看火龙果写了一个验证日期的Java正则表达式，就给转了过来
由于使用到了反向预搜索模式“(?<=)”和“(?<!)”，所以这个只能在 Java 中使用，不能在 JavaScript 中使用，JavaScript 不支持反向预搜索。支持 yyyy-MM-dd、yyy-MM-dd、yy-MM-dd 和 y-MM-dd，即年份为 1～4 位数字，范围（1～9999，不存在公元 0 年），月和日应为两位数字（月和日要为一位数字的话还需要稍微修改一下），分隔符为“-”（凡是分隔符的地方都加上了注释，可以改成其他的字符）。
下面是源代码：
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class DateRegex {
public static void main(String[] args) {
String[] str = {
"2001-0-0", "2001-1-1", "2001-1-30", "2001-1-31",
"2001-1-32", "2001-2-1", "2001-2-27", "2001-2-28",
"2004-2-29", "2001-2-29", "2001-2-30", "2001-2-31",
"2001-2-32", "2001-3-1", "2001-3-10", "2001-3-29",
"2001-3-30", "2001-3-31", "2001-3-32", "2001-4-1",
"2001-4-10", "2001-4-29", "2001-4-30", "2001-4-31",
"2001-4-32", "2001-5-1", "2001-5-10", "2001-5-29",
"2001-5-30", "2001-5-31", "2001-5-32", "2001-6-1",
"2001-6-10", "2001-6-29", "2001-6-30", "2001-6-31",
"2001-6-32", "2001-7-1", "2001-7-10", "2001-7-29",
"2001-7-30", "2001-7-31", "2001-7-32", "2001-8-1",
"2001-8-10", "2001-8-29", "2001-8-30", "2001-8-31",
"2001-8-32", "2001-9-1", "2001-9-10", "2001-9-29",
"2001-9-30", "2001-9-31", "2001-9-32", "2001-10-1",
"2001-10-10", "2001-10-29", "2001-10-30", "2001-10-31",
"2001-10-32", "2001-11-1", "2001-11-10", "2001-11-29",
"2001-11-30", "2001-11-31", "2001-11-32", "2001-12-1",
"2001-12-10", "2001-12-29", "2001-12-30", "2001-12-31",
"20
