上面的方法用java怎么写

以下是用Java实现的示例代码：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        int[][] matrix = new int[n][m];
        int num = 1;
        int i = 0, j = 0;
        while (num <= n * m) {
            while (j < m && matrix[i][j] == 0) {
                matrix[i][j++] = num++;
            }
            j--;
            i++;
            while (i < n && matrix[i][j] == 0) {
                matrix[i++][j] = num++;
            }
            i--;
            j--;
            while (j >= 0 && matrix[i][j] == 0) {
                matrix[i][j--] = num++;
            }
            j++;
            i--;
            while (i >= 0 && matrix[i][j] == 0) {
                matrix[i--][j] = num++;
            }
            i++;
            j++;
        }
        for (i = 0; i < n; i++) {
            for (j = 0; j < m; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}

此代码的输出为：

输入：3 3
输出：1 2 3 
      8 9 4 
      7 6 5