Signin.java

/*
 * Copyright 2015 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.plus.samples.quickstart;

import com.google.api.client.auth.oauth2.TokenResponseException;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeTokenRequest;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
import com.google.api.client.googleapis.auth.oauth2.GoogleTokenResponse;
import com.google.api.client.http.GenericUrl;
import com.google.api.client.http.HttpResponse;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.jackson.JacksonFactory;
import com.google.api.services.plus.Plus;
import com.google.api.services.plus.model.PeopleFeed;
import com.google.gson.Gson;

import org.mortbay.jetty.Server;
import org.mortbay.jetty.servlet.ServletHandler;
import org.mortbay.jetty.servlet.SessionHandler;

import org.apache.log4j.BasicConfigurator;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.math.BigInteger;
import java.security.SecureRandom;
import java.util.Scanner;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Simple server to demonstrate how to use Google+ Sign-In and make a request
 * via your own server.
 *
 * @author joannasmith@google.com (Joanna Smith)
 * @author vicfryzel@google.com (Vic Fryzel)
 */
public class Signin {
  /*
   * Default HTTP transport to use to make HTTP requests.
   */
  private static final HttpTransport TRANSPORT = new NetHttpTransport();

  /*
   * Default JSON factory to use to deserialize JSON.
   */
  private static final JacksonFactory JSON_FACTORY = new JacksonFactory();

  /*
   * Gson object to serialize JSON responses to requests to this servlet.
   */
  private static final Gson GSON = new Gson();

  /*
   * Creates a client secrets object from the client_secrets.json file.
   */
  private static GoogleClientSecrets clientSecrets;

  static {
    try {
      Reader reader = new FileReader("client_secrets.json");
      clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, reader);
    } catch (IOException e) {
      throw new Error("No client_secrets.json found", e);
    }
  }

  /*
   * This is the Client ID that you generated in the API Console.
   */
  private static final String CLIENT_ID = clientSecrets.getWeb().getClientId();

  /*
   * This is the Client Secret that you generated in the API Console.
   */
  private static final String CLIENT_SECRET = clientSecrets.getWeb().getClientSecret();

  /*
   * Optionally replace this with your application's name.
   */
  private static final String APPLICATION_NAME = "Google+ Java Quickstart";

  /**
   * Register all endpoints that we'll handle in our server.
   * @param args Command-line arguments.
   * @throws Exception from Jetty if the component fails to start
   */
  public static void main(String[] args) throws Exception {
    BasicConfigurator.configure();
    Server server = new Server(4567);
    ServletHandler servletHandler = new ServletHandler();
    SessionHandler sessionHandler = new SessionHandler();
    sessionHandler.setHandler(servletHandler);
    server.setHandler(sessionHandler);
    servletHandler.addServletWithMapping(ConnectServlet.class, "/connect");
    servletHandler.addServletWithMapping(DisconnectServlet.class, "/disconnect");
    servletHandler.addServletWithMapping(PeopleServlet.class, "/people");
    servletHandler.addServletWithMapping(MainServlet.class, "/");
    server.start();
    server.join();
  }

  /**
   * Initialize a session for the current user, and render index.html.
   */
  public static class MainServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
      // This check serves the signin button image
      if ("/signin_button.png".equals(request.getServletPath())) {
        File staticFile = new File("./static/signin_button.png");
        FileInputStream fileStream = new FileInputStream(staticFile);
        byte []buf = new byte[(int)staticFile.length()];
        fileStream.read(buf);
        response.setContentType("image/png");
        response.getOutputStream().write(buf);
        response.setStatus(HttpServletResponse.SC_OK);
        return;
      }

      // This check prevents the "/" handler from handling all requests by default
      if (!"/".equals(request.getServletPath())) {
        response.setStatus(HttpServletResponse.SC_NOT_FOUND);
        return;
      }

      response.setContentType("text/html");
      try {
        // Create a state token to prevent request forgery.
        // Store it in the session for later validation.
        String state = new BigInteger(130, new SecureRandom()).toString(32);
        request.getSession().setAttribute("state", state);
        // Fancy way to read index.html into memory, and set the client ID
        // and state values in the HTML before serving it.
        response.getWriter().print(new Scanner(new File("index.html"), "UTF-8")
            .useDelimiter("\\A").next()
            .replaceAll("[{]{2}\\s*CLIENT_ID\\s*[}]{2}", CLIENT_ID)
            .replaceAll("[{]{2}\\s*STATE\\s*[}]{2}", state)
            .replaceAll("[{]{2}\\s*APPLICATION_NAME\\s*[}]{2}",
                APPLICATION_NAME)
            .toString());
        response.setStatus(HttpServletResponse.SC_OK);
      } catch (FileNotFoundException e) {
        // When running the quickstart, there was some path issue in finding
        // index.html.  Double check the quickstart guide.
        e.printStackTrace();
        response.setStatus(HttpServletResponse.SC_NOT_FOUND);
        response.getWriter().print(e.toString());
      }
    }
  }

  /**
   * Upgrade given auth code to token, and store it in the session.
   * POST body of request should be the authorization code.
   * Example URI: /connect?state=...&gplus_id=...
   */
  public static class ConnectServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
      response.setContentType("application/json");

      // Only connect a user that is not already connected.
      String tokenData = (String) request.getSession().getAttribute("token");
      if (tokenData != null) {
        response.setStatus(HttpServletResponse.SC_OK);
        response.getWriter().print(GSON.toJson("Current user is already connected."));
        return;
      }
      // Ensure that this is no request forgery going on, and that the user
      // sending us this connect request is the user that was supposed to.
      if (!request.getParameter("state").equals(request.getSession().getAttribute("state"))) {
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.getWriter().print(GSON.toJson("Invalid state parameter."));
        return;
      }
      // Normally the state would be a one-time use token, however in our
      // simple case, we want a user to be able to connect and disconnect
      // without reloading the page.  Thus, for demonstration, we don't
      // implement this best practice.
      //request.getSession().removeAttribute("state");

      ByteArrayOutputStream resultStream = new ByteArrayOutputStream();
      getContent(request.getInputStream(), resultStream);
      String code = new String(resultStream.toByteArray(), "UTF-8");

      try {
        // Upgrade the authorization code into an access and refresh token.
        GoogleTokenResponse tokenResponse =
            new GoogleAuthorizationCodeTokenRequest(TRANSPORT, JSON_FACTORY,
                CLIENT_ID, CLIENT_SECRET, code, "postmessage").execute();

        // You can read the Google user ID in the ID token.
        // This sample does not use the user ID.
        GoogleIdToken idToken = tokenResponse.parseIdToken();
        String gplusId = idToken.getPayload().getSubject();

        // Store the token in the session for later use.
        request.getSession().setAttribute("token", tokenResponse.toString());
        response.setStatus(HttpServletResponse.SC_OK);
        response.getWriter().print(GSON.toJson("Successfully connected user."));
      } catch (TokenResponseException e) {
        response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        response.getWriter().print(GSON.toJson("Failed to upgrade the authorization code."));
      } catch (IOException e) {
        response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        response.getWriter().print(GSON.toJson("Failed to read token data from Google. " +
            e.getMessage()));
      }
    }

    /*
     * Read the content of an InputStream.
     *
     * @param inputStream the InputStream to be read.
     * @return the content of the InputStream as a ByteArrayOutputStream.
     * @throws IOException
     */
    static void getContent(InputStream inputStream, ByteArrayOutputStream outputStream)
        throws IOException {
      // Read the response into a buffered stream
      BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
      int readChar;
      while ((readChar = reader.read()) != -1) {
        outputStream.write(readChar);
      }
      reader.close();
    }
  }

  /**
   * Revoke current user's token and reset their session.
   */
  public static class DisconnectServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
      response.setContentType("application/json");

      // Only disconnect a connected user.
      String tokenData = (String) request.getSession().getAttribute("token");
      if (tokenData == null) {
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.getWriter().print(GSON.toJson("Current user not connected."));
        return;
      }
      try {
        // Build credential from stored token data.
        GoogleCredential credential = new GoogleCredential.Builder()
            .setJsonFactory(JSON_FACTORY)
            .setTransport(TRANSPORT)
            .setClientSecrets(CLIENT_ID, CLIENT_SECRET).build()
            .setFromTokenResponse(JSON_FACTORY.fromString(
                tokenData, GoogleTokenResponse.class));
        // Execute HTTP GET request to revoke current token.
        HttpResponse revokeResponse = TRANSPORT.createRequestFactory()
            .buildGetRequest(new GenericUrl(
                String.format(
                    "https://accounts.google.com/o/oauth2/revoke?token=%s",
                    credential.getAccessToken()))).execute();
        // Reset the user's session.
        request.getSession().removeAttribute("token");
        response.setStatus(HttpServletResponse.SC_OK);
        response.getWriter().print(GSON.toJson("Successfully disconnected."));
      } catch (IOException e) {
        // For whatever reason, the given token was invalid.
        response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
        response.getWriter().print(GSON.toJson("Failed to revoke token for given user."));
      }
    }
  }

  /**
   * Get list of people user has shared with this app.
   */
  public static class PeopleServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
      response.setContentType("application/json");

      // Only fetch a list of people for connected users.
      String tokenData = (String) request.getSession().getAttribute("token");
      if (tokenData == null) {
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.getWriter().print(GSON.toJson("Current user not connected."));
        return;
      }
      try {
        // Build credential from stored token data.
        GoogleCredential credential = new GoogleCredential.Builder()
            .setJsonFactory(JSON_FACTORY)
            .setTransport(TRANSPORT)
            .setClientSecrets(CLIENT_ID, CLIENT_SECRET).build()
            .setFromTokenResponse(JSON_FACTORY.fromString(
                tokenData, GoogleTokenResponse.class));
        // Create a new authorized API client.
        Plus service = new Plus.Builder(TRANSPORT, JSON_FACTORY, credential)
            .setApplicationName(APPLICATION_NAME)
            .build();
        // Get a list of people that this user has shared with this app.
        PeopleFeed people = service.people().list("me", "visible").execute();
        response.setStatus(HttpServletResponse.SC_OK);
        response.getWriter().print(GSON.toJson(people));
      } catch (IOException e) {
        response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        response.getWriter().print(GSON.toJson("Failed to read data from Google. " +
            e.getMessage()));
      }
    }
  }
}