从谷歌云存储中获取可恢复的上传URL

Question

我正在尝试从Google云存储中获取可恢复的已签名上传网址，但我收到了无效的政策文件错误。下面是我正在使用的代码。我在这里做错了什么这里uploadUrl（）是返回最终url的那个。我发布到该网址，希望从 GCS 获取位置URI，以便我可以 PUT 我的图片，但是我得到这个错误。

// Google Service Account Client ID. Replace with your account.
@Value("${google_cloud_storage.client_account}")
private String clientAccount;

// Private key from the private_key field in the download JSON file. Replace
// this!
@Value("${google_cloud_storage.private_key}")
private String private_key;

// base url of google cloud storage objects
static final String BASE_GCS_URL = "https://storage.googleapis.com";

// bucket and object we are trying to access. Replace this!
static final String OBJECT_PATH = "/XXX.appspot.com/public/images/new.jpg";

// full url to the object.
static final String FULL_OBJECT_URL = BASE_GCS_URL + OBJECT_PATH;


public String uploadUrl() throws Exception {
    // expiry time of the url in Linux epoch form (seconds since january 1970)
    String expiryTime;

    // Set Url expiry to one minute from now!
    expiryTime = setExpiryTimeInEpoch();

    String stringToSign = getSignInput(expiryTime);
    PrivateKey pk = getPrivateKey();
    String signedString = getSignedWithSHA256(stringToSign, pk);

    // URL encode the signed string so that we can add this URL
    signedString = URLEncoder.encode(signedString, "UTF-8");

    String signedUrl = getSignedUrl(signedString, expiryTime);
    return signedUrl;
}

// Set an expiry date for the signed url. Sets it at one minute ahead of
// current time.
// Represented as the epoch time (seconds since 1st January 1970)
private String setExpiryTimeInEpoch() {
    long now = System.currentTimeMillis();
    // expire in a minute!
    // note the conversion to seconds as needed by GCS.
    long expiredTimeInSeconds = (now + 60 * 1000L) / 1000;
    return expiredTimeInSeconds + "";
}

// The signed URL format as required by Google.
private String getSignedUrl(String signedString, String expiryTime) throws Exception {
    String signedUrl = FULL_OBJECT_URL 
                       + "?GoogleAccessId=" + clientAccount 
                       + "&Expires=" + expiryTime
                       + "&Policy=" + getPolicy()
                       + "&Signature=" + signedString;
    return signedUrl;
}

String getPolicy() throws Exception {
    String fileName = "credentials/policy.json";
    ClassLoader classLoader = getClass().getClassLoader();
    File file = new File(classLoader.getResource(fileName).getFile());

    //File is found
    System.out.println("File Found : " + file.exists());

    //Read File Content
    String content = "";
    try {
        content = new String(Files.readAllBytes(file.toPath()));
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    System.out.println("Policy:" + content);

    String encodedPolicy = Base64.getEncoder().encodeToString(content.getBytes());

    String signedPolicy = getSignedWithSHA1(encodedPolicy);

    String encodedSignedPolicy = Base64.getEncoder().encodeToString(signedPolicy.getBytes());

    // URL encode the signed string so that we can add this URL
    return encodedSignedPolicy;
}

// We sign the expiry time and bucket object path
private String getSignInput(String expiryTime) {
    return "PUT" + "\n" 
                + "image/jpg" + "\n" 
                + "x-goog-resumable:start" + "\n" 
                + expiryTime + "\n" 
                + OBJECT_PATH;
}

private String getSignedWithSHA1(String input) throws Exception {
    String sha1Str;
    try {
        MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
        messageDigest.update(input.getBytes("UTF-8"));
        sha1Str = byteArrayToString(messageDigest.digest());
    } catch (Exception ignored) {
        ignored.printStackTrace();
        return null;
    }

    return Base64.getEncoder().encodeToString(sha1Str.getBytes());
}

public static String byteArrayToString(byte[] bytes) {
    StringBuilder buffer = new StringBuilder();
    for (byte b : bytes) {
        buffer.append(String.format(Locale.getDefault(), "%02x", b));
    }
    return buffer.toString();
}

// Use SHA256withRSA to sign the request
private String getSignedWithSHA256(String input, PrivateKey pk) throws Exception {
    Signature privateSignature = Signature.getInstance("SHA256withRSA");
    privateSignature.initSign(pk);
    privateSignature.update(input.getBytes("UTF-8"));
    byte[] s = privateSignature.sign();
    return Base64.getEncoder().encodeToString(s);
}

// Get private key object from unencrypted PKCS#8 file content
private PrivateKey getPrivateKey() throws Exception {
    // Remove extra characters in private key.
    String realPK = private_key.replaceAll("-----END PRIVATE KEY-----", "")
            .replaceAll("-----BEGIN PRIVATE KEY-----", "").replaceAll("\n", "");
    byte[] b1 = Base64.getDecoder().decode(realPK);
    PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(b1);
    KeyFactory kf = KeyFactory.getInstance("RSA");
    return kf.generatePrivate(spec);
}

由于