In Android app can I listen for emails that arrive

2020-04-10 01:05发布

站内文章 / Android
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问题:

I am able to listen to SMS that arrives but after searching I can't find a way to listen for emails that arrive in GMAIL. I will take any way possible on any level of the OS. Thanks.

回答1:

See GmailContract of DashClock Widget for a working example.

Copy/pasting the source code below for reference just in case if the URL becomes unavailable.

/*
 * Copyright 2012 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.android.apps.dashclock.gmail;

import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.PermissionInfo;
import android.content.pm.ProviderInfo;
import android.net.Uri;
import android.text.TextUtils;

/**
 * <p>Contract for use with the Gmail content provider.</p>
 *
 * <p>Developers can use this content provider to display label information to the user.
 * <br/>
 * The label information includes:
 * <ul>
 *     <li>Label name</li>
 *     <li>Total number of conversations</li>
 *     <li>Number of unread conversations</li>
 *     <li>Label text color</li>
 *     <li>Label background color</li>
 * </ul></p>
 *
 * <p>This content provider is available in Gmail version 2.3.6 or newer for Froyo/Gingerbread
 * and version 4.0.5 and newer for Honeycomb and Ice Cream Sandwich</p>
 * <p>An application can query the
 * <a href="http://developer.android.com/reference/android/content/ContentResolver.html">
 *     Content Resolver</a> directly
 * (or use a <a href="http://developer.android.com/guide/topics/fundamentals/loaders.html"
 * target="_blank">Loader</a>)
 * to obtain a Cursor with information for all labels on an account</p>
 * <code>Cursor labelsCursor = getContentResolver().query(GmailContract.Labels.getLabelsUri(
 * selectedAccount), null, null, null, null);</code>
 */
public final class GmailContract {
    private GmailContract() {}

    /**
     * Permission required to access this {@link android.content.ContentProvider}
     */
    public static final String PERMISSION =
            "com.google.android.gm.permission.READ_CONTENT_PROVIDER";

    /**
     * Authority for the Gmail content provider.
     */
    public static final String AUTHORITY = "com.google.android.gm";

    static final String LABELS_PARAM = "/labels";
    static final String LABEL_PARAM = "/label/";
    static final String BASE_URI_STRING = "content://" + AUTHORITY;
    static final String PACKAGE = "com.google.android.gm";


    /**
     * Check if the installed Gmail app supports querying for label information.
     *
     * @param c an application Context
     * @return true if it's safe to make label API queries
     */
    public static boolean canReadLabels(Context c) {
        boolean supported = false;

        try {
            final PackageInfo info = c.getPackageManager().getPackageInfo(PACKAGE,
                    PackageManager.GET_PROVIDERS | PackageManager.GET_PERMISSIONS);
            boolean allowRead = false;
            if (info.permissions != null) {
                for (int i = 0, len = info.permissions.length; i < len; i++) {
                    final PermissionInfo perm = info.permissions[i];
                    if (PERMISSION.equals(perm.name)
                            && perm.protectionLevel < PermissionInfo.PROTECTION_SIGNATURE) {
                        allowRead = true;
                        break;
                    }
                }
            }
            if (allowRead && info.providers != null) {
                for (int i = 0, len = info.providers.length; i < len; i++) {
                    final ProviderInfo provider = info.providers[i];
                    if (AUTHORITY.equals(provider.authority) &&
                            TextUtils.equals(PERMISSION, provider.readPermission)) {
                        supported = true;
                    }
                }
            }
        } catch (NameNotFoundException e) {
            // Gmail app not found
        }
        return supported;
    }



    /**
     * Table containing label information.
     */
    public static final class Labels {
        /**
         * Label canonical names for default Gmail system labels.
         */
        public static final class LabelCanonicalNames {
            /**
             * Canonical name for the Inbox label
             */
            public static final String CANONICAL_NAME_INBOX = "^i";

            /**
             * Canonical name for the Priority Inbox label
             */
            public static final String CANONICAL_NAME_PRIORITY_INBOX = "^iim";

            /**
             * Canonical name for the Starred label
             */
            public static final String CANONICAL_NAME_STARRED = "^t";

            /**
             * Canonical name for the Sent label
             */
            public static final String CANONICAL_NAME_SENT = "^f";

            /**
             * Canonical name for the Drafts label
             */
            public static final String CANONICAL_NAME_DRAFTS = "^r";

            /**
             * Canonical name for the All Mail label
             */
            public static final String CANONICAL_NAME_ALL_MAIL = "^all";

            /**
             * Canonical name for the Spam label
             */
            public static final String CANONICAL_NAME_SPAM = "^s";

            /**
             * Canonical name for the Trash label
             */
            public static final String CANONICAL_NAME_TRASH = "^k";

            private LabelCanonicalNames() {}
        }

        /**
         * The MIME-type of uri providing a directory of
         * label items.
         */
        public static final String CONTENT_TYPE =
                "vnd.android.cursor.dir/vnd.com.google.android.gm.label";

        /**
         * The MIME-type of a label item.
         */
        public static final String CONTENT_ITEM_TYPE =
                "vnd.android.cursor.item/vnd.com.google.android.gm.label";

        /**
         * This string value is the canonical name of a label. Canonical names are not localized and
         * are not user-facing.
         *
         * <p>Type: TEXT</p>
         */
        public static final String CANONICAL_NAME = "canonicalName";
        /**
         * This string value is the user-visible name of a label. Names of system labels
         * (Inbox, Sent, Drafts...) are localized.
         *
         * <p>Type: TEXT</p>
         */
        public static final String NAME = "name";
        /**
         * This integer value is the number of conversations in this label.
         *
         * <p>Type: INTEGER</p>
         */
        public static final String NUM_CONVERSATIONS = "numConversations";
        /**
         * This integer value is the number of unread conversations in this label.
         *
         * <p>Type: INTEGER</p>
         */
        public static final String NUM_UNREAD_CONVERSATIONS = "numUnreadConversations";
        /**
         * This integer value is the label's foreground text color in 32-bit 0xAARRGGBB format.
         *
         * <p>Type: INTEGER</p>
         */
        public static final String TEXT_COLOR = "text_color";
        /**
         * This integer value is the label's background color in 32-bit 0xAARRGGBB format.
         *
         * <p>Type: INTEGER</p>
         */
        public static final String BACKGROUND_COLOR = "background_color";
        /**
         * This string column value is the uri that can be used in subsequent calls to
         * {@link android.content.ContentProvider#query()} to query for information on the single
         * label represented by this row.
         *
         * <p>Type: TEXT</p>
         */
        public static final String URI = "labelUri";

        /**
         * Returns a URI that, when queried, will return the list of labels for an
         * account.
         * <p>
         * To use the Labels API, an app must first find the email address of a
         * valid Gmail account to query for label information. The <a href=
         * "http://developer.android.com/reference/android/accounts/AccountManager.html"
         * target="_blank">AccountManager</a> can return this information (<a
         * href="https://developers.google.com/gmail/android">example</a>).
         * </p>
         *
         * @param account Name of a valid Google account.
         * @return The URL that can be queried to retrieve the the label list.
         */
        public static Uri getLabelsUri(String account) {
            return Uri.parse(BASE_URI_STRING + "/" + account + LABELS_PARAM);
        }

        private Labels() {}
    }
}

Hope this helps.



回答2:

Getting direct access the actual message is not possible to my knowledge. Best way I know is to use the Java MAIL for Android library (http://code.google.com/p/javamail-android/) and use the IMAP protocol to grab the message you are looking for.

But your actual question was about getting events from gmail. To get them, you can use a ContentObserver. First, declare you own subclass of ContentObserver:

class GmailContentObserver extends ContentObserver {

  public GmailContentObserver(Handler handler) {
    super(handler);
  }

  @Override
  public void onChange(boolean selfChange) {
    onChange(selfChange, null);
  }

  @Override
  public void onChange(boolean selfChange, Uri uri) {
    // This is where you will get your change notifications
    // for each received e-mails. This method will be called multiple times per
    // received e-mail. At least 3, but it depends on the way you register
    // your observer and on your gmail account set up (number of labels).
    // You will also get calls for other events. Remember that this method is
    // called for any change on the local gmail repository. Receiving an e-mail
    // is only one of many actions that will change this repository.
    Toast.makeText(MainActivity.this,"gmail event",Toast.LENGTH_LONG).show();
  }
}

Then register your ContentObserver:

  GmailContentObserver gco = new GmailContentObserver(new Handler());
  ContentResolver cr = getContentResolver();
  cr.registerContentObserver(Uri.parse("content://gmail-ls"),true,gco);

That's it!

Note that you should also unregister your observer when you don't need it anymore or when your application/service shuts down.

Note also the new Hanlder() when instantiating your observer. This will determine on which thread the onChange methods will be called. The thread on which the Handler object was created is the one on which onChange will be called (in my sample, you can't see this, but it is the UI thread, the one calling onCreate in my Activity).

When registering your observer, there are two parameters: the URI you want to observe and whether you want to observer the descendents. In the above sample code, you will get a notification for the URI content://gmail-ls but also for example for content://gmail-ls/foo@gmail.com, foo@gmail.com being your gmail account. And there are many more descendent URIs (especially labels). To get fewer events, you can register your observer for content://gmail-ls/foo@gmail.com and set the second parameter to false.

Given this mechanism, in theory if you wanted to observe changes on a given gmail Label, you could query for the Label id (see gmail api) and register the corresponding URI content://gmail-ls/foo@gmail.com/label/80, 80 being the label id. But for some reason this does not work.

Also check the gmail api already mentioned for code to determine if the installed gmail app has a content provider (depends on the version of gmail).



回答3:

If you want to get the content of the email, I would recommend using the Gmail REST API is very good (but you need to have user authorise within your app).

var url = 'https://www.googleapis.com/gmail/v1/users/me/messages?q=in%3Ainbox&'

We have used this in our app Speaking Email (shameless plug) which is a cordova app using javascript and the gmail API works very well for us.



标签： android api email gmail
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