public static SignatureUtil buildInstance(String privateKey, String publicKey,
                                              Algorithms algorithms) {
        return new SignatureUtilImpl(privateKey, publicKey, algorithms);
    }
public static SignatureUtil buildInstance ( String privateKey , String publicKey , Algorithms algorithms ) { return new SignatureUtilImpl ( privateKey , publicKey , algorithms ) ; }
构建一个SignatureUtil

@param privateKey PKCS8文件格式的私钥
@param publicKey  X509格式的公钥
@param algorithms RSA加密类型
@return SignatureUtil