如何判断一个apk是否在Java中签名？

import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.Signature;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.ApplicationInfo;
import java.io.File;

public class ApkSignatureChecker {
    public static boolean isApkSigned(String apkFilePath) {
        PackageManager pm = getPackageManager();
        PackageInfo packageInfo = pm.getPackageArchiveInfo(apkFilePath, PackageManager.GET_SIGNATURES);
        if (packageInfo != null) {
            Signature[] signatures = packageInfo.signatures;
            return signatures != null && signatures.length > 0;
        }
        return false;
    }
}