公钥获取接口：

https://pay.weixin.qq.com/wiki/doc/api/tools/mch_pay_yhk.php?chapter=24_7&index=4

我的做法是用postman固定随机值（和文档示例给的随机值一样32位）后请求这个接口，获得了公钥，然后存到txt，后缀改为pem。公钥如下：

然后用工具类获取了InputStream（公钥pem文件）的字符串，并且打印正常，测试环境正常，生成环境也正常。

接下来要将公钥转为PublicKey类型，有两种方法，两种方法都报了不一样的异常。

1传入参数为公钥字符串（已打印确定就是接口获取到的公钥）

public static PublicKey getPublicKey(String key) throws Exception {
    byte[] keyBytes;
    keyBytes = (new BASE64Decoder()).decodeBuffer(key);
    X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    PublicKey publicKey = keyFactory.generatePublic(keySpec);-----------------------------本行是报异常的具体位置
    return publicKey;
}

异常：

java.security.InvalidKeyException: IOException : Short read of DER length

2传入参数为InputStream

public static PublicKey getPublicKey(InputStream inputStream, String keyAlgorithm) throws Exception {
    try
    {
        System.out.println("b1.........");
        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
        System.out.println("b2.........");
        StringBuilder sb = new StringBuilder();
        String readLine = null;
        System.out.println("b3.........");
        while ((readLine = br.readLine()) != null) {
            if (readLine.charAt(0) == '-') {
                continue;
            } else {
                sb.append(readLine);
                sb.append('\r');
            }
        }
        System.out.println("b4.........");
        X509EncodedKeySpec pubX509 = new X509EncodedKeySpec(decodeBase64(sb.toString()));
        System.out.println("b5.........");
        KeyFactory keyFactory = KeyFactory.getInstance(keyAlgorithm);
        System.out.println("b6.........");
        //下行出错  java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException: DerInputStream.getLength(): lengthTag=127, too big.
        PublicKey publicKey = keyFactory.generatePublic(pubX509);-----------------------------本行是报异常的具体位置

        System.out.println("b7.........");
        return publicKey;
    } catch (Exception e) {
        e.printStackTrace();
        System.out.println("b8.........");
        throw new Exception("1这里报异常了："+e.getMessage(), e);
    } finally {
        try {
            if (inputStream != null) {
                inputStream.close();
            }
        } catch (IOException e) {
            inputStream = null;
            throw new Exception("INPUT STREAM CLOSE ERROR:", e);
        }
    }

异常：

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException: algid parse error, not a sequence

我正在做的是企业转账到银行卡功能，请问我这个步骤正确吗？如果正确，那这异常什么原因，要如何解决？