判断ip地址是否合法

package day13; import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) {
        Scanner scanner = new Scanner(
                System.in); // 创建Scanner对象并传入标准输入流（键盘）作为参数  String addStr = scanner.nextLine();  if (addStr.equals("") || addStr == null) {
            System.out.println("invalid");  return;  } //String addStr = "195.25.3.4";  char c1 = addStr.charAt(0);  char c2 = addStr.charAt(addStr.length() - 1);  String s1 = Character.toString(c1);  String s2 = Character.toString(c2);  String[] strings = new String[]{ "1", "2", "3", "4", "5", "6", "7", "8", "9", "0"  };  int temp = 0;  for (String string : strings) { if (string.equals(s1)) {
                temp++;  } if (string.equals(s2)) {
                temp++;  }
        } if (temp != 2) {
            System.out.println("invalid");  return;  }
        String[] split = addStr.split("\\.");  if (split.length != 4) {
            System.out.println("invalid");  return;  } for (String s : split) { if (s.length() == 2 && Character.toString(s.charAt(0)).equals("0")) {
                System.out.println("invalid");  return;  }
        } for (int i = 0; i < split.length; i++) { try { if (Integer.parseInt(split[i]) > 255) {
                    System.out.println("invalid");  return;  }
            } catch (NumberFormatException e) {
                System.out.println("invalid");  return;  }
        } int address1 = Integer.parseInt(split[0]);  int address2 = Integer.parseInt(split[1]);  int address3 = Integer.parseInt(split[2]);  int address4 = Integer.parseInt(split[3]);  if (address1 < 126 && address1 > 0 || address1 == 126 && address2 == 0 && address3 == 0 && address4 == 0) {
            System.out.println("A_address");  } else if (address1 >= 128 && address1 <= 191) {
            System.out.println("B_address");  } else if (address1 >= 192 && address1 <= 223) {
            System.out.println("C_address");  } else {
            System.out.println("other");  }
    }
}