jsp中如何判断 字符串是否为日期?谢大家

Question

如"P20010101ts"这种就不是日期,"20050101"说是日期.这个如何判断?

Answer 1

可以用structs的validate验证框架，如果没用也可以参考他生成的javascript脚本

Answer 2

/*$RCSfile: validateDate.js,v $ $Revision: 1.10 $ $Date: 2004/03/28 16:53:21 $ */
    /**
    * Check to see if fields are a valid date.
    * Fields are not checked if they are disabled.
    * <p>
    * @param form The form validation is taking place on.
    */
    function validateDate(form) {
       var bValid = true;
       var focusField = null;
       var i = 0;
       var fields = new Array();
       var formName = form.getAttributeNode("name");        oDate = eval('new ' + formName.value + '_DateValidations()');       for (x in oDate) {
           var field = form[oDate[x][0]];
   if(field==null) continue;
           var value = field.value;
           var datePattern = oDate[x][2]("datePatternStrict");
           // try loose pattern
           if (datePattern == null)
               datePattern = oDate[x][2]("datePattern");
           if ((field.type == 'hidden' ||
                field.type == 'text' ||
                field.type == 'textarea') &&
               (value.length > 0) && (datePattern.length > 0) &&
                field.disabled == false) {
                 var MONTH = "MM";
                 var DAY = "dd";
                 var YEAR = "yyyy";
                 var orderMonth = datePattern.indexOf(MONTH);
                 var orderDay = datePattern.indexOf(DAY);
                 var orderYear = datePattern.indexOf(YEAR);
                 if ((orderDay < orderYear && orderDay > orderMonth)) {
                     var iDelim1 = orderMonth + MONTH.length;
                     var iDelim2 = orderDay + DAY.length;
                     var delim1 = datePattern.substring(iDelim1, iDelim1 + 1);
                     var delim2 = datePattern.substring(iDelim2, iDelim2 + 1);
                     if (iDelim1 == orderDay && iDelim2 == orderYear) {
                        dateRegexp = new RegExp("^(\\d{2})(\\d{2})(\\d{4})$");
                     } else if (iDelim1 == orderDay) {
                        dateRegexp = new RegExp("^(\\d{2})(\\d{2})[" + delim2 + "](\\d{4})$");
                     } else if (iDelim2 == orderYear) {
                        dateRegexp = new RegExp("^(\\d{2})[" + delim1 + "](\\d{2})(\\d{4})$");
                     } else {
                        dateRegexp = new RegExp("^(\\d{2})[" + delim1 + "](\\d{2})[" + delim2 + "](\\d{4})$");
                     }
                     var matched = dateRegexp.exec(value);
                     if(matched != null) {
                        if (!isValidDate(matched[2], matched[1], matched[3])) {
                           if (i == 0) {
                               focusField = field;
                           }
                           fields[i++] = oDate[x][1];
                           bValid =  false;
                        }
                     } else {
                        if (i == 0) {
                            focusField = field;
                        }
                        fields[i++] = oDate[x][1];
                        bValid =  false;
                     }
                 } else if ((orderMonth < orderYear && orderMonth > orderDay)) {
                     var iDelim1 = orderDay + DAY.length;
                     var iDelim2 = orderMonth + MONTH.length;
                     var delim1 = datePattern.substring(iDelim1, iDelim1 + 1);
                     var delim2 = datePattern.substring(iDelim2, iDelim2 + 1);
                     if (iDelim1 == orderMonth && iDelim2 == orderYear) {
                         dateRegexp = new RegExp("^(\\d{2})(\\d{2})(\\d{4})$");
                     } else if (iDelim1 == orderMonth) {
                         dateRegexp = new RegExp("^(\\d{2})(\\d{2})[" + delim2 + "](\\d{4})$");
                     } else if (iDelim2 == orderYear) {
                         dateRegexp = new RegExp("^(\\d{2})[" + delim1 + "](\\d{2})(\\d{4})$");
                     } else {
                         dateRegexp = new RegExp("^(\\d{2})[" + delim1 + "](\\d{2})[" + delim2 + "](\\d{4})$");
                     }
                     var matched = dateRegexp.exec(value);
                     if(matched != null) {
                         if (!isValidDate(matched[1], matched[2], matched[3])) {
                             if (i == 0) {
                         focusField = field;
                             }
                             fields[i++] = oDate[x][1];
                             bValid =  false;
                          }
                     } else {
                         if (i == 0) {
                             focusField = field;
                         }
                         fields[i++] = oDate[x][1];
                         bValid =  false;
                     }
                 } else if ((orderMonth > orderYear && orderMonth < orderDay)) {
                     var iDelim1 = orderYear + YEAR.length;
                     var iDelim2 = orderMonth + MONTH.length;
                     var delim1 = datePattern.substring(iDelim1, iDelim1 + 1);
                     var delim2 = datePattern.substring(iDelim2, iDelim2 + 1);
                     if (iDelim1 == orderMonth && iDelim2 == orderDay) {
                         dateRegexp = new RegExp("^(\\d{4})(\\d{2})(\\d{2})$");
                     } else if (iDelim1 == orderMonth) {
                         dateRegexp = new RegExp("^(\\d{4})(\\d{2})[" + delim2 + "](\\d{2})$");
                     } else if (iDelim2 == orderDay) {
                         dateRegexp = new RegExp("^(\\d{4})[" + delim1 + "](\\d{2})(\\d{2})$");
                     } else {
                         dateRegexp = new RegExp("^(\\d{4})[" + delim1 + "](\\d{2})[" + delim2 + "](\\d{2})$");
                     }
                     var matched = dateRegexp.exec(value);
                     if(matched != null) {
                         if (!isValidDate(matched[3], matched[2], matched[1])) {
                             if (i == 0) {
                                 focusField = field;
                             }
                             fields[i++] = oDate[x][1];
                             bValid =  false;
                         }
                     } else {
                          if (i == 0) {
                              focusField = field;
                          }
                          fields[i++] = oDate[x][1];
                          bValid =  false;
                     }
                 } else {
                     if (i == 0) {
                         focusField = field;
                     }
                     fields[i++] = oDate[x][1];
                     bValid =  false;
                 }
          }
       }
       if (fields.length > 0) {
          focusField.focus();
          alert(fields.join('\n'));
       }
       return bValid;
    }
    
    function isValidDate(day, month, year) {
    if (month < 1 || month > 12) {
            return false;
        }
        if (day < 1 || day > 31) {
            return false;
        }
        if ((month == 4 || month == 6 || month == 9 || month == 11) &&
            (day == 31)) {
            return false;
        }
        if (month == 2) {
            var leap = (year % 4 == 0 &&
               (year % 100 != 0 || year % 400 == 0));
            if (day>29 || (day == 29 && !leap)) {
                return false;
            }
        }
        return true;
    }这是从我的页面考过来的，还是第一次看呢，写的挺全面的。

Answer 3

tcl_wj(美女王&提踢题) 给的恐怕不是在Java中的实现吧，如果我没看错的话，应该是在VB中的实现，不过楼主也可以参考一下其思想。

Answer 4

如果不要求太精确，用正则表达式来解决楼主的问题最合适不过了。
不管是jsp中的java代码，还是jsp中的javascript代码，都支持正则表达式。按楼主的意思，楼主要求区分出8个数字组成的字符串，判断它是不是能代表一个合法的日期。
日期分成年月日：yyyyMMdd，
yyyy可以放宽一点，0000--9999，主要是MM，应该是01--12的，dd还是比较复杂的，与yyyy和MM有关，可能是01--28或者01--29，或者01--30，或者01--31。
要求精确的话，恐怕不好写正则表达式。如果要求很精确，那么有一个偷懒的方法，也是绝对简单，就是用java的SimpleDateFormat，先按 yyyyMMdd 解析成 java.util.Date 然后再用 SimpleDateFormat 按 yyyyMMdd 格式化它(那个Date对象)，看看得到的字符串与输入的是否一样？一样就对了，不一样就错了，呵呵！

Answer 5

如获得完整的时间格式
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;
随便介绍几个其它函数的用法：
本月的天数
SELECT to_char(last_day(SYSDATE),'dd') days FROM dual
今年的天数
select add_months(trunc(sysdate,'year'), 12) - trunc(sysdate,'year') from dual
下个星期一的日期
SELECT Next_day(SYSDATE,'monday') FROM dual

Answer 6

回复人： peacedog() ( ) 信誉：100  2005-12-8 12:02:59  得分: 0  
 
    tcl_wj(美女王&提踢题) 给的恐怕不是在Java中的实现吧，如果我没看错的话，应该是在VB中的实现，不过楼主也可以参考一下其思想。    人家不是说了么,javascript啊.程序得注释里也有.