利用strut2标签自动生成form前端验证代码，使用到的技术有
1.struts2标签，如<s:form> <s:textfieled>
2.struts2读取*Validation.xml文件（*为Action名字），
org.apache.struts2.components.Form.findFieldValidators(String name, Class actionClass, String actionName, List<Validator> validatorList, List<Validator> retultValidators, String prefix)
这是在freemarker解析form-close.ftl文件（<#assign validators=tag.getValidators("${tagName}")>）是调用的，获取关于某个输入控件的所有验证，如非空验证/长度验证
3.在void org.apache.struts2.components.UIBean.evaluateParams()方法中，会解析Form标签下的所有输入控件标签，
如<s:textfield>，<s:textarea>，主要是得到输入控件的name属性值，并存放在Map<String, Object> org.apache.struts2.components.Component.parameters这个属性中（Form.java继承与Component），
4.Freemarker解析form-close.ftl文件，主要做的工作是
遍历Map<String, Object> org.apache.struts2.components.Component.parameters字段，得到某个输入控件的tagName，
通过调用Form.findFieldValidators得到关于该输入控件的所有验证（如非空/长度/范围等）
5.解析form-close.ftl可能生成的代码如下形式，使用了jquery-validation插件：
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</form>
<script type="text/javascript">$(function() { //最大提示信息数 var maxTips = 10; // validate form on keyup and submit var formElement = $("#submitDeviceManagementAdd"); //是否正在提交 var isSubmitting = false; formElement.validate({ rules: { "device.dimensionNo":{ trim:'true', minlength:1, maxlength:20 ,customValidation: true } ,"device.assetsNo":{ trim:'true', minlength:1, maxlength:25 ,customValidation: true } ,"device.buildingName":{ required: true, minlength:0 ,customValidation: true } ,"device.brandName":{ required: true, minlength:0 , trim:'true', minlength:1, maxlength:50 ,customValidation: true } ,"device.deviceModel":{ required: true, minlength:0 , trim:'true', minlength:1, maxlength:128 ,customValidation: true } ,"device.ipv4":{ trim:'true', minlength:1, maxlength:200 ,customValidation: true } ,"device.macAddress":{ trim:'true', minlength:1, maxlength:128 ,customValidation: true } ,"device.remark":{ trim:'true', minlength:1, maxlength:2000 ,customValidation: true } }, messages: { "device.dimensionNo":{ minlength:"二维码编号的长度只能是1到20个字符！", maxlength:"二维码编号的长度只能是1到20个字符！" ,customValidation: '_customValidationMessage' } ,"device.assetsNo":{ minlength:"固定资产编号的长度只能是1到25个字符！", maxlength:"固定资产编号的长度只能是1到25个字符！" ,customValidation: '_customValidationMessage' } ,"device.buildingName":{ required: "使用单位是必填项！" ,customValidation: '_customValidationMessage' } ,"device.brandName":{ required: "品牌是必填项！" , minlength:"品牌的长度只能是1到25个字符！", maxlength:"品牌的长度只能是1到25个字符！" ,customValidation: '_customValidationMessage' } ,"device.deviceModel":{ required: "设备型号是必填项！" , minlength:"设备型号的长度只能是1到128个字符！", maxlength:"设备型号的长度只能是1到128个字符！" ,customValidation: '_customValidationMessage' } ,"device.ipv4":{ minlength:"IP地址的长度只能是1到100个字符！", maxlength:"IP地址的长度只能是1到100个字符！" ,customValidation: '_customValidationMessage' } ,"device.macAddress":{ minlength:"MAC地址的长度只能是1到128个字符！", maxlength:"MAC地址的长度只能是1到128个字符！" ,customValidation: '_customValidationMessage' } ,"device.remark":{ minlength:"备注的长度只能是1到1000个字符！", maxlength:"备注的长度只能是1到1000个字符！" ,customValidation: '_customValidationMessage' } }, errorPlacement: function(error, element) { // Set positioning based on the elements position in the form var elem = $(element); if (elem.attr('type') == 'hidden') { var widgetName = elem.attr('name') + '_widget'; elem = elem.next("input[name=" + widgetName + "]"); } // Check we have a valid error message if(!error.is(':empty')) { elem.addClass('add_error_border'); var show = elem.qtip('api') != undefined; // Apply the tooltip only if it isn't valid elem.filter(function() { if ($(this).hasClass('ui-autocomplete-input') || !$(this).hasClass('valid')) { $(this).removeClass('valid'); return true; } else return false; }).qtip({ overwrite: false, content: error, position: { my: 'left bottom', at: 'right top' }, show: { event: 'mouseenter', ready: true, persistent: false }, hide: false, style: { classes: 'ui-tooltip-red' // Make it red... the classic error colour! }, events: { show: function(event, api) { var currentTips = formElement.data('currentTips'); if (typeof currentTips == 'undefined') { currentTips = 0; } if (++currentTips <= maxTips) { formElement.data('currentTips', currentTips); _timer.call(api.elements.tooltip, event); } else { return false; } }, hide: function(event, api) { var currentTips = formElement.data('currentTips'); if (typeof currentTips != 'undefined') { if (--currentTips < 0) { currentTips = 0; } formElement.data('currentTips', currentTips); } } } }) // If we have a tooltip on this element already, just update its content .qtip('option', 'content.text', error); if (show) { elem.qtip('show'); } } // If the error is empty, remove the qTip else { if(elem.hasClass('add_error_border')){ elem.toggleClass('add_error_border'); } elem.qtip('destroy'); formElement.data('currentTips', 0); } }, success: $.noop, // Odd workaround for errorPlacement not firing! submitHandler: function(form) { if (isSubmitting) { alert("请勿重复提交表单！"); } else { isSubmitting = true; form.submit(); } }, focusInvalid: false, debug: false }); $.validator.addMethod("trim", function(value, element, params) { if (params.trim === 'true') { $(element).val($.trim($(element).val())); } return true; }); $.validator.addMethod("customValidation", function(value, element, params) { var result = true; return true; }); });</script>
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