com.mxgraph.online.dredit.DrEditServlet.java Source code

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Here is the source code for com.mxgraph.online.dredit.DrEditServlet.java

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/*
 * Copyright (c) 2012 Google Inc.
 *
 * 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.mxgraph.online.dredit;

import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;

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

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson.JacksonFactory;
import com.google.api.services.oauth2.model.Userinfo;
import com.mxgraph.online.dredit.CredentialMediator.CodeExchangeException;
import com.mxgraph.online.dredit.CredentialMediator.NoRefreshTokenException;
import com.mxgraph.online.dredit.CredentialMediator.NoUserIdException;

/**
 * Abstract servlet that sets up credentials and provides some convenience
 * methods.
 *
 * @author vicfryzel@google.com (Vic Fryzel)
 */
public abstract class DrEditServlet extends HttpServlet {
    protected static final HttpTransport TRANSPORT = new NetHttpTransport();

    protected static final JsonFactory JSON_FACTORY = new JacksonFactory();

    /**
     * Default MIME type of files created or handled by DrEdit.
     *
     * This is also set in the Google APIs Console under the Drive SDK tab.
     */
    public static final String DEFAULT_MIMETYPE = "application/mxe";

    /**
     * MIME type to use when sending responses back to DrEdit JavaScript client.
     */
    public static final String JSON_MIMETYPE = "application/json;charset=utf-8";

    /**
     * Path component under war/ to locate client_secrets.json file.
     */
    public static final String CLIENT_SECRETS_FILE_PATH = "/WEB-INF/client_secrets.json";

    /**
     * Loaded data from war/WEB-INF/client_secrets.json.
     */
    protected GoogleClientSecrets secrets;

    /**
     * Loads the secrets.
     */
    protected void updateSecrets() {
        if (secrets == null) {
            try {
                secrets = GoogleClientSecrets.load(JSON_FACTORY, getClientSecretsStream());
            } catch (IOException e) {
                throw new RuntimeException("client_secrets.json is missing or invalid.");
            }
        }
    }

    /**
     * Scopes for which to request access from the user.
     */
    public static final List<String> SCOPES = Arrays.asList(
            // Required to access and manipulate files.
            "https://www.googleapis.com/auth/drive.file",
            // Required to identify the user in our data store.
            "https://www.googleapis.com/auth/userinfo.email", "https://www.googleapis.com/auth/userinfo.profile");

    protected void sendError(HttpServletResponse resp, int code, String message) {
        try {
            resp.sendError(code, message);
        } catch (IOException e) {
            throw new RuntimeException(message);
        }
    }

    protected InputStream getClientSecretsStream() {
        return getServletContext().getResourceAsStream(CLIENT_SECRETS_FILE_PATH);
    }

    protected CredentialMediator getCredentialMediator(HttpServletRequest req, HttpServletResponse resp)
            throws CredentialMediator.NoRefreshTokenException {
        // Authorize or fetch credentials.  Required here to ensure this happens
        // on first page load.  Then, credentials will be stored in the user's
        // session.
        updateSecrets();
        CredentialMediator mediator = new CredentialMediator(req, resp, secrets);
        mediator.getActiveCredential();
        return mediator;
    }

    protected Credential getCredential(HttpServletRequest req, HttpServletResponse resp) {
        try {
            CredentialMediator mediator = getCredentialMediator(req, resp);
            return mediator.getActiveCredential();
        } catch (CredentialMediator.NoRefreshTokenException e) {
            throw new RuntimeException("No refresh token found. Re-authorizing.");
        }
    }

    protected String getClientId(HttpServletRequest req, HttpServletResponse resp)
            throws CredentialMediator.NoRefreshTokenException {
        return getCredentialMediator(req, resp).getClientSecrets().getWeb().getClientId();
    }

    protected void deleteCredential(HttpServletRequest req, HttpServletResponse resp) {
        try {
            CredentialMediator mediator = getCredentialMediator(req, resp);
            mediator.deleteActiveCredential();
        } catch (CredentialMediator.NoRefreshTokenException e) {
            throw new RuntimeException("Failed to redirect for authorization.");
        }
    }

    protected boolean shouldInvalidateSession(HttpServletRequest request, CredentialMediator mediator) {
        boolean invalidate = false;

        String authCode = request.getParameter("code");
        String sessionUserId = (String) request.getSession().getAttribute(CredentialMediator.USER_ID_KEY);

        if (authCode != null && sessionUserId != null) {
            try {
                Credential cred = mediator.exchangeCode(authCode);
                Userinfo ui = mediator.getUserInfo(cred);
                invalidate = !sessionUserId.equals(ui.getId());
            } catch (NoUserIdException e) {
                e.printStackTrace();
            } catch (CodeExchangeException e) {
                e.printStackTrace();
            }
        }

        return invalidate;
    }

    protected void endSession(HttpServletRequest request, HttpServletResponse response, CredentialMediator mediator)
            throws NoRefreshTokenException {
        mediator.deleteActiveCredential();
        request.getSession().invalidate();
        Cookie cookie = new Cookie("drive", "");
        cookie.setMaxAge(0);
        response.addCookie(cookie);
        throw new NoRefreshTokenException();
    }
}