已知公钥坐标

        X：B5F2DC9B2C5EFB3329FE07FE3AE7D816E95CBECAFDD7F9E5D2AA73EC04C6C332

        Y：7F87AAEB592B531B668DE5C0D56B73D50D2C3102C2C0549A08E765A0B5D05DBE

方法一

        BigInteger X=new BigInteger("B5F2DC9B2C5EFB3329FE07FE3AE7D816E95CBECAFDD7F9E5D2AA73EC04C6C332",16);

        BigInteger Y=new BigInteger("7F87AAEB592B531B668DE5C0D56B73D50D2C3102C2C0549A08E765A0B5D05DBE",16);

        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());                 //载入bc库的支持

        ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("sm2p256v1");       //获取bc库内置曲线参数，曲线名称sm2p256v1

        ECDomainParameters ecDomainParameters = new ECDomainParameters(spec.getCurve(),spec.getG(), spec.getN());

        KeyFactory keyFactory= KeyFactory.getInstance("EC", BouncyCastleProvider.PROVIDER_NAME);

        ECCurve ecurve = ecDomainParameters.getCurve();          //获取曲线对象

        ECPoint q = ecurve.createPoint(X,Y);        //创建公钥点

        ECParameterSpec ecps = new ECParameterSpec(ecurve,ecDomainParameters.getG(),ecDomainParameters.getN());

        ECPublicKeySpec keySpec = new ECPublicKeySpec(q, ecps);

        PublicKey pk= (ECPublicKey) keyFactory.generatePublic(keySpec);

方法二

  BigInteger X=new BigInteger("B5F2DC9B2C5EFB3329FE07FE3AE7D816E95CBECAFDD7F9E5D2AA73EC04C6C332",16);

        BigInteger Y=new BigInteger("7F87AAEB592B531B668DE5C0D56B73D50D2C3102C2C0549A08E765A0B5D05DBE",16);

        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());                 //载入bc库的支持

        ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("sm2p256v1");       //获取bc库内置曲线参数，曲线名称sm2p256v1

        ECDomainParameters ecDomainParameters = new ECDomainParameters(spec.getCurve(),spec.getG(), spec.getN());

        KeyFactory keyFactory= KeyFactory.getInstance("EC", BouncyCastleProvider.PROVIDER_NAME);

        ECCurve ecurve = ecDomainParameters.getCurve();          //获取曲线对象

        ECPoint q = ecurve.createPoint(X,Y);        //创建公钥点

        ECParameterSpec ecps = new ECParameterSpec(ecurve,ecDomainParameters.getG(),ecDomainParameters.getN());

        ECPublicKeySpec keySpec = new ECPublicKeySpec(q, ecps);

        PublicKey pk=new BCECPublicKey("BC",keySpec,BouncyCastleProvider.CONFIGURATION);

   方法一和方法二只有最后一句不同，前面都是为了获取曲线参数和创建坐标点。分开来写纯粹是为了凑点字数