Struts2 Bean级验证

今天解决Struts2 Action 级验证当 属性为null时也验证的问题。
测试发现，Struts2 Action 级验证，当被验证的Action中的属性没有被注入值得时候，即是为null的时候，也会执行验证，输出验证信息，估计是因为有必选验证，ognl判断的时候有容错，防止因为属性本身是null，而出异常  ，返回了null， 比如验证实体类中的某个属性，8大基本类型的封装类型和String就不必说了，ognl取值的时候一定返回null。




关于Action级验证和Bean级验证的介绍 ： http://kin111.blog.51cto.com/738881/167181 ， 大家可以参考。


官方的示例： http://struts.apache.org/release/2.3.x/docs/using-visitor-field-validator.html

上面两个文章中可以看到，Bean级验证就是在Action验证文件里写个visitor验证器的xml，然后再 被验证的 Bean 类所在的包下再一个Bean的验证Xml （放在其他地方会找不到这个验证的配置，struts2就会跳过，而不会出异常！）

VisitorFieldValidator 的源码，就是visitor验证器的实现类

/* * Copyright 2002-2006,2009 The Apache Software Foundation. *  * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at *  *      http://www.apache.org/licenses/LICENSE-2.0 *  * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.opensymphony.xwork2.validator.validators;import com.opensymphony.xwork2.ActionContext;import com.opensymphony.xwork2.inject.Inject;import com.opensymphony.xwork2.util.ValueStack;import com.opensymphony.xwork2.validator.ActionValidatorManager;import com.opensymphony.xwork2.validator.DelegatingValidatorContext;import com.opensymphony.xwork2.validator.ValidationException;import com.opensymphony.xwork2.validator.ValidatorContext;import java.util.Collection;/** * <!-- START SNIPPET: javadoc --> * The VisitorFieldValidator allows you to forward validation to object * properties of your action using the object's own validation files.  This * allows you to use the ModelDriven development pattern and manage your * validations for your models in one place, where they belong, next to your * model classes.  The VisitorFieldValidator can handle either simple Object * properties, Collections of Objects, or Arrays. * <!-- END SNIPPET: javadoc --> * <p/> * * <!-- START SNIPPET: parameters --> * <ul> * <li>fieldName - field name if plain-validator syntax is used, not needed if field-validator syntax is used</li> * <li>context - the context of which validation should take place. Optional</li> * <li>appendPrefix - the prefix to be added to field. Optional </li> * </ul> * <!-- END SNIPPET: parameters --> * * <pre> * <!-- START SNIPPET: example --> *    <validators> *        <!-- Plain Validator Syntax --> *        <validator type="visitor"> *            <param name="fieldName">user</param> *            <param name="context">myContext</param> *            <param name="appendPrefix">true</param> *        </validator> * *        <!-- Field Validator Syntax --> *        <field name="user"> *           <field-validator type="visitor"> *              <param name="context">myContext</param> *              <param name="appendPrefix">true</param> *           </field-validator> *        </field> *    </validators> * <!-- END SNIPPET: example --> * </pre> * * <!-- START SNIPPET: explanation --> * <p>In the example above, if the acion's getUser() method return User object, XWork * will look for User-myContext-validation.xml for the validators. Since appednPrefix is true, * every field name will be prefixed with 'user' such that if the actual field name for 'name' is * 'user.name' </p> * <!-- END SNIPPET: explanation --> * * @author Jason Carreira * @author Rainer Hermanns * @version $Date: 2009-12-27 19:18:29 +0100 (Sun, 27 Dec 2009) $ $Id: VisitorFieldValidator.java 894090 2009-12-27 18:18:29Z martinc $ */public class VisitorFieldValidator extends FieldValidatorSupport {    private String context;    private boolean appendPrefix = true;    private ActionValidatorManager actionValidatorManager;    @Inject    public void setActionValidatorManager(ActionValidatorManager mgr) {        this.actionValidatorManager = mgr;    }    /**     * Sets whether the field name of this field validator should be prepended to the field name of     * the visited field to determine the full field name when an error occurs.  The default is     * true.     */    public void setAppendPrefix(boolean appendPrefix) {        this.appendPrefix = appendPrefix;    }    /**     * Flags whether the field name of this field validator should be prepended to the field name of     * the visited field to determine the full field name when an error occurs.  The default is     * true.     */    public boolean isAppendPrefix() {        return appendPrefix;    }    public void setContext(String context) {        this.context = context;    }    public String getContext() {        return context;    }    public void validate(Object object) throws ValidationException {        String fieldName = getFieldName();        Object value = this.getFieldValue(fieldName, object);        if (value == null) {            log.warn("The visited object is null, VisitorValidator will not be able to handle validation properly. Please make sure the visited object is not null for VisitorValidator to function properly");            return;        }        ValueStack stack = ActionContext.getContext().getValueStack();        stack.push(object);        String visitorContext = (context == null) ? ActionContext.getContext().getName() : context;        if (value instanceof Collection) {            Collection coll = (Collection) value;            Object[] array = coll.toArray();            validateArrayElements(array, fieldName, visitorContext);        } else if (value instanceof Object[]) {            Object[] array = (Object[]) value;            validateArrayElements(array, fieldName, visitorContext);        } else {            validateObject(fieldName, value, visitorContext);        }        stack.pop();    }    private void validateArrayElements(Object[] array, String fieldName, String visitorContext) throws ValidationException {        if (array == null) {            return;        }        for (int i = 0; i < array.length; i++) {            Object o = array[i];            if (o != null) {                validateObject(fieldName + "[" + i + "]", o, visitorContext);            }        }    }    private void validateObject(String fieldName, Object o, String visitorContext) throws ValidationException {        ValueStack stack = ActionContext.getContext().getValueStack();        stack.push(o);        ValidatorContext validatorContext;        if (appendPrefix) {            validatorContext = new AppendingValidatorContext(getValidatorContext(), o, fieldName, getMessage(o));        } else {            ValidatorContext parent = getValidatorContext();            validatorContext = new DelegatingValidatorContext(parent, DelegatingValidatorContext.makeTextProvider(o, parent), parent);        }        actionValidatorManager.validate(o, visitorContext, validatorContext);        stack.pop();    }    public static class AppendingValidatorContext extends DelegatingValidatorContext {        private String field;        private String message;        private ValidatorContext parent;        public AppendingValidatorContext(ValidatorContext parent, Object object, String field, String message) {            super(parent, makeTextProvider(object, parent), parent);            this.field = field;            this.message = message;            this.parent = parent;        }        /**         * Translates a simple field name into a full field name in Ognl syntax         *         * @param fieldName field name in OGNL syntax         * @return field name in OGNL syntax         */        @Override        public String getFullFieldName(String fieldName) {            return field + "." + fieldName;        }        public String getFullFieldNameFromParent(String fieldName) {            return parent.getFullFieldName(field + "." + fieldName);        }        @Override        public void addActionError(String anErrorMessage) {            super.addFieldError(getFullFieldName(field), message + anErrorMessage);        }        @Override        public void addFieldError(String fieldName, String errorMessage) {            super.addFieldError(getFullFieldName(fieldName), message + errorMessage);        }    }}

可以看到有两个属性context 和 appendPrefix是可以在xml配置的，注意的是我测试后发现他们的作用和参考的文章里说的不太一样
context , 这个应该是用来按指定的context的值来区别不同的Bean验证的，默认是Action的Name（），既可以根据这个来实现对同一个Bean 进行不同的验证配置，这个可以根据具体验证的需求自由定义，对应的Bean验证Xml的名字就应该是 BeanName-context-validation.xml ，如果找不到这个，就会找 BeanName-validation.xml 。
appendPrefix ， 默认就是true , 这个是用来指定是否在返回的错误的key是否加action中被验证的那个Bean的变量名做前缀的，而不是控制是否把<message>标签中的信息加到验证信息前。

<message>标签中的信息总会被加到验证信息前的，除非是空信息，加上了也看不到。

下是我的代码：
Bean：

public class Supervisor {private String username ;private String password ;private Role role ;public void setEnable(Boolean enable) {this.enable = enable;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}}

RootAction-validation.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE validators PUBLIC"-//Apache Struts//XWork Validator 1.0.3//EN" "http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd"><validators><field name="supervisor"><field-validator type="visitor"><!--默认配置，下面两条可不写 <param name="context">userContext</param>            <param name="appendPrefix">true</param>--><message /><!--这个标签必须写--></field-validator></field></validators>

Supervisor-validation.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE validators PUBLIC"-//Apache Struts//XWork Validator 1.0.3//EN" "http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd"><validators><field name="username"><field-validator type="requiredstring"><message key="username.blank" /></field-validator><field-validator type="regex"><param name="regex"><![CDATA[^[^\d][\w]+$]]></param><message key="username.illegal"/></field-validator></field><field name="password"><field-validator type="requiredstring"><message key="password.blank" /></field-validator><field-validator type="stringlength"><param name="minLength">6</param>            <param name="maxLength">10</param>            <message key="password.illegal"/></field-validator></field></validators>

当appendPrefix为true ，debug中：

false：

还有一点要注意，就是当bean取值为null时，虽然不会执行验证了，但会出个 WARN ，提示说这个Bean 是null的，如果不想看到，可以把log的级别改一下，反正我是看到有WARN也不舒服的~