Java实现身份证校验算法

public class ValidateNumberId {
	
	private static String[]  validtable =  {"1","0","X","9","8","7","6","5","4","3","2"};
	
	public static boolean cleckIdNumber(String ID){
		boolean flag = false;
		//验证码
		String validatecode = ID.substring(17,18);
		//前17位称为本体码
		String selfcode = ID.substring(0,17);
		String code[]=new String[17];
		for(int i=0;i<17;i++){
			code[i] = selfcode.substring(i,i+1);
		}
		//加权因子公式：2的n-1次幂除以11取余数，n就是那个i，从右向左排列。
		int sum = 0;   //用于加权数求和
		for(int i=0;i<code.length;i++){
			//计算该位加权因子
			int yi = adjustmentfactor(i+1)%11;
			//得到对应数位上的数字
			int count = Integer.parseInt(code[code.length-i-1]);
			//加权求和 
			sum +=(count*yi);
		}
	    //验证校验码是否正确
		String valdate = validtable[sum%11];
		if(valdate.equalsIgnoreCase(validatecode)) {
			flag = true;
		}
		return flag;
	}
	/**
	* 计算身份证数位数字加权因子
	* digit表示数位
	*/
	public static int adjustmentfactor(int digit){
		int sum = 1;
		for(int i=0;i<digit;i++){
		    //sum=sum*2;
			sum=sum<<1;
		}
		return sum;
	}
	
	public static void main(String[] args) {
		System.out.println(System.currentTimeMillis());
		System.out.println(cleckIdNumber("身份证号码"));
		System.out.println(System.currentTimeMillis());
	}
}