barcode EAN13 最後一位驗證碼

/**
 * 計算barcode最後一位
 * @param code 12位的barcode
 * @return
 */
public static String padBarcode(String code){
	if( null == code || code.length() != 12 ){
		throw new NullPointerException("code 的位數不對！");
	}
	//補上位數 code
	String code_ = code+"0";
	int totalEvent = 0;
	int totalCardinal = 0;
	
	char[] resolve = code_.toCharArray();
	for( int i = 1; i <= resolve.length; i++ )
	{
		int temp = Integer.parseInt((resolve[i-1])+"");
		if( i % 2 == 0 ){
			totalEvent += temp;//偶數和
		}else{
			totalCardinal += temp;//基數和
		} 
	}
	int x = ( totalEvent * 3 ) + totalCardinal;
	
	//取x的值   10最小整數倍的數
	int all = x; 
	if( x % 10 != 0 ){
		all = ( (x / 10 +1) * 10);
	}
	return code+(all-x);
}