for ip address and hostname

ValidIpAddressRegex = "^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$";

ValidHostnameRegex = "^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z]|[A-Za-z][A-Za-z0-9\-]*[A-Za-z0-9])$";

js a-zA-z0-9_中文 regex test

function isChn(str){

　　var reg = /^[a-zA-Z0-9_\u4e00-\u9fa5]{0,}$/;
　　if(reg.test(str)){
　　 //alert("是中文");
return true;
　　}
　 //alert("不是中文");
return false;
}

online regex testor

http://www.regexplanet.com/simple/

check valid email address in Java.

//Initialize reg ex for email.
String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
CharSequence inputStr = email;
//Make the comparison case-insensitive.
Pattern pattern = Pattern.compile(expression,Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(inputStr);
if(matcher.matches()){
isValid = true;
}
return isValid;
}

Regular expression - Wikipedia, the free encyclopedia

Regular expression - Wikipedia, the free encyclopedia