这段时间在做Quartz任务调度，使用的Crontab表达式实现的。Crontab由前端页面输入，作为参数穿入后台。
虽然Quartz具有校验Crontab表达式的方法，如下：

boolean cronExpressionFlag = CronExpression.isValidExpression(crontab);

但是我一直想在前端直接验证，即不需要通过异步的方式向后台获取验证结果，找了好久，发现没有现成的框架可以使用，于是自己根据网上搜索到的资料，写了这个js脚本。
这个脚本目前对日和星期的判断还有点小问题，不过不影响使用。
以后如果有时间，继续完善这个脚本，废话不多说了，上代码：

    function cronValidate() {var cron = $("#cron").val();var result = CronExpressionValidator.validateCronExpression(cron);if(result == true){alert("格式正确");  }else{alert("格式错误");}return CronExpressionValidator.validateCronExpression(cron);  } function CronExpressionValidator() {  }  CronExpressionValidator.validateCronExpression = function(value) {  var results = true;  if (value == null || value.length == 0) {  return false;  }  // split and test length  var expressionArray = value.split(" ");  var len = expressionArray.length;  if ((len != 6) && (len != 7)) {  return false;  }  // check only one question mark  var match = value.match(/\?/g);  if (match != null && match.length > 1) {  return false;  }  // check only one question mark  var dayOfTheMonthWildcard = "";  // if appropriate length test parts  // [0] Seconds 0-59 , - * /  if (CronExpressionValidator.isNotWildCard(expressionArray[0], /[\*]/gi)) {  if (!CronExpressionValidator.segmentValidator("([0-9\\\\,-\\/])", expressionArray[0], [0, 59], "seconds")) {  return false;  }  }  // [1] Minutes 0-59 , - * /  if (CronExpressionValidator.isNotWildCard(expressionArray[1], /[\*]/gi)) {  if (!CronExpressionValidator.segmentValidator("([0-9\\\\,-\\/])", expressionArray[1], [0, 59], "minutes")) {  return false;  }  }  // [2] Hours 0-23 , - * /  if (CronExpressionValidator.isNotWildCard(expressionArray[2], /[\*]/gi)) {  if (!CronExpressionValidator.segmentValidator("([0-9\\\\,-\\/])", expressionArray[2], [0, 23], "hours")) {  return false;  }  }  // [3] Day of month 1-31 , - * ? / L W C  if (CronExpressionValidator.isNotWildCard(expressionArray[3], /[\*\?]/gi)) {  if (!CronExpressionValidator.segmentValidator("([0-9LWC\\\\,-\\/])", expressionArray[3], [1, 31], "days of the month")) {  return false;  }  } else {  dayOfTheMonthWildcard = expressionArray[3];  }  // [4] Month 1-12 or JAN-DEC , - * /  if (CronExpressionValidator.isNotWildCard(expressionArray[4], /[\*]/gi)) {  expressionArray[4] = CronExpressionValidator.convertMonthsToInteger(expressionArray[4]);  if (!CronExpressionValidator.segmentValidator("([0-9\\\\,-\\/])", expressionArray[4], [1, 12], "months")) {  return false;  }  }  // [5] Day of week 1-7 or SUN-SAT , - * ? / L C #  if (CronExpressionValidator.isNotWildCard(expressionArray[5], /[\*\?]/gi)) {  expressionArray[5] = CronExpressionValidator.convertDaysToInteger(expressionArray[5]);  if (!CronExpressionValidator.segmentValidator("([0-9LC#\\\\,-\\/])", expressionArray[5], [1, 7], "days of the week")) {  return false;  }  } else {  if (dayOfTheMonthWildcard == String(expressionArray[5])) {  return false;  }  }  // [6] Year empty or 1970-2099 , - * /  if (len == 7) {  if (CronExpressionValidator.isNotWildCard(expressionArray[6], /[\*]/gi)) {  if (!CronExpressionValidator.segmentValidator("([0-9\\\\,-\\/])", expressionArray[6], [1970, 2099], "years")) {  return false;  }  }  }  return true;  }  // ----------------------------------  // isNotWildcard 静态方法;  // ----------------------------------  CronExpressionValidator.isNotWildCard = function(value, expression) {  var match = value.match(expression);  return (match == null || match.length == 0) ? true : false;  }  // ----------------------------------  // convertDaysToInteger 静态方法;  // ----------------------------------  CronExpressionValidator.convertDaysToInteger = function(value) {  var v = value;  v = v.replace(/SUN/gi, "1");  v = v.replace(/MON/gi, "2");  v = v.replace(/TUE/gi, "3");  v = v.replace(/WED/gi, "4");  v = v.replace(/THU/gi, "5");  v = v.replace(/FRI/gi, "6");  v = v.replace(/SAT/gi, "7");  return v;  }  // ----------------------------------  // convertMonthsToInteger 静态方法;  // ----------------------------------  CronExpressionValidator.convertMonthsToInteger = function(value) {  var v = value;  v = v.replace(/JAN/gi, "1");  v = v.replace(/FEB/gi, "2");  v = v.replace(/MAR/gi, "3");  v = v.replace(/APR/gi, "4");  v = v.replace(/MAY/gi, "5");  v = v.replace(/JUN/gi, "6");  v = v.replace(/JUL/gi, "7");  v = v.replace(/AUG/gi, "8");  v = v.replace(/SEP/gi, "9");  v = v.replace(/OCT/gi, "10");  v = v.replace(/NOV/gi, "11");  v = v.replace(/DEC/gi, "12");  return v;  }  // ----------------------------------  // segmentValidator 静态方法;  // ----------------------------------  CronExpressionValidator.segmentValidator = function(expression, value, range, segmentName) {  var v = value;  var numbers = new Array();  // first, check for any improper segments  var reg = new RegExp(expression, "gi");  if (!reg.test(v)) {   return false;  }  // check duplicate types  // check only one L  var dupMatch = value.match(/L/gi);  if (dupMatch != null && dupMatch.length > 1) {  return false;  }  // look through the segments  // break up segments on ','  // check for special cases L,W,C,/,#,-  var split = v.split(",");  var i = -1;  var l = split.length;  var match;  while (++i < l) {  // set vars  var checkSegment = split[i];  var n;  var pattern = /(\w*)/;  match = pattern.exec(checkSegment);  // if just number  pattern = /(\w*)\-?\d+(\w*)/;  match = pattern.exec(checkSegment);  if (match  && match[0] == checkSegment  && checkSegment.indexOf("L") == -1  && checkSegment.indexOf("l") == -1  && checkSegment.indexOf("C") == -1  && checkSegment.indexOf("c") == -1  && checkSegment.indexOf("W") == -1  && checkSegment.indexOf("w") == -1  && checkSegment.indexOf("/") == -1  && (checkSegment.indexOf("-") == -1 || checkSegment  .indexOf("-") == 0) && checkSegment.indexOf("#") == -1) {  n = match[0];  if (n && !(isNaN(n)))  numbers.push(n);  else if (match[0] == "0")  numbers.push(n);  continue;  }  // includes L, C, or w  pattern = /(\w*)L|C|W(\w*)/i;  match = pattern.exec(checkSegment);  if (match  && match[0] != ""  && (checkSegment.indexOf("L") > -1  || checkSegment.indexOf("l") > -1  || checkSegment.indexOf("C") > -1  || checkSegment.indexOf("c") > -1  || checkSegment.indexOf("W") > -1 || checkSegment  .indexOf("w") > -1)) {  // check just l or L  if (checkSegment == "L" || checkSegment == "l")  continue;  pattern = /(\w*)\d+(l|c|w)?(\w*)/i;  match = pattern.exec(checkSegment);  // if something before or after  if (!match || match[0] != checkSegment) {   continue;  }  // get the number  var numCheck = match[0];  numCheck = numCheck.replace(/(l|c|w)/ig, "");  n = Number(numCheck);  if (n && !(isNaN(n)))  numbers.push(n);  else if (match[0] == "0")  numbers.push(n);  continue;  }  var numberSplit;  // includes /  if (checkSegment.indexOf("/") > -1) {  // take first #  numberSplit = checkSegment.split("/");  if (numberSplit.length != 2) {   continue;  } else {  n = numberSplit[0];  if (n && !(isNaN(n)))  numbers.push(n);  else if (numberSplit[0] == "0")  numbers.push(n);  continue;  }  }  // includes #  if (checkSegment.indexOf("#") > -1) {  // take first #  numberSplit = checkSegment.split("#");  if (numberSplit.length != 2) {    continue;  } else {  n = numberSplit[0];  if (n && !(isNaN(n)))  numbers.push(n);  else if (numberSplit[0] == "0")  numbers.push(n);  continue; } }  // includes -  if (checkSegment.indexOf("-") > 0) {  // take both #  numberSplit = checkSegment.split("-");  if (numberSplit.length != 2) {   continue;  } else if (Number(numberSplit[0]) > Number(numberSplit[1])) {  continue;  } else {  n = numberSplit[0];  if (n && !(isNaN(n)))  numbers.push(n);  else if (numberSplit[0] == "0")  numbers.push(n);  n = numberSplit[1];  if (n && !(isNaN(n)))  numbers.push(n);  else if (numberSplit[1] == "0")  numbers.push(n);  continue;  }  }  }  // lastly, check that all the found numbers are in range  i = -1;  l = numbers.length;  if (l == 0)  return false;  while (++i < l) {  // alert(numbers[i]);  if (numbers[i] < range[0] || numbers[i] > range[1]) {  return false;  }  }  return true;  }