Question

我想创建List的自定义验证程序，以确保至少选择了两个项目。问题是，initialize和isValid方法都没有被调用过。如何使列表验证器工作？

我使用的是Java EE 7。

package com.sample.listvalidation;

import org.apache.commons.lang3.tuple.MutablePair;

import javax.annotation.PostConstruct;
import javax.faces.view.ViewScoped;
import javax.inject.Named;
import java.io.Serializable;
import java.util.Arrays;
import java.util.List;

@ViewScoped
@Named
public class Bean implements Serializable {

    @AtLeast2Selected
    private List<MutablePair<String, Boolean>> selection;

    public List<MutablePair<String, Boolean>> getSelection() {
        return selection;
    }

    public void setSelection(List<MutablePair<String, Boolean>> selection) {
        this.selection = selection;
    }

    @PostConstruct
    void init() {
        selection = Arrays.asList(
                MutablePair.of("a", true),
                MutablePair.of("b", true),
                MutablePair.of("c", false),
                MutablePair.of("d", false)
                );
    }

    public String validate() {
        return null;
    }
}

package com.sample.listvalidation;

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@Documented
@Constraint(validatedBy = AtLeast2SelectedValidator.class)
public @interface AtLeast2Selected {
    String message() default "At leaset 2 items have to be selected.";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

package com.sample.listvalidation;

import org.apache.commons.lang3.tuple.MutablePair;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.List;

public class AtLeast2SelectedValidator implements ConstraintValidator<AtLeast2Selected, List> {
    @Override
    public void initialize(AtLeast2Selected constraintAnnotation) {
        System.out.println("AtLeast2SelectedValidator.initialize");
    }

    @Override
    public boolean isValid(List value, ConstraintValidatorContext context) {
        System.out.println("AtLeast2SelectedValidator.isValid");
        if (value == null) {
            return false;
        }
        @SuppressWarnings("unchecked")
        final List<MutablePair<String, Boolean>> typedValue = (List<MutablePair<String, Boolean>>) value;
        return typedValue.stream()
                .filter(MutablePair::getRight)
                .count() >= 2;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://xmlns.jcp.org/jsf/html"
      xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
      xmlns:f="http://xmlns.jcp.org/jsf/core">
<f:view>
    <h:messages />
    <h:form>
        <h:dataTable value="#{bean.selection}" var="row">
            <h:column>
                <h:selectBooleanCheckbox value="#{row.right}" id="checkbox" />
            </h:column>
            <h:column>
                <h:outputLabel for="checkbox" value="#{row.left}" />
            </h:column>
        </h:dataTable>
        <h:commandButton value="validate" action="#{bean.validate}" />
    </h:form>
</f:view>
</html>

如何为List属性创建自定义BV约束验证器？

0 个答案: