package com.hongyuan.test;
 
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
 
public class DateUtil {
 
    //按照给定的格式化字符串格式化日期
    public static String formatDate(Date date, String formatStr) {
        SimpleDateFormat sdf = new SimpleDateFormat(formatStr);
        return sdf.format(date);
    }
 
    //按照给定的格式化字符串解析日期
    public static Date parseDate(String dateStr, String formatStr) throws ParseException {
        Date date = null;
        SimpleDateFormat sdf = new SimpleDateFormat(formatStr);
        date = sdf.parse(dateStr);
        return date;
    }
 
    //从字符串中分析日期
    public static Date parseDate(String dateStr) throws ParseException {
        Date date=null;
        String[] dateArray = dateStr.split("\\D+");     //+防止多个非数字字符在一起时导致解析错误
        int dateLen = dateArray.length;
        int dateStrLen=dateStr.length();
        if(dateLen>0){
            if(dateLen==1&&dateStrLen>4){
                if(dateStrLen=="yyyyMMddHHmmss".length()){
                    //如果字符串长度为14位并且不包含其他非数字字符，则按照（yyyyMMddHHmmss）格式解析
                    date=parseDate(dateStr,"yyyyMMddHHmmss");
                }else if(dateStrLen=="yyyyMMddHHmm".length()){
                    date=parseDate(dateStr,"yyyyMMddHHmm");
                }else if(dateStrLen=="yyyyMMddHH".length()){
                    date=parseDate(dateStr,"yyyyMMddHH");
                }else if(dateStrLen=="yyyyMMdd".length()){
                    date=parseDate(dateStr,"yyyyMMdd");
                }else if(dateStrLen=="yyyyMM".length()){
                    date=parseDate(dateStr,"yyyyMM");
                }
            }else{
                String fDateStr=dateArray[0];
                for(int i=1;i<dateLen;i++){
                    //左补齐是防止十位数省略的情况
                    fDateStr+=leftPad(dateArray[i],"0",2);
                }
                 
                if(dateStr.trim().matches("^\\d{1,2}:\\d{1,2}(:\\d{1,2})?$")){
                    //补充年月日3个字段
                    dateLen+=3;
                    fDateStr=formatDate(new Date(),"yyyyMMdd")+fDateStr;
                }
                 
                date=parseDate(fDateStr,"yyyyMMddHHmmss".substring(0, (dateLen-1)*2+4));
            }
        }
         
        return date;
    }
 
    //左补齐
    public static String leftPad(String str,String pad,int len){
        String newStr=(str==null?"":str);
        while(newStr.length()<len){
            newStr=pad+newStr;
        }
        if(newStr.length()>len){
            newStr=newStr.substring(newStr.length()-len);
        }
        return newStr;
    }
     
    public static void main(String[] args) throws ParseException {
 
        String[] dateStrArray=new String[]{
                "2014-03-12 12:05:34",
                "2014-03-12 12:05",
                "2014-03-12 12",
                "2014-03-12",
                "2014-03",
                "2014",
                "20140312120534",
                "2014/03/12 12:05:34",
                "2014/3/12 12:5:34",
                "2014年3月12日 12时5分34秒",
                "201403121205",
                "2014031212",
                "20140312",
                "201403",
                "12:05:34",
                "12:05",
        };
        for(int i=0;i<dateStrArray.length;i++){
            Date date=parseDate(dateStrArray[i]);
            System.out.println(dateStrArray[i]+" ==> "+formatDate(date,"yyyy-MM-dd HH:mm:ss"));
        }
    }
}