Java google驱动器api凭据

我想用我存储的凭证文件，请帮帮我。桌面应用程序。我不明白如何使用保存的凭证。我没有找到关于谷歌支持的说明

private static final String APPLICATION_NAME
        = "edocsAPI";
private static final java.io.File DATA_STORE_DIR = new java.io.File(
        "E:/", ".credentials/drive-java-quickstart");
private static FileDataStoreFactory DATA_STORE_FACTORY;
private static final JsonFactory JSON_FACTORY
        = JacksonFactory.getDefaultInstance();
private static HttpTransport HTTP_TRANSPORT;
private static final List<String> SCOPES
        = Arrays.asList(DriveScopes.DRIVE_METADATA_READONLY);
static {
    try {
        HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
        DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
    } catch (Throwable t) {
        t.printStackTrace();
    }
}

public static Credential authorize() throws IOException {
    // Load client secrets.
     InputStream in
            = new FileInputStream("E:/client_secret_Rep.json");
    GoogleClientSecrets clientSecrets
            = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

    // Build flow and trigger user authorization request.
    GoogleAuthorizationCodeFlow flow
            = new GoogleAuthorizationCodeFlow.Builder(
                    HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
            .setDataStoreFactory(DATA_STORE_FACTORY)
            .setAccessType("offline")
            .build();
        Credential credential 
            = new AuthorizationCodeInstalledApp(
                    flow, new LocalServerReceiver()).authorize("user"); 

    return credential;
}

  public static Drive getDriveService() throws IOException {
    Credential credential = 
            authorize();
               System.out.println("getAccessToken" + credential.getAccessToken()); 

                 System.out.println("setAccessToken" +  credential.getAccessToken());
    System.out.println("setExpiresInSeconds" + credential.getExpiresInSeconds());

    System.out.println("setRefreshToken" + credential.getRefreshToken());
    return new Drive.Builder(
            HTTP_TRANSPORT, JSON_FACTORY, credential)
            .setApplicationName(APPLICATION_NAME)
            .build();
}

public static void main(String[] args) throws IOException {
    // Build a new authorized API client service.
    Drive service = getDriveService(); 
     FileList result = service.files().list()
     .setMaxResults(10)
     .execute();
     List<File> files = result.getItems();
     if (files == null || files.size() == 0) {
     System.out.println("No files found.");
     } else {
     System.out.println("Files:");
     for (File file : files) {
     System.out.printf("%s (%s)\n", file.getTitle(), file.getId() , file.getAlternateLink());
     file.setShared(Boolean.TRUE);
     System.out.println(file.getAlternateLink());
     }
     }

}

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但是我有一个错误401

看起来这个错误是由于访问令牌过期或无效造成的

无效的授权标头。您正在使用的访问令牌已过期或无效

下面是关于401错误的建议

---

建议的操作：使用长寿命刷新令牌刷新访问令牌。如果失败，请引导用户通过OAuth流，如中所述

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使用长寿命刷新令牌刷新访问令牌。我怎么才能找到他？我不明白

GoogleCredential credential = new GoogleCredential.Builder()
            .setTransport(new NetHttpTransport())
            .setJsonFactory(new JacksonFactory())
            .setClientSecrets("Client ID",
                    "ClientSecrets").build();

    credential.setAccessToken("AccessToken");