify)",
            applyIf = "pass || passVerify",
            message = "{validator.passwords_not_same}")
public class MyBean {

    @Size(min = 6, max = 50)
    private String pass;

    private String passVerify;
}

我没有评论第一个答案的名声，但我想补充的是，我已经为获胜的答案添加了单元测试，并有以下观察:

如果第一个或字段名出错，就会出现验证错误，就好像值不匹配一样。不要被拼写错误绊倒。

@FieldMatch（first=“invalidFieldName1”， second=“validFieldName2”）

验证器将接受等效的数据类型，即这些都将通过FieldMatch:

private String stringField = "1"; private Integer integerField = new Integer(1) private int intField = 1;

如果字段的对象类型没有实现equals，则验证将失败。

你们太棒了。真是惊人的想法。我最喜欢阿尔伯托芬和麦金的，所以我决定把他们的想法结合起来。并开发一些通用的解决方案，以满足所有情况。以下是我提出的解决方案。

@Documented
@Constraint(validatedBy = NotFalseValidator.class)
@Target({ElementType.METHOD, ElementType.FIELD,ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface NotFalse {


    String message() default "NotFalse";
    String[] messages();
    String[] properties();
    String[] verifiers();

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

}

public class NotFalseValidator implements ConstraintValidator<NotFalse, Object> {
    private String[] properties;
    private String[] messages;
    private String[] verifiers;
    @Override
    public void initialize(NotFalse flag) {
        properties = flag.properties();
        messages = flag.messages();
        verifiers = flag.verifiers();
    }

    @Override
    public boolean isValid(Object bean, ConstraintValidatorContext cxt) {
        if(bean == null) {
            return true;
        }

        boolean valid = true;
        BeanWrapper beanWrapper = PropertyAccessorFactory.forBeanPropertyAccess(bean);

        for(int i = 0; i< properties.length; i++) {
           Boolean verified = (Boolean) beanWrapper.getPropertyValue(verifiers[i]);
           valid &= isValidProperty(verified,messages[i],properties[i],cxt);
        }

        return valid;
    }

    boolean isValidProperty(Boolean flag,String message, String property, ConstraintValidatorContext cxt) {
        if(flag == null || flag) {
            return true;
        } else {
            cxt.disableDefaultConstraintViolation();
            cxt.buildConstraintViolationWithTemplate(message)
                    .addPropertyNode(property)
                    .addConstraintViolation();
            return false;
        }

    }



}

@NotFalse(
        messages = {"End Date Before Start Date" , "Start Date Before End Date" } ,
        properties={"endDateTime" , "startDateTime"},
        verifiers = {"validDateRange" , "validDateRange"})
public class SyncSessionDTO implements ControllableNode {
    @NotEmpty @NotPastDate
    private Date startDateTime;

    @NotEmpty
    private Date endDateTime;



    public Date getStartDateTime() {
        return startDateTime;
    }

    public void setStartDateTime(Date startDateTime) {
        this.startDateTime = startDateTime;
    }

    public Date getEndDateTime() {
        return endDateTime;
    }

    public void setEndDateTime(Date endDateTime) {
        this.endDateTime = endDateTime;
    }


    public Boolean getValidDateRange(){
        if(startDateTime != null && endDateTime != null) {
            return startDateTime.getTime() <= endDateTime.getTime();
        }

        return null;
    }

}

与问题相关的解决方案: 如何访问在注释属性中描述的字段

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Match {

    String field();

    String message() default "";
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = MatchValidator.class)
@Documented
public @interface EnableMatchConstraint {

    String message() default "Fields must match!";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};
}

public class MatchValidator implements  ConstraintValidator<EnableMatchConstraint, Object> {

    @Override
    public void initialize(final EnableMatchConstraint constraint) {}

    @Override
    public boolean isValid(final Object o, final ConstraintValidatorContext context) {
        boolean result = true;
        try {
            String mainField, secondField, message;
            Object firstObj, secondObj;

            final Class<?> clazz = o.getClass();
            final Field[] fields = clazz.getDeclaredFields();

            for (Field field : fields) {
                if (field.isAnnotationPresent(Match.class)) {
                    mainField = field.getName();
                    secondField = field.getAnnotation(Match.class).field();
                    message = field.getAnnotation(Match.class).message();

                    if (message == null || "".equals(message))
                        message = "Fields " + mainField + " and " + secondField + " must match!";

                    firstObj = BeanUtils.getProperty(o, mainField);
                    secondObj = BeanUtils.getProperty(o, secondField);

                    result = firstObj == null && secondObj == null || firstObj != null && firstObj.equals(secondObj);
                    if (!result) {
                        context.disableDefaultConstraintViolation();
                        context.buildConstraintViolationWithTemplate(message).addPropertyNode(mainField).addConstraintViolation();
                        break;
                    }
                }
            }
        } catch (final Exception e) {
            // ignore
            //e.printStackTrace();
        }
        return result;
    }
}

如何使用它?是这样的:

@Entity
@EnableMatchConstraint
public class User {

    @NotBlank
    private String password;

    @Match(field = "password")
    private String passwordConfirmation;
}

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;
}

我在Nicko的解决方案中做了一个小的调整，这样就没有必要使用Apache Commons BeanUtils库，并将其替换为春季已经可用的解决方案，对于那些使用它的人来说，我可以更简单:

import org.springframework.beans.BeanWrapper;
import org.springframework.beans.PropertyAccessorFactory;

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 object, final ConstraintValidatorContext context) {

        BeanWrapper beanWrapper = PropertyAccessorFactory.forBeanPropertyAccess(object);
        final Object firstObj = beanWrapper.getPropertyValue(firstFieldName);
        final Object secondObj = beanWrapper.getPropertyValue(secondFieldName);

        boolean isValid = firstObj == null && secondObj == null || firstObj != null && firstObj.equals(secondObj);

        if (!isValid) {
            context.disableDefaultConstraintViolation();
            context.buildConstraintViolationWithTemplate(context.getDefaultConstraintMessageTemplate())
                .addPropertyNode(firstFieldName)
                .addConstraintViolation();
        }

        return isValid;

    }
}