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Android example source code file (AliasActivity.java)

This example Android source code file (AliasActivity.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

activityinfo, alias_meta_data, aliasactivity, android, attributeset, content, error, intent, ioexception, no, os, override, runtimeexception, string, util, utilities, utils, xmlpullparserexception, xmlresourceparser

The AliasActivity.java Android example source code

/*
 * 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;
    }
    
}

Other Android examples (source code examples)

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