在Android中从cer证书中获取公钥哈希

import android.content.res.Resources;
import java.security.MessageDigest;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import android.util.Base64;

public String getPublicKeyHash() {
    try {
        // 读取cer证书文件
        Resources res = getResources();
        int certResourceId = R.raw.certificate;
        InputStream certInputStream = res.openRawResource(certResourceId);

        // 加载证书
        CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
        X509Certificate cert = (X509Certificate) certificateFactory.generateCertificate(certInputStream);

        // 获取公钥
        byte[] publicKeyBytes = cert.getPublicKey().getEncoded();

        // 计算公钥哈希
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        byte[] publicKeyHashBytes = digest.digest(publicKeyBytes);

        // 使用Base64编码公钥哈希
        String publicKeyHash = Base64.encodeToString(publicKeyHashBytes, Base64.NO_WRAP);
        
        return publicKeyHash;
    } catch (Exception e) {
        e.printStackTrace();
    }
    
    return null;
}