專案需要網上找了幾個工具類計算都不準確！最後發現使用Calendar計算很方便。

     public static String getAge(String date) {
    String[] data = date.split("-");
    if (data.length < 3) return "";
    Integer.valueOf(Log.d(TAG, data[0]));
    Integer.valueOf(Log.d(TAG, data[1]));
    Integer.valueOf(Log.d(TAG, data[2]));
    Calendar birthday = new GregorianCalendar(Integer.valueOf(data[0]), Integer.valueOf(data[1]), Integer.valueOf(data[2]));
    Calendar now = Calendar.getInstance();
    int day = now.get(Calendar.DAY_OF_MONTH) - birthday.get(Calendar.DAY_OF_MONTH);
    int month = now.get(Calendar.MONTH) + 1 - birthday.get(Calendar.MONTH);
    int year = now.get(Calendar.YEAR) - birthday.get(Calendar.YEAR);
    //按照減法原理，先day相減，不夠向month借；然後month相減，不夠向year借；最後year相減。  
    if (day < 0) {
        month -= 1;
        now.add(Calendar.MONTH, -1);//得到上一個月，用來得到上個月的天數。  
        day = day + now.getActualMaximum(Calendar.DAY_OF_MONTH);
    }
    if (month < 0) {
        month = (month + 12) % 12;
        year--;
    }
    System.out.println("年齡：" + year + "歲" + month + "月" + day + "天");
    StringBuffer tag = new StringBuffer();
    if (year > 0) {
        tag.append(year + "歲");
    }
    if (month > 0) {
        tag.append(month + "個月");
    }
    if (day > 0) {
        tag.append(day + "天");
    }
    if (year == 0 && month == 0 && day == 0) {
        tag.append("今日出生");
    }
    return String.valueOf(tag);
}