java实现 pem格式ecc公钥计算x、y分量

以下是Java代码实现PEM格式ECC公钥计算x、y分量的示例：

import java.io.BufferedReader;
import java.io.FileReader;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.spec.ECPoint;
import java.security.spec.ECPublicKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class ECCPublicKeyParser {

    public static void main(String[] args) throws Exception {
        // 读取PEM格式的ECC公钥
        BufferedReader br = new BufferedReader(new FileReader("ecc_public_key.pem"));
        String line;
        StringBuilder sb = new StringBuilder();
        while ((line = br.readLine()) != null) {
            if (!line.startsWith("-----")) {
                sb.append(line);
            }
        }
        br.close();
        String pemStr = sb.toString();

        // 解码PEM格式的ECC公钥
        byte[] derBytes = Base64.getDecoder().decode(pemStr);
        X509EncodedKeySpec spec = new X509EncodedKeySpec(derBytes);
        KeyFactory kf = KeyFactory.getInstance("EC");
        PublicKey publicKey = kf.generatePublic(spec);

        // 获取ECC公钥的参数
        ECPublicKeySpec ecSpec = kf.getKeySpec(publicKey, ECPublicKeySpec.class);
        ECPoint point = ecSpec.getW();
        byte[] x = point.getAffineX().toByteArray();
        byte[] y = point.getAffineY().toByteArray();

        // 输出ECC公钥的x、y分量
        System.out.println("x = " + bytesToHex(x));
        System.out.println("y = " + bytesToHex(y));
    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            sb.append(String.format("%02X", b));
        }
        return sb.toString();
    }
}

在上述代码中，我们首先读取PEM格式的ECC公钥文件，然后解码成DER格式的字节数组。接着，我们使用`KeyFactory`类将DER格式的字节数组转换成`PublicKey`对象，再从`PublicKey`对象中获取ECC公钥的参数。最后，我们将ECC公钥的x、y分量以16进制字符串形式输出。