一个健壮的WEB应用程序必须确保用户的输入是合法有效的；Struts2即提供了一些基于XWork Validation Framework的内建验证程序，使得输入验证不需要编程，直接在xml配置文件中声明（待验证字段、验证规则、验证出错消息）即可。 Struts2提供声明式验证和编程式验证两种方式，常采用声明式验证程序，其主要需要声明如下内容：
对哪个Action类或Model类对象的哪个字段进行验证；采用哪种验证规则进行验证；若验证失败，则转向何处、显示什么错误信息。声明式验证程序分为字段验证和非字段验证两类，字段验证主要判断某字段属性的输入是否有效，而非字段验证主要是针对多个字段输入值之间的逻辑关系进行校验，如密码再次输入确认。
（1）基于字段的声明式验证程序的具体实现步骤
确定验证字段：确定哪个Action类或Model类对象的哪个字段需要验证；编写验证程序配置文件：若一个Action类的多个action请求使用相同的验证规则，则其文件名为ActionClassName-validation.xml，而不同则为ActionClassName-User_create-validation.xml确定验证失败时的响应页面：在struts.xml文件中定义<result name=“input”> 元素，用于指定转向页面。（2）编写验证程序配置文件
将struts-2.3.15.3/apps/struts2-blank/WEB-INF/classes/example下的Login-validation.xml文件复制到当前Action类文件所在路径下；修改配置文件名为ActionClassName-validation.xml；编写验证规则: 参见struts-2.3.15.3/docs/WW/docs/validation.html文档即可。<!--验证程序配置文件核心内容：--><field name="age"> <field-validator type="int"> <param name="min">20</param> <param name="max">50</param> <!--注意：验证程序错误消息可以进行国际化--> <message>Age needs to be between ${min} and ${max}.</message> </field-validator></field>（3）显示验证程序错误消息
<!-- 非simple主题自动显示错误消息 --><s:form action="testValidation"> <s:textfield name="age" label="Age"></s:textfield> <s:submit></s:submit></s:form><br><hr><br><!-- simple主题需要使用s:fielderror标签或EL货OGNL表达式来显示错误消息 --><s:form action="testValidation2" theme="simple"> Age: <s:textfield name="age" label="Age"></s:textfield> <br> ${fieldErrors.age[0] } <br> <s:fielderror name="age"></s:fielderror> <s:submit></s:submit></s:form>
注意：若类型转换失败，默认情况下仍会执行后续的输入验证拦截器。可通过修改ConversionErrorInterceptor源代码的方式使 类型转换失败时，直接返回input的result，即不再执行后续的验证拦截器。
// 创建相同的包 -> 新建相同的类 -> 复制源代码 -> 修改即可Object action = invocation.getAction(); if (action instanceof ValidationAware) { ValidationAware va = (ValidationAware) action; if(va.hasFieldErrors() || va.hasActionErrors()) { return "input"; } } 非字段验证不是针对单一字段的验证，可以通过<s:actionerror/>标签显示错误消息；非字段验证的配置实例如下：
问题：多个字段使用同样的验证规则，可否使用同一条验证消息 ？ 解决：利用国际化资源配置文件和fieldName特殊属性结合来实现，英文资源文件内容如下所示：
error.int=${getText(fieldName)} needs to be between ${min} and ${max}age=Agecount=Count具体代码见附录所示。
Struts2提供Validateable接口，可以使Action类实现该接口以提供编程验证功能，常选择继承于实现了Validateable 接口的ActionSupport 类。
@Overridepublic void validate() { if(name == null || name.trim().equals("")) { addFieldError("name", getText("name.null")); }}
IDCard.java：
package com.qiaobc.struts.action;public class IDCard { final int[] wi = { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2, 1 }; final int[] vi = { 1, 0, 'X', 9, 8, 7, 6, 5, 4, 3, 2 }; private int[] ai = new int[18]; public IDCard() {} public boolean Verify(String idcard) { if (idcard.length() == 15) { idcard = uptoeighteen(idcard); } if (idcard.length() != 18) { return false; } String verify = idcard.substring(17, 18); if (verify.equals(getVerify(idcard))) { return true; } return false; } public String getVerify(String eightcardid) { int remaining = 0; if (eightcardid.length() == 18) { eightcardid = eightcardid.substring(0, 17); } if (eightcardid.length() == 17) { int sum = 0; for (int i = 0; i < 17; i++) { String k = eightcardid.substring(i, i + 1); ai[i] = Integer.parseInt(k); } for (int i = 0; i < 17; i++) { sum = sum + wi[i] * ai[i]; } remaining = sum % 11; } return remaining == 2 ? "X" : String.valueOf(vi[remaining]); } public String uptoeighteen(String fifteencardid) { String eightcardid = fifteencardid.substring(0, 6); eightcardid = eightcardid + "19"; eightcardid = eightcardid + fifteencardid.substring(6, 15); eightcardid = eightcardid + getVerify(eightcardid); return eightcardid; } public static void main(String[] args) { String idcard1 = "350211197607142059"; String idcard2 = "350211197607442059"; IDCard idcard = new IDCard(); System.out.println(idcard.Verify(idcard1)); System.out.println(idcard.Verify(idcard2)); }}IDCardValidator.java：
package com.qiaobc.struts.action;import com.opensymphony.xwork2.validator.ValidationException;import com.opensymphony.xwork2.validator.validators.FieldValidatorSupport;public class IDCardValidator extends FieldValidatorSupport { @Override public void validate(Object object) throws ValidationException { // 1. 获取字段名和字段值 String fieldName = getFieldName(); Object value = this.getFieldValue(fieldName, object); // 2. 验证 IDCard idCard = new IDCard(); boolean result = idCard.Verify((String) value); // 3. 验证失败转向 if(!result) { addFieldError(fieldName, object); } }}TestValidationAction.java：
package com.qiaobc.struts.action;import com.opensymphony.xwork2.ActionSupport;public class TestValidationAction extends ActionSupport { private static final long serialVersionUID = 1L; private Integer age; private String password1; private String password2; private String idcard; public String getPassword1() { return password1; } public String getIdcard() { return idcard; } public void setIdcard(String idcard) { this.idcard = idcard; } public void setPassword1(String password1) { this.password1 = password1; } public String getPassword2() { return password2; } public void setPassword2(String password2) { this.password2 = password2; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } @Override public String execute() throws Exception { System.out.println("age:" + age); System.out.println("password1:" + password1); System.out.println("password2:" + password2); return SUCCESS; }}TestValidationAction-testValidation-validation.xml：
<!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="age"> <field-validator type="int"> <param name="min">20</param> <param name="max">50</param> <message>Age needs to be between ${min} and ${max}.</message> </field-validator> <field-validator type="conversion"> <message>Conversion Error Occurred.</message> </field-validator> </field> <field name="idcard"> <field-validator type="idcard"> <message>It's not a ID Card!</message> </field-validator> </field> <validator type="expression"> <param name="expression"><![CDATA[password1==password2]]></param> <message>password1 != password2</message> </validator></validators>TestValidationAction-testValidation2-validation.xml：
<!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="age"> <!-- 设置短路验证：若当前验证没有通过，则不再进行下面的验证 --> <field-validator type="conversion" short-circuit="true"> <message>Conversion Error Occurred.</message> </field-validator> <field-validator type="int"> <param name="min">0</param> <param name="max">100</param> <message>Age needs to be between ${min} and ${max}.</message> </field-validator> </field></validators>struts.xml：
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" "http://struts.apache.org/dtds/struts-2.3.dtd"><struts> <!-- 配置全局范围内的国际化资源文件 --> <constant name="struts.custom.i18n.resources" value="i18n"></constant> <package name="validation" namespace="/" extends="struts-default"> <action name="testValidation" class="com.qiaobc.struts.action.TestValidationAction"> <result>/success.jsp</result> <!-- 配置输入验证失败时的转向页面 --> <result name="input">/validation.jsp</result> </action> <action name="testValidation2" class="com.qiaobc.struts.action.TestValidationAction"> <result>/success.jsp</result> <!-- 配置输入验证失败时的转向页面 --> <result name="input">/validation.jsp</result> </action> </package></struts>validators.xml：
<?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"><validators> <!-- 配置自定义拦截器 --> <validator name="idcard" class="com.qiaobc.struts.action.IDCardValidator"/></validators>validation.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib uri="/struts-tags" prefix="s" %><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body> <s:debug></s:debug> <!-- 非simple主题自动显示错误消息 --> <s:form action="testValidation"> <s:textfield name="age" label="Age"></s:textfield> <s:password name="password1" label="password1"></s:password> <s:password name="password2" label="password2"></s:password> <s:actionerror/> <s:textfield name="idcard" label="IDCard"></s:textfield> <s:submit></s:submit> </s:form></body></html>validation2.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib uri="/struts-tags" prefix="s" %><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body> <s:debug></s:debug> <!-- simple主题需要使用s:fielderror标签或EL货OGNL表达式来显示错误消息 --> <s:form action="testValidation2" theme="simple"> Age: <s:textfield name="age" label="Age"></s:textfield> <br><br> <s:fielderror name="age"></s:fielderror> <s:submit></s:submit> </s:form></body></html>ConversionErrorInterceptor.java：
package com.opensymphony.xwork2.interceptor;import com.opensymphony.xwork2.ActionContext;import com.opensymphony.xwork2.ActionInvocation;import com.opensymphony.xwork2.ValidationAware;import com.opensymphony.xwork2.conversion.impl.XWorkConverter;import com.opensymphony.xwork2.util.ValueStack;import org.apache.commons.lang3.StringEscapeUtils;import java.util.HashMap;import java.util.Map;public class ConversionErrorInterceptor extends AbstractInterceptor { public static final String ORIGINAL_PROPERTY_OVERRIDE = "original.property.override"; protected Object getOverrideExpr(ActionInvocation invocation, Object value) { return escape(value); } protected String escape(Object value) { return "/"" + StringEscapeUtils.escapeJava(String.valueOf(value)) + "/""; } @Override public String intercept(ActionInvocation invocation) throws Exception { ActionContext invocationContext = invocation.getInvocationContext(); Map<String, Object> conversionErrors = invocationContext.getConversionErrors(); ValueStack stack = invocationContext.getValueStack(); HashMap<Object, Object> fakie = null; for (Map.Entry<String, Object> entry : conversionErrors.entrySet()) { String propertyName = entry.getKey(); Object value = entry.getValue(); if (shouldAddError(propertyName, value)) { String message = XWorkConverter.getConversionErrorMessage(propertyName, stack); Object action = invocation.getAction(); if (action instanceof ValidationAware) { ValidationAware va = (ValidationAware) action; va.addFieldError(propertyName, message); } if (fakie == null) { fakie = new HashMap<Object, Object>(); } fakie.put(propertyName, getOverrideExpr(invocation, value)); } } if (fakie != null) { // if there were some errors, put the original (fake) values in place right before the result stack.getContext().put(ORIGINAL_PROPERTY_OVERRIDE, fakie); invocation.addPreResultListener(new PreResultListener() { public void beforeResult(ActionInvocation invocation, String resultCode) { Map<Object, Object> fakie = (Map<Object, Object>) invocation.getInvocationContext().get(ORIGINAL_PROPERTY_OVERRIDE); if (fakie != null) { invocation.getStack().setExprOverrides(fakie); } } }); } // 核心代码 Object action = invocation.getAction(); if (action instanceof ValidationAware) { ValidationAware va = (ValidationAware) action; if(va.hasFieldErrors() || va.hasActionErrors()) { return "input"; } } return invocation.invoke(); } protected boolean shouldAddError(String propertyName, Object value) { return true; }}新闻热点
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