File-Based Credential Storage (Deprecated)

/**
 * Thread-safe file implementation of a credential store.
 * @deprecated Use FileDataStoreFactory with StoredCredential instead
 */
@Deprecated
@Beta
public class FileCredentialStore implements CredentialStore {
    
    /**
     * Creates a new file credential store.
     * @param file File to store user credentials
     * @param jsonFactory JSON factory to serialize user credentials
     * @throws IOException if file cannot be created or accessed
     */
    public FileCredentialStore(File file, JsonFactory jsonFactory) throws IOException;
    
    /**
     * Stores a credential for the specified user.
     * @param userId user ID to associate with the credential
     * @param credential credential to store
     * @throws IOException if storage fails
     */
    @Override
    public void store(String userId, Credential credential) throws IOException;
    
    /**
     * Loads a credential for the specified user.
     * @param userId user ID whose credential should be loaded
     * @param credential credential object to populate with stored values
     * @return true if credential was found and loaded, false otherwise
     */
    @Override
    public boolean load(String userId, Credential credential);
    
    /**
     * Deletes a credential for the specified user.
     * @param userId user ID whose credential should be deleted
     * @param credential credential object (not used in deletion)
     * @throws IOException if deletion fails
     */
    @Override
    public void delete(String userId, Credential credential) throws IOException;
    
    /**
     * Migrates to the new FileDataStoreFactory format.
     * @param dataStoreFactory file data store factory for migration target
     * @throws IOException if migration fails
     */
    public final void migrateTo(FileDataStoreFactory dataStoreFactory) throws IOException;
    
    /**
     * Migrates to the new format using DataStore of StoredCredential.
     * @param credentialDataStore credential data store for migration target
     * @throws IOException if migration fails
     */
    public final void migrateTo(DataStore<StoredCredential> credentialDataStore) throws IOException;
    
    /**
     * Returns whether the given file is a symbolic link.
     * @param file file to check for symbolic link
     * @return true if file is a symbolic link, false otherwise
     * @throws IOException if file system check fails
     */
    protected boolean isSymbolicLink(File file) throws IOException;
}

import com.google.api.client.extensions.java6.auth.oauth2.FileCredentialStore;
import com.google.api.client.json.gson.GsonFactory;
import java.io.File;

// Create credential store (deprecated approach)
File credentialFile = new File(System.getProperty("user.home"), ".oauth_credentials");
FileCredentialStore store = new FileCredentialStore(credentialFile, GsonFactory.getDefaultInstance());

// Store credential
Credential credential = // ... obtained from OAuth flow
store.store("user123", credential);

// Load credential
Credential loadedCredential = new Credential.Builder(BearerToken.authorizationHeaderAccessMethod())
    .setTransport(httpTransport)
    .setJsonFactory(jsonFactory)
    .setTokenServerUrl(tokenServerUrl)
    .setClientAuthentication(clientAuthentication)
    .build();
    
boolean found = store.load("user123", loadedCredential);
if (found) {
    System.out.println("Credential loaded successfully");
}

/**
 * Persisted credential implementation to be used exclusively with FileCredentialStore.
 * @deprecated Use FileDataStoreFactory instead
 */
@Deprecated
@Beta
public class FilePersistedCredentials extends GenericJson {
    
    // Package-visible methods used internally by FileCredentialStore
    void store(String userId, Credential credential);
    boolean load(String userId, Credential credential);
    void delete(String userId);
    void migrateTo(DataStore<StoredCredential> typedDataStore) throws IOException;
    
    // Inherited from GenericJson
    @Override
    public FilePersistedCredentials set(String fieldName, Object value);
    
    @Override
    public FilePersistedCredentials clone();
}

/**
 * Persisted credential implementation to be used exclusively with FileCredentialStore.
 * @deprecated Use FileDataStoreFactory instead
 */
@Deprecated
@Beta
public class FilePersistedCredential extends GenericJson {
    
    // Package-visible methods used internally
    void store(Credential credential);
    void load(Credential credential);
    StoredCredential toStoredCredential();
    
    // Inherited from GenericJson
    @Override
    public FilePersistedCredential set(String fieldName, Object value);
    
    @Override
    public FilePersistedCredential clone();
}

// Deprecated approach
File credentialFile = new File(".oauth_credentials");
FileCredentialStore store = new FileCredentialStore(credentialFile, jsonFactory);

AuthorizationCodeFlow flow = new AuthorizationCodeFlow.Builder(
    // ... other parameters
    ).setCredentialStore(store)
    .build();

// Recommended approach
File dataStoreDir = new File(System.getProperty("user.home"), ".credentials");
FileDataStoreFactory dataStoreFactory = new FileDataStoreFactory(dataStoreDir);
DataStore<StoredCredential> dataStore = StoredCredential.getDefaultDataStore(dataStoreFactory);

AuthorizationCodeFlow flow = new AuthorizationCodeFlow.Builder(
    // ... other parameters
    ).setCredentialDataStore(dataStore)
    .build();

// Migrate existing FileCredentialStore to new format
FileCredentialStore oldStore = new FileCredentialStore(oldFile, jsonFactory);
FileDataStoreFactory newDataStoreFactory = new FileDataStoreFactory(newDataDirectory);

// Perform migration
oldStore.migrateTo(newDataStoreFactory);

// Or migrate to specific DataStore
DataStore<StoredCredential> newDataStore = StoredCredential.getDefaultDataStore(newDataStoreFactory);
oldStore.migrateTo(newDataStore);

{
  "credentials": {
    "user123": {
      "access_token": "ya29.a0AfH6SMC...",
      "refresh_token": "1//04...",
      "expiration_time_millis": 1635724800000
    },
    "user456": {
      "access_token": "ya29.a0AfH6SMD...",
      "refresh_token": "1//05...",
      "expiration_time_millis": 1635728400000
    }
  }
}