Build-Autorisierungs-Callback-Handler

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

 <servlet>
   <servlet-name>PrintTasksTitles</servlet-name>
   <servlet-class>com.google.oauthsample.PrintTasksTitlesServlet</servlet-class>
 </servlet>

 <servlet-mapping>
   <servlet-name>PrintTasksTitles</servlet-name>
   <url-pattern>/</url-pattern>
 </servlet-mapping>

 <servlet>
   <servlet-name>OAuthCodeCallbackHandlerServlet</servlet-name>
   <servlet-class>com.google.oauthsample.OAuthCodeCallbackHandlerServlet</servlet-class>
 </servlet>

 <servlet-mapping>
   <servlet-name>OAuthCodeCallbackHandlerServlet</servlet-name>
   <url-pattern>/oauth2callback</url-pattern>
 </servlet-mapping>

</web-app>

package com.google.oauthsample;

import ...

/**
 * Simple sample Servlet which will display the tasks in the default task list of the user.
 */
@SuppressWarnings("serial")
public class PrintTasksTitlesServlet extends HttpServlet {

  /**
   * The OAuth Token DAO implementation, used to persist the OAuth refresh token.
   * Consider injecting it instead of using a static initialization. Also we are
   * using a simple memory implementation as a mock. Change the implementation to
   * using your database system.
   */
  public static OAuthTokenDao oauthTokenDao = new OAuthTokenDaoMemoryImpl();

  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    // Getting the current user
    // This is using App Engine's User Service but you should replace this to
    // your own user/login implementation
    UserService userService = UserServiceFactory.getUserService();
    User user = userService.getCurrentUser();

    // If the user is not logged-in it is redirected to the login service, then back to this page
    if (user == null) {
      resp.sendRedirect(userService.createLoginURL(getFullRequestUrl(req)));
      return;
    }

    // Checking if we already have tokens for this user in store
    AccessTokenResponse accessTokenResponse = oauthTokenDao.getKeys(user.getEmail());

    // If we don't have tokens for this user
    if (accessTokenResponse == null) {
      OAuthProperties oauthProperties = new OAuthProperties();
      // Redirect to the Google OAuth 2.0 authorization endpoint
      resp.sendRedirect(new GoogleAuthorizationRequestUrl(oauthProperties.getClientId(),
          OAuthCodeCallbackHandlerServlet.getOAuthCodeCallbackHandlerUrl(req), oauthProperties
              .getScopesAsString()).build());
      return;
    }
  }

  /**
   * Construct the request's URL without the parameter part.
   *
   * @param req the HttpRequest object
   * @return The constructed request's URL
   */
  public static String getFullRequestUrl(HttpServletRequest req) {
    String scheme = req.getScheme() + "://";
    String serverName = req.getServerName();
    String serverPort = (req.getServerPort() == 80) ? "" : ":" + req.getServerPort();
    String contextPath = req.getContextPath();
    String servletPath = req.getServletPath();
    String pathInfo = (req.getPathInfo() == null) ? "" : req.getPathInfo();
    String queryString = (req.getQueryString() == null) ? "" : "?" + req.getQueryString();
    return scheme + serverName + serverPort + contextPath + servletPath + pathInfo + queryString;
  }
}

package com.google.oauthsample;

import com.google.api.client.auth.oauth2.draft10.AccessTokenResponse;

/**
 * Allows easy storage and access of authorization tokens.
 */
public interface OAuthTokenDao {

  /**
   * Stores the given AccessTokenResponse using the {@code username}, the OAuth
   * {@code clientID} and the tokens scopes as keys.
   *
   * @param tokens The AccessTokenResponse to store
   * @param userName The userName associated wit the token
   */
  public void saveKeys(AccessTokenResponse tokens, String userName);

  /**
   * Returns the AccessTokenResponse stored for the given username, clientId and
   * scopes. Returns {@code null} if there is no AccessTokenResponse for this
   * user and scopes.
   *
   * @param userName The username of which to get the stored AccessTokenResponse
   * @return The AccessTokenResponse of the given username
   */
  public AccessTokenResponse getKeys(String userName);
}

package com.google.oauthsample;

import com.google.api.client.auth.oauth2.draft10.AccessTokenResponse;
...

/**
 * Quick and Dirty memory implementation of {@link OAuthTokenDao} based on
 * HashMaps.
 */
public class OAuthTokenDaoMemoryImpl implements OAuthTokenDao {

  /** Object where all the Tokens will be stored */
  private static Map<String, AccessTokenResponse> tokenPersistance = new HashMap<String, AccessTokenResponse>();

  public void saveKeys(AccessTokenResponse tokens, String userName) {
    tokenPersistance.put(userName, tokens);
  }

  public AccessTokenResponse getKeys(String userName) {
    return tokenPersistance.get(userName);
  }
}

package com.google.oauthsample;

import ...

/**
 * Object representation of an OAuth properties file.
 */
public class OAuthProperties {

  public static final String DEFAULT_OAUTH_PROPERTIES_FILE_NAME = "oauth.properties";

  /** The OAuth 2.0 Client ID */
  private String clientId;

  /** The OAuth 2.0 Client Secret */
  private String clientSecret;

  /** The Google APIs scopes to access */
  private String scopes;

  /**
   * Instantiates a new OauthProperties object reading its values from the
   * {@code OAUTH_PROPERTIES_FILE_NAME} properties file.
   *
   * @throws IOException IF there is an issue reading the {@code propertiesFile}
   * @throws OauthPropertiesFormatException If the given {@code propertiesFile}
   *           is not of the right format (does not contains the keys {@code
   *           clientId}, {@code clientSecret} and {@code scopes})
   */
  public OAuthProperties() throws IOException {
    this(OAuthProperties.class.getResourceAsStream(DEFAULT_OAUTH_PROPERTIES_FILE_NAME));
  }

  /**
   * Instantiates a new OauthProperties object reading its values from the given
   * properties file.
   *
   * @param propertiesFile the InputStream to read an OAuth Properties file. The
   *          file should contain the keys {@code clientId}, {@code
   *          clientSecret} and {@code scopes}
   * @throws IOException IF there is an issue reading the {@code propertiesFile}
   * @throws OAuthPropertiesFormatException If the given {@code propertiesFile}
   *           is not of the right format (does not contains the keys {@code
   *           clientId}, {@code clientSecret} and {@code scopes})
   */
  public OAuthProperties(InputStream propertiesFile) throws IOException {
    Properties oauthProperties = new Properties();
    oauthProperties.load(propertiesFile);
    clientId = oauthProperties.getProperty("clientId");
    clientSecret = oauthProperties.getProperty("clientSecret");
    scopes = oauthProperties.getProperty("scopes");
    if ((clientId == null) || (clientSecret == null) || (scopes == null)) {
      throw new OAuthPropertiesFormatException();
    }
  }

  /**
   * @return the clientId
   */
  public String getClientId() {
    return clientId;
  }

  /**
   * @return the clientSecret
   */
  public String getClientSecret() {
    return clientSecret;
  }

  /**
   * @return the scopes
   */
  public String getScopesAsString() {
    return scopes;
  }

  /**
   * Thrown when the OAuth properties file was not at the right format, i.e not
   * having the right properties names.
   */
  @SuppressWarnings("serial")
  public class OAuthPropertiesFormatException extends RuntimeException {
  }
}

# Client ID and secret. They can be found in the APIs console.
clientId=1234567890.apps.googleusercontent.com
clientSecret=aBcDeFgHiJkLmNoPqRsTuVwXyZ
# API scopes. Space separated.
scopes=https://www.googleapis.com/auth/tasks

new GoogleAuthorizationRequestUrl(oauthProperties.getClientId(),
      OAuthCodeCallbackHandlerServlet.getOAuthCodeCallbackHandlerUrl(req), oauthProperties
          .getScopesAsString()).build()

package com.google.oauthsample;

import ...

/**
 * Servlet handling the OAuth callback from the authentication service. We are
 * retrieving the OAuth code, then exchanging it for a refresh and an access
 * token and saving it.
 */
@SuppressWarnings("serial")
public class OAuthCodeCallbackHandlerServlet extends HttpServlet {

  /** The name of the Oauth code URL parameter */
  public static final String CODE_URL_PARAM_NAME = "code";

  /** The name of the OAuth error URL parameter */
  public static final String ERROR_URL_PARAM_NAME = "error";

  /** The URL suffix of the servlet */
  public static final String URL_MAPPING = "/oauth2callback";

  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    // Getting the "error" URL parameter
    String[] error = req.getParameterValues(ERROR_URL_PARAM_NAME);

    // Checking if there was an error such as the user denied access
    if (error != null && error.length > 0) {
      resp.sendError(HttpServletResponse.SC_NOT_ACCEPTABLE, "There was an error: \""+error[0]+"\".");
      return;
    }
    // Getting the "code" URL parameter
    String[] code = req.getParameterValues(CODE_URL_PARAM_NAME);

    // Checking conditions on the "code" URL parameter
    if (code == null || code.length == 0) {
      resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "The \"code\" URL parameter is missing");
      return;
    }
  }

  /**
   * Construct the OAuth code callback handler URL.
   *
   * @param req the HttpRequest object
   * @return The constructed request's URL
   */
  public static String getOAuthCodeCallbackHandlerUrl(HttpServletRequest req) {
    String scheme = req.getScheme() + "://";
    String serverName = req.getServerName();
    String serverPort = (req.getServerPort() == 80) ? "" : ":" + req.getServerPort();
    String contextPath = req.getContextPath();
    String servletPath = URL_MAPPING;
    String pathInfo = (req.getPathInfo() == null) ? "" : req.getPathInfo();
    return scheme + serverName + serverPort + contextPath + servletPath + pathInfo;
  }
}

package com.google.oauthsample;

import ...

/**
 * Servlet handling the OAuth callback from the authentication service. We are
 * retrieving the OAuth code, then exchanging it for a refresh and an access
 * token and saving it.
 */
@SuppressWarnings("serial")
public class OAuthCodeCallbackHandlerServlet extends HttpServlet {

  /** The name of the Oauth code URL parameter */
  public static final String CODE_URL_PARAM_NAME = "code";

  /** The name of the OAuth error URL parameter */
  public static final String ERROR_URL_PARAM_NAME = "error";

  /** The URL suffix of the servlet */
  public static final String URL_MAPPING = "/oauth2callback";
  /** Die URL, zu der der Nutzer nach der Verarbeitung des Callbacks weitergeleitet werden soll. Du kannst diese Informationen in einem Cookie speichern, bevor du Nutzer zur Autorisierungs-URL von Google weiterleitest, wenn du mehrere URLs hast, zu denen Nutzer weitergeleitet werden können. */
  public static final String REDIRECT_URL = "/";

  /** Die OAuth-Token-DAO-Implementierung. Sie können sie einschleusen, anstatt eine statische Initialisierung zu verwenden. Außerdem verwenden wir eine einfache Speicherimplementierung als Mock. Ändern Sie die Implementierung so, dass Ihr Datenbanksystem verwendet wird. */
  public static OAuthTokenDao oauthTokenDao = new OAuthTokenDaoMemoryImpl();

  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    // Getting the "error" URL parameter
    String[] error = req.getParameterValues(ERROR_URL_PARAM_NAME);

    // Checking if there was an error such as the user denied access
    if (error != null && error.length > 0) {
      resp.sendError(HttpServletResponse.SC_NOT_ACCEPTABLE, "There was an error: \""+error[0]+"\".");
      return;
    }

    // Getting the "code" URL parameter
    String[] code = req.getParameterValues(CODE_URL_PARAM_NAME);

    // Checking conditions on the "code" URL parameter
    if (code == null || code.length == 0) {
      resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "The \"code\" URL parameter is missing");
      return;
    }
    // Construct incoming request URL
    String requestUrl = getOAuthCodeCallbackHandlerUrl(req);

    // Exchange the code for OAuth tokens
    AccessTokenResponse accessTokenResponse = exchangeCodeForAccessAndRefreshTokens(code[0],
        requestUrl);

    // Getting the current user
    // This is using App Engine's User Service but you should replace this to
    // your own user/login implementation
    UserService userService = UserServiceFactory.getUserService();
    String email = userService.getCurrentUser().getEmail();

    // Save the tokens
    oauthTokenDao.saveKeys(accessTokenResponse, email);

    resp.sendRedirect(REDIRECT_URL);
  }

  /**
   * Construct the OAuth code callback handler URL.
   *
   * @param req the HttpRequest object
   * @return The constructed request's URL
   */
  public static String getOAuthCodeCallbackHandlerUrl(HttpServletRequest req) {
    String scheme = req.getScheme() + "://";
    String serverName = req.getServerName();
    String serverPort = (req.getServerPort() == 80) ? "" : ":" + req.getServerPort();
    String contextPath = req.getContextPath();
    String servletPath = URL_MAPPING;
    String pathInfo = (req.getPathInfo() == null) ? "" : req.getPathInfo();
    return scheme + serverName + serverPort + contextPath + servletPath + pathInfo;
  }
  /**
   * Tauschen Sie den angegebenen Code gegen ein Exchange- und ein Aktualisierungstoken aus.
   *
   * @param code Der vom Autorisierungsdienst zurückgegebene Code
   * @param currentUrl Die URL des Callbacks
   * @param oauthProperties Das Objekt mit der OAuth-Konfiguration
   * @return Das Objekt mit einem Zugriffs- und einem Aktualisierungstoken
   * @throws IOException
   */
  public AccessTokenResponse exchangeCodeForAccessAndRefreshTokens(String code, String currentUrl)
      throws IOException {

    HttpTransport httpTransport = new NetHttpTransport();
    JacksonFactory jsonFactory = new JacksonFactory();

    // Loading the oauth config file
    OAuthProperties oauthProperties = new OAuthProperties();

    return new GoogleAuthorizationCodeGrant(httpTransport, jsonFactory, oauthProperties
        .getClientId(), oauthProperties.getClientSecret(), code, currentUrl).execute();
  }
}

Datei „OAuthCodeCallbackHandlerServlet.java“

Hinweis: In der obigen Implementierung werden einige App Engine-Bibliotheken verwendet, um die Sache zu vereinfachen. Wenn Sie für eine andere Plattform entwickeln, können Sie die Schnittstelle UserService, die für die Nutzerauthentifizierung zuständig ist, neu implementieren.

Aufgaben des Nutzers lesen und anzeigen

Der Nutzer hat der Anwendung Zugriff auf seine Aufgaben gewährt. Die Anwendung hat ein Aktualisierungstoken, das im Datenspeicher gespeichert wird, auf den über den OAuthTokenDao zugegriffen werden kann. Das Servlet PrintTaskListsTitlesServlet kann jetzt diese Tokens verwenden, um auf die Aufgaben des Nutzers zuzugreifen und sie anzuzeigen:

Der der Datei unten hinzugefügte Code ist syntaxfarbig hervorgehoben, der bereits vorhandene Code ist ausgegraut.

package com.google.oauthsample;

import ...

/**
 * Simple sample Servlet which will display the tasks in the default task list of the user.
 */
@SuppressWarnings("serial")
public class PrintTasksTitlesServlet extends HttpServlet {

  /**
   * The OAuth Token DAO implementation, used to persist the OAuth refresh token.
   * Consider injecting it instead of using a static initialization. Also we are
   * using a simple memory implementation as a mock. Change the implementation to
   * using your database system.
   */
  public static OAuthTokenDao oauthTokenDao = new OAuthTokenDaoMemoryImpl();

  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    // Getting the current user
    // This is using App Engine's User Service but you should replace this to
    // your own user/login implementation
    UserService userService = UserServiceFactory.getUserService();
    User user = userService.getCurrentUser();

    // If the user is not logged-in it is redirected to the login service, then back to this page
    if (user == null) {
      resp.sendRedirect(userService.createLoginURL(getFullRequestUrl(req)));
      return;
    }

    // Checking if we already have tokens for this user in store
    AccessTokenResponse accessTokenResponse = oauthTokenDao.getKeys(user.getEmail());

    // If we don't have tokens for this user
    if (accessTokenResponse == null) {
      OAuthProperties oauthProperties = new OAuthProperties();
      // Redirect to the Google OAuth 2.0 authorization endpoint
      resp.sendRedirect(new GoogleAuthorizationRequestUrl(oauthProperties.getClientId(),
          OAuthCodeCallbackHandlerServlet.getOAuthCodeCallbackHandlerUrl(req), oauthProperties
              .getScopesAsString()).build());
      return;
    }
    // Titel der Aufgabenlisten des Nutzers in der Antwort ausgeben
    resp.setContentType("text/plain");
    resp.getWriter().append("Titel der Aufgabenlisten für Nutzer " + user.getEmail() + ":\n\n");
    printTasksTitles(accessTokenResponse, resp.getWriter());
  }

  /**
   * Construct the request's URL without the parameter part.
   *
   * @param req the HttpRequest object
   * @return The constructed request's URL
   */
  public static String getFullRequestUrl(HttpServletRequest req) {
    String scheme = req.getScheme() + "://";
    String serverName = req.getServerName();
    String serverPort = (req.getServerPort() == 80) ? "" : ":" + req.getServerPort();
    String contextPath = req.getContextPath();
    String servletPath = req.getServletPath();
    String pathInfo = (req.getPathInfo() == null) ? "" : req.getPathInfo();
    String queryString = (req.getQueryString() == null) ? "" : "?" + req.getQueryString();
    return scheme + serverName + serverPort + contextPath + servletPath + pathInfo + queryString;
  }
  /**
   * Ruft mit der Google Tasks API eine Liste der Aufgaben der Nutzer in der Standardaufgabenliste ab.
   *
   * @param accessTokenResponse Das OAuth 2.0-AccessTokenResponse-Objekt mit dem Zugriffs- und dem Aktualisierungstoken.
   * @param output der Outputstream-Writer, in den die Titel der Aufgabenlisten geschrieben werden sollen
   * @return Eine Liste der Aufgabentitel der Nutzer in der Standardaufgabenliste.
   * @throws IOException
   */
  public void printTasksTitles(AccessTokenResponse accessTokenResponse, Writer output) throws IOException {

    // Initializing the Tasks service
    HttpTransport transport = new NetHttpTransport();
    JsonFactory jsonFactory = new JacksonFactory();
    OAuthProperties oauthProperties = new OAuthProperties();

    GoogleAccessProtectedResource accessProtectedResource = new GoogleAccessProtectedResource(
        accessTokenResponse.accessToken, transport, jsonFactory, oauthProperties.getClientId(),
        oauthProperties.getClientSecret(), accessTokenResponse.refreshToken);

    Tasks service = new Tasks(transport, accessProtectedResource, jsonFactory);

    // Using the initialized Tasks API service to query the list of tasks lists
    com.google.api.services.tasks.model.Tasks tasks = service.tasks.list("@default").execute();

    for (Task task : tasks.items) {
      output.append(task.title + "\n");
    }
  }
}

Datei „PrintTasksTitlesServlet.java“

Dem Nutzer werden seine Aufgaben angezeigt:


  
  
Die Aufgaben der Nutzer


Beispielanwendung

Den Code für diese Beispielanwendung können Sie hier herunterladen. Sie können sich das gerne ansehen.