Struts2 自定义validator 防止页面提交的list值重复

最近做小项目的时候，由于页面上有许多list，提交上来后，要将list中所有对象都保存至数据库。如果list中对象主键有重复的话，那么主键冲突就保存不了，因此对这种情况应该进行验证。

struts2的验证框架可谓是非常优雅，但无奈默认提供的validators中没有满足这种需求的validator，因此需要进行扩展。

对于扩展struts2 validator框架的介绍有很多，例如：
http://developer.51cto.com/art/201103/251944.htm
在此就不重复介绍了


首先是我们自定义的validator

package com.zyl.eduInfoStat.validator;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

import com.opensymphony.xwork2.validator.ValidationException;
import com.opensymphony.xwork2.validator.validators.FieldValidatorSupport;
import com.zyl.eduInfoStat.model.help.ListValidateAble;

public class ListRepeatValidator extends FieldValidatorSupport {

	@SuppressWarnings("unchecked")
	@Override
	public void validate(Object o) throws ValidationException {
		// TODO Auto-generated method stub
		String listName = getFieldName();
		List<ListValidateAble> list = (List<ListValidateAble>) this
				.getFieldValue(listName, o);
		Set<String> set = new HashSet<String>();
		for (ListValidateAble lva : list) {
			if (set.contains(lva.getStrForValidate())) {
				addFieldError(listName, o);
				return;
			}
			set.add(lva.getStrForValidate());
		}
	}

}

这段代码就是验证list内容重不重复的主要逻辑，非常简便，其中ListValidateAble是一个接口，所有需要这个验证器验证的对象都需要implements这个接口。这个接口定义非常简单：

package com.zyl.eduInfoStat.model.help;

public interface ListValidateAble {
	public String getStrForValidate();

}

之所以定义这个接口，是为了将自定义的ListRepeatValidator具有普适性.只要list中的对象是扩展了这个接口的，都可以用ListRepeatValidator验证。
如：

package com.zyl.eduInfoStat.model;

import java.io.Serializable;

import com.zyl.eduInfoStat.model.help.ListValidateAble;

public class EquipInfo_trainRoom implements Serializable ,ListValidateAble{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	/**
	 * 在表中的序号，用于保持显示顺序
	 */
	private int i;
	private String schoolName;
	private String roomName;
	

	public String getSchoolName() {
		return schoolName;
	}

	public void setSchoolName(String schoolName) {
		this.schoolName = schoolName;
	}

	public String getRoomName() {
		return roomName;
	}

	public void setRoomName(String roomName) {
		this.roomName = roomName;
	}

	public int getI() {
		return i;
	}

	public void setI(int i) {
		this.i = i;
	}

	@Override
	public String getStrForValidate() {
		// TODO Auto-generated method stub
		return schoolName;
	}
}

接下来是validators.xml，我们需要将这个文件放到classpath的根目录下。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
        "-//Apache Struts//XWork Validator Definition 1.0//EN"
        "http://struts.apache.org/dtds/xwork-validator-definition-1.0.dtd">

<!-- START SNIPPET: validators-default -->
<validators>
    <validator name="required" class="com.opensymphony.xwork2.validator.validators.RequiredFieldValidator"/>
    <validator name="requiredstring" class="com.opensymphony.xwork2.validator.validators.RequiredStringValidator"/>
    <validator name="int" class="com.opensymphony.xwork2.validator.validators.IntRangeFieldValidator"/>
    <validator name="long" class="com.opensymphony.xwork2.validator.validators.LongRangeFieldValidator"/>
    <validator name="short" class="com.opensymphony.xwork2.validator.validators.ShortRangeFieldValidator"/>
    <validator name="double" class="com.opensymphony.xwork2.validator.validators.DoubleRangeFieldValidator"/>
    <validator name="date" class="com.opensymphony.xwork2.validator.validators.DateRangeFieldValidator"/>
    <validator name="expression" class="com.opensymphony.xwork2.validator.validators.ExpressionValidator"/>
    <validator name="fieldexpression" class="com.opensymphony.xwork2.validator.validators.FieldExpressionValidator"/>
    <validator name="email" class="com.opensymphony.xwork2.validator.validators.EmailValidator"/>
    <validator name="url" class="com.opensymphony.xwork2.validator.validators.URLValidator"/>
    <validator name="visitor" class="com.opensymphony.xwork2.validator.validators.VisitorFieldValidator"/>
    <validator name="conversion" class="com.opensymphony.xwork2.validator.validators.ConversionErrorFieldValidator"/>
    <validator name="stringlength" class="com.opensymphony.xwork2.validator.validators.StringLengthFieldValidator"/>
    <validator name="regex" class="com.opensymphony.xwork2.validator.validators.RegexFieldValidator"/>
    <validator name="conditionalvisitor" class="com.opensymphony.xwork2.validator.validators.ConditionalVisitorFieldValidator"/>
    
    
    <!-- 自定义的验证器 -->
     <validator name="listRepeat" class="com.zyl.eduInfoStat.validator.ListRepeatValidator"/>
</validators>
<!--  END SNIPPET: validators-default -->

我们自定义的ListRepeatValidator在最下方，上方是系统默认提供的验证器。

最后是action的配置,如EquipInfoSubmitAction-validation.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator 1.0.2//EN" "http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd">
<validators >     
    <field name="equipInfo_trainRoom_list">
    	<field-validator type ="listRepeat" > 
            <message>值不能重复！</message>   
        </field-validator > 
    </field>
</validators>   

如此便大功告成了！


PS.
写代码一有问题，便是上网搜，解决了无数的问题。想着咱也必须贡献一点力啊~