解题思路：

class Solution {
    public int[] spiralArray(int[][] array) {
        if(array.length == 0) return new int[0];

        int l = 0, r = array[0].length - 1;
        int t = 0, b = array.length - 1;
        int x = 0;
        int[] res = new int[(r + 1) * (b + 1)];

        while(true) {
            for(int i = l; i <= r; i++) res[x++] = array[t][i]; //从左到右
            if(++t > b) break;
            for(int i = t; i <= b; i++) res[x++] = array[i][r]; //从上到下
            if(--r < l) break;
            for(int i = r; i >= l; i--) res[x++] = array[b][i]; //从右到左
            if(--b < t) break;
            for(int i = b; i >= t; i--) res[x++] = array[i][l]; //从下到上
            if(++l > r) break;
        }
        return res;
    }
}