Home | History | Annotate | Download | only in app 
      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.app;
     18 
     19 import org.xmlpull.v1.XmlPullParser;
     20 import org.xmlpull.v1.XmlPullParserException;
     21 
     22 import android.content.Intent;
     23 import android.content.pm.ActivityInfo;
     24 import android.content.pm.PackageManager;
     25 import android.content.res.XmlResourceParser;
     26 import android.os.Bundle;
     27 import android.util.AttributeSet;
     28 import android.util.Xml;
     29 
     30 import com.android.internal.util.XmlUtils;
     31 
     32 import java.io.IOException;
     33 
     34 /**
     35  * Stub activity that launches another activity (and then finishes itself)
     36  * based on information in its component's manifest meta-data.  This is a
     37  * simple way to implement an alias-like mechanism.
     38  *
     39  * To use this activity, you should include in the manifest for the associated
     40  * component an entry named "android.app.alias".  It is a reference to an XML
     41  * resource describing an intent that launches the real application.
     42  */
     43 public class AliasActivity extends Activity {
     44     /**
     45      * This is the name under which you should store in your component the
     46      * meta-data information about the alias.  It is a reference to an XML
     47      * resource describing an intent that launches the real application.
     48      * {@hide}
     49      */
     50     public final String ALIAS_META_DATA = "android.app.alias";
     51 
     52     @Override
     53     protected void onCreate(Bundle savedInstanceState) {
     54         super.onCreate(savedInstanceState);
     55 
     56         XmlResourceParser parser = null;
     57         try {
     58             ActivityInfo ai = getPackageManager().getActivityInfo(
     59                     getComponentName(), PackageManager.GET_META_DATA);
     60             parser = ai.loadXmlMetaData(getPackageManager(),
     61                     ALIAS_META_DATA);
     62             if (parser == null) {
     63                 throw new RuntimeException("Alias requires a meta-data field "
     64                         + ALIAS_META_DATA);
     65             }
     66 
     67             Intent intent = parseAlias(parser);
     68             if (intent == null) {
     69                 throw new RuntimeException(
     70                         "No <intent> tag found in alias description");
     71             }
     72 
     73             startActivity(intent);
     74             finish();
     75 
     76         } catch (PackageManager.NameNotFoundException e) {
     77             throw new RuntimeException("Error parsing alias", e);
     78         } catch (XmlPullParserException e) {
     79             throw new RuntimeException("Error parsing alias", e);
     80         } catch (IOException e) {
     81             throw new RuntimeException("Error parsing alias", e);
     82         } finally {
     83             if (parser != null) parser.close();
     84         }
     85     }
     86 
     87     private Intent parseAlias(XmlPullParser parser)
     88             throws XmlPullParserException, IOException {
     89         AttributeSet attrs = Xml.asAttributeSet(parser);
     90 
     91         Intent intent = null;
     92 
     93         int type;
     94         while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
     95                 && type != XmlPullParser.START_TAG) {
     96         }
     97 
     98         String nodeName = parser.getName();
     99         if (!"alias".equals(nodeName)) {
    100             throw new RuntimeException(
    101                     "Alias meta-data must start with <alias> tag; found"
    102                     + nodeName + " at " + parser.getPositionDescription());
    103         }
    104 
    105         int outerDepth = parser.getDepth();
    106         while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
    107                && (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
    108             if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
    109                 continue;
    110             }
    111 
    112             nodeName = parser.getName();
    113             if ("intent".equals(nodeName)) {
    114                 Intent gotIntent = Intent.parseIntent(getResources(), parser, attrs);
    115                 if (intent == null) intent = gotIntent;
    116             } else {
    117                 XmlUtils.skipCurrentTag(parser);
    118             }
    119         }
    120 
    121         return intent;
    122     }
    123 
    124 }
    125