使用星号遮挡email地址, masking email address using stars * :)

MaskUtils.java

   /**
     * 遮掩指定的位置
     * @param array
     * @param positions
     * @return
     */
    private static String mask(char[] array, int[] positions){
    	for(int position : positions){
    		array[position] = '*';
    	}
    	return new String(array);
    }
    
    /**
     * 0
     * 0*
     * 0*2
     * 0**3
     * 01**4
     * 01**45
     * 01***56
     * 01***567
     * 012***678
     * 012****789
     * 0123****890
     * >=12 位的只显示前后4位
     * 
     * 用星号遮挡邮件地址
     * @param email
     * @return
     */
    public static String maskEmail(String email){
    	if(!EmailValidator.getInstance().isValid(email)){
    		logger.warn(String.format("错误的email格式:%s", email));
    		return email;
    	}
    	int index = email.indexOf('@');
    	String prefix = email.substring(0, index);
    	String suffix = email.substring(index);
    	
    	int length = prefix.length();
    	char[] array = prefix.toCharArray();
    	String output = null;
    	switch(length){ // 虽然挺土的，但很实用... simple & stupid
	    	case 1: output = email; break;
	    	case 2: output = mask(array, new int[]{1})+suffix; break;
	    	case 3: output = mask(array, new int[]{1,2})+suffix; break;
	    	case 4: output = mask(array, new int[]{1,2})+suffix; break;
	    	case 5: output = mask(array, new int[]{2,3})+suffix; break;
	    	case 6: output = mask(array, new int[]{2,3,4})+suffix; break;
	    	case 7: output = mask(array, new int[]{2,3,4})+suffix; break;
	    	case 8: output = mask(array, new int[]{2,3,4})+suffix; break;
	    	case 9: output = mask(array, new int[]{3,4,5})+suffix; break;
	    	case 10: output = mask(array, new int[]{3,4,5,6})+suffix; break;
	    	case 11: output = mask(array, new int[]{4,5,6,7})+suffix; break;
	    	default:
	    		for(int i = 4; i < length - 4; i++){
	    			array[i] = '*';
	    		}
	    		output = new String(array)+suffix;
	    		break;
    	}
    	return output;
    }