content: /*
   * Copyright (C) 2007 The Android Open Source Project
   *
   * 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 android.app;
  
  import org.xmlpull.v1.XmlPullParser;
  import org.xmlpull.v1.XmlPullParserException;
  
  import android.content.Intent;
  import android.content.pm.ActivityInfo;
  import android.content.pm.PackageManager;
  import android.content.res.XmlResourceParser;
  import android.os.Bundle;
  import android.util.AttributeSet;
  import android.util.Xml;
  
  import com.android.internal.util.XmlUtils;
  
  import java.io.IOException;
  
  /**
   * Stub activity that launches another activity (and then finishes itself)
   * based on information in its component's manifest meta-data.  This is a
   * simple way to implement an alias-like mechanism.
   * 
   * To use this activity, you should include in the manifest for the associated
   * component an entry named "android.app.alias".  It is a reference to an XML
   * resource describing an intent that launches the real application.
   */
  public class AliasActivity extends Activity {
      /**
       * This is the name under which you should store in your component the
       * meta-data information about the alias.  It is a reference to an XML
       * resource describing an intent that launches the real application.
       * {@hide}
       */
      public final String ALIAS_META_DATA = "android.app.alias";
      
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          
          XmlResourceParser parser = null;
          try {
              ActivityInfo ai = getPackageManager().getActivityInfo(
                      getComponentName(), PackageManager.GET_META_DATA);
              parser = ai.loadXmlMetaData(getPackageManager(),
                      ALIAS_META_DATA);
              if (parser == null) {
                  throw new RuntimeException("Alias requires a meta-data field "
                          + ALIAS_META_DATA);
              }
              
              Intent intent = parseAlias(parser);
              if (intent == null) {
                  throw new RuntimeException(
                          "No <intent> tag found in alias description");
              }
              
              startActivity(intent);
              finish();
              
          } catch (PackageManager.NameNotFoundException e) {
              throw new RuntimeException("Error parsing alias", e);
          } catch (XmlPullParserException e) {
              throw new RuntimeException("Error parsing alias", e);
          } catch (IOException e) {
              throw new RuntimeException("Error parsing alias", e);
          } finally {
              if (parser != null) parser.close();
          }
      }
  
      private Intent parseAlias(XmlPullParser parser)
              throws XmlPullParserException, IOException {
          AttributeSet attrs = Xml.asAttributeSet(parser);
          
          Intent intent = null;
          
          int type;
          while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                  && type != XmlPullParser.START_TAG) {
          }
          
          String nodeName = parser.getName();
          if (!"alias".equals(nodeName)) {
              throw new RuntimeException(
                      "Alias meta-data must start with <alias> tag; found"
                      + nodeName + " at " + parser.getPositionDescription());
          }
          
          int outerDepth = parser.getDepth();
          while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                 && (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
              if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
                  continue;
              }
  
              nodeName = parser.getName();
              if ("intent".equals(nodeName)) {
                  Intent gotIntent = Intent.parseIntent(getResources(), parser, attrs);
                  if (intent == null) intent = gotIntent;
              } else {
                  XmlUtils.skipCurrentTag(parser);
              }
          }
          
          return intent;
      }
      
  }
  