check.java

基于jsp技术的网上书店

package dbms;
public class check
{
	//检查输入是否为空
	public boolean isEmpty(String str)
	{
		str=str.trim();
		if(str.length()==0)
			return true;
		else return false;
	}
	//检查输入是否为整数
	public boolean isInt(String str)
	{
	        str=str.trim();
		try
		{
		Integer int_num=new Integer(0);
		int int_out=int_num.parseInt(str);
		}
		catch(NumberFormatException e)
		{return false;}
		return true;
	}
	//检查输入的范围是否正确
	public boolean isBetween(String str,int low,int high)
	{
		str=str.trim();
		Integer int_num=new Integer(0);
		int num=int_num.parseInt(str);
		if(num<=high&&num>=low)
		{
			return true;
		}
		else
		{
			return false;
		}
	}
	//检查输入的日期是否正确，并输出结果
	public boolean isDate(String stryear,String strmonth,String strday)
	{
		stryear=stryear.trim();
		strmonth=strmonth.trim();
		strday=strday.trim();
		if(isEmpty(stryear))
		{
			//String str="error! year is empty!";
			return false;
		}
		if(isEmpty(strmonth))
		{
			//String str="error! month is empty!";
			return false;
		}
		if(isEmpty(strday))
		{
			//String str="error! day is empty!";
			return false;
		}

		Integer my_int=new Integer(0);
		int year=my_int.parseInt(stryear);
		int month=my_int.parseInt(strmonth);
		int day=my_int.parseInt(strday);
		boolean haserror=false;
		String errormsg="error!";
		if(year<1800||year>2001)
		{
			haserror=true;
			errormsg+=" year must be in 1800~2001! ";
		}
		if(month>12||month<1)
		{
			haserror=true;
			errormsg+=" month must be in 1~12! ";
		}
		int maxDays=31;
		if(month==4||month==6||month==9||month==11)
		{
			maxDays=30;
		}
		else if(month==2)
		{
			if(year%4>0)
			{
				maxDays=28;
			}
			else if(year%100==0&&year%400>0)
			{
				maxDays=28;
			}
			else
			{
				maxDays=29;
			}
		}
		if(!(day>0&&day<=maxDays))
		{
			haserror=true;
			errormsg+="there isn't "+day+" days in this month! ";
		}
		if(haserror)
		{
			String str=year+"-"+month+"-"+day+"!";
			return false;
		}
		else
		{
			String str=year+"-"+month+"-"+day+"!";
			return true;
		}
	}
	//检查输入的地址是否正确，并输出结果
	public boolean isEmail(String email)
	{
		email=email.trim();
		if(isEmpty(email))
		{
			//String msg="error! Email is empty!";
			return false;
		}
		int str_pos=email.indexOf("@");
		if(str_pos==-1||email.indexOf(".",str_pos)==-1)
		{
			//String msg=" error! Email format is wrong! ";
			return false;
		}
		else
		{
			return true;
		}
	}
}