src/org/nutz/lang/Strings.java
public static String dup(CharSequence cs, int num) {
        if (isEmpty(cs) || num <= 0)
            return "";
        StringBuilder sb = new StringBuilder(cs.length() * num);
        for (int i = 0; i < num; i++)
            sb.append(cs);
        return sb.toString();
    }
public static String dup(CharSequence cs, int num) {
        if (isEmpty(cs) || num <= 0)
            return "";
        StringBuilder sb = new StringBuilder(cs.length() * num);
        for (int i = 0; i < num; i++)
            sb.append(cs);
        return sb.toString();
    }
复制字符串

@param cs
字符串
@param num
数量
@return 新字符串