Java实现按长度分割字符串

有时候需要将字符串进行定长分段，比如base64编码就是第60个字节(有些是76个字节)加一个换行，Java并无此类实现，只能手动实现，直接上代码：

public class test {

    public static String[] str_split(String str, int length) {

        int len = str.length();

        String[] arr = new String[(len + length - 1) / length];

        for (int i = 0; i < len; i += length) {

            int n = len - i;

            if (n > length)

            n = length;

            arr[i / length] = str.substring(i, i + n);

        }

        return arr;

    }

    public static String str_split(String str, int length, CharSequence delimiter) {

        return String.join(delimiter, str_split(str, length));

    }

    public static void main(String[] args) throws Exception {

        System.out.println(str_split("abcdefg", 3, " "));

    }

}