如何在java中正确验证PNG头？

import java.io.FileInputStream;
import java.io.IOException;

public class PNGHeaderValidator {
    public static void main(String[] args) {
        String filePath = "path/to/png/file.png";
        try (FileInputStream fis = new FileInputStream(filePath)) {
            byte[] header = new byte[8];
            fis.read(header);
            byte[] expectedHeader = { (byte) 137, 80, 78, 71, 13, 10, 26, 10 };
            if (isHeaderValid(header, expectedHeader)) {
                System.out.println("Valid PNG file.");
            } else {
                System.out.println("Invalid PNG file.");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static boolean isHeaderValid(byte[] header, byte[] expectedHeader) {
        if (header.length != expectedHeader.length) {
            return false;
        }
        for (int i = 0; i < header.length; i++) {
            if (header[i] != expectedHeader[i]) {
                return false;
            }
        }
        return true;
    }
}