asp.net MaxLengthValidator 最大长度验证控件代码

/// <summary>
/// textbox的最大长度验证器，如果是varchar，char字段类型，需要此验证
/// </summary>
[description("对maxlength进行验证")]
[toolboxdata("<{0}:maxlengthvalidator runat=server></{0}:maxlengthvalidator>")]
public class maxlengthvalidator : basevalidator
{
/// <summary>
/// 获取或设置是否为非nvarchar,nchar字段验证
/// </summary>
[defaultvalue(true)]
public bool validatefornonnationalfield
{
get
{
var data = this.viewstate["validatefornonnationalfield"];
if (data == null)
{
return true;
}
else
{
return (bool)data;
}
}
set
{
this.viewstate["validatefornonnationalfield"] = value;
}
}

/// <summary>
/// 构造函数
/// </summary>
public maxlengthvalidator()
{
this.validatefornonnationalfield = true;
}

protected override bool evaluateisvalid()
{
var targetcontrolname = this.controltovalidate;
if (targetcontrolname == null)
{
//没有目标验证控件，验证通过
return true;
}

var targetcontrol = this.namingcontainer.findcontrol(targetcontrolname) as textbox;
if (targetcontrol == null)
{
//目标控件不是文本框或不存在，验证通过
return true;
}

var maxlength = targetcontrol.maxlength;
var targetvalue = this.getcontrolvalidationvalue(targetcontrolname);
var targetlength = 0;
if (string.isnullorempty(targetvalue))
{
targetlength = 0;
}
else
{
if (this.validatefornonnationalfield)
{
targetlength = this.getlengthfornonnationnal(targetvalue);
}
else
{
targetlength = targetvalue.length;
}
}

return targetlength <= maxlength;
}

/// <summary>
/// 获得保存为varchar时，text的长度
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
public virtual int getlengthfornonnationnal(string text)
{
if (string.isnullorempty(text))
{
return 0;
}

var length = 0;
for (var i = 0; i < text.tochararray().length; i++)
{
var charcode = (int)text[i];

length++;
if (charcode > 255)
{
length++;
}
}
return length;
}

protected override void addattributestorender(htmltextwriter writer)
{
base.addattributestorender(writer);

if (this.renderuplevel)
{
writer.addattribute("targetcontrolid",
this.getcontrolrenderid(this.controltovalidate));
writer.addattribute("validatefornonnationalfield",
this.validatefornonnationalfield ? "true" : "false");
writer.addattribute("evaluationfunction",
"maxlengthvalidator_validate");

var targetcontrol = this.namingcontainer.findcontrol(this.controltovalidate) as textbox;
if (targetcontrol != null)
{
var maxlength = targetcontrol.maxlength;
writer.addattribute("maxlength",
maxlength.tostring());
}
}
}

protected override void onprerender(eventargs e)
{
var script = @"
function maxlengthvalidator_getnonnationallength(text) {
if (!text){
return 0;
}
var length = 0;
for (var i = 0; i < text.length; i++) {
var charcode = text.charcodeat(i);
length++;
if (charcode > 255) {
length++;
}
}
return length;
}
function maxlengthvalidator_validate(val) {
if (!val) {
return true;
}
var targetid = val.targetcontrolid;
if (!targetid) {
return true;
}
var nonnational = val.validatefornonnationalfield;
if (!nonnational) {
return true;
}
var target = document.getelementbyid(targetid);
if (!target) {
return true;
}
var maxlength = val.maxlength;
if (!maxlength || isnan(maxlength)) {
return true;
}
var targetvalue = target.value;
if (!targetvalue) {
return true;
}
var reallength = targetvalue.length;
if (nonnational == 'true')
{
reallength = maxlengthvalidator_getnonnationallength(targetvalue);
}
return reallength <= parseint(maxlength);
}";
scriptmanager.registerclientscriptblock(this,
typeof(maxlengthvalidator),
"maxlengthvalidator_validate",
script,
true);

base.onprerender(e);
}
}