Android example source code file (AttributeCache.java)

This example Android source code file (AttributeCache.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

android, attributecache, configuration, content, context, entry, hashmap, package, sparsearray, typedarray, util, utilities, utils, weakhashmap

The AttributeCache.java Android example source code

/*
**
** Copyright 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 com.android.server;

import android.content.Context;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.util.SparseArray;

import java.util.HashMap;
import java.util.WeakHashMap;

/**
 * TODO: This should be better integrated into the system so it doesn't need
 * special calls from the activity manager to clear it.
 */
public final class AttributeCache {
    private static AttributeCache sInstance = null;
    
    private final Context mContext;
    private final WeakHashMap<String, Package> mPackages =
            new WeakHashMap<String, Package>();
    private final Configuration mConfiguration = new Configuration();
    
    public final static class Package {
        public final Context context;
        private final SparseArray<HashMap mMap
                = new SparseArray<HashMap();
        
        public Package(Context c) {
            context = c;
        }
    }
    
    public final static class Entry {
        public final Context context;
        public final TypedArray array;
        
        public Entry(Context c, TypedArray ta) {
            context = c;
            array = ta;
        }
    }
    
    public static void init(Context context) {
        if (sInstance == null) {
            sInstance = new AttributeCache(context);
        }
    }
    
    public static AttributeCache instance() {
        return sInstance;
    }
    
    public AttributeCache(Context context) {
        mContext = context;
    }
    
    public void removePackage(String packageName) {
        synchronized (this) {
            mPackages.remove(packageName);
        }
    }
    
    public void updateConfiguration(Configuration config) {
        synchronized (this) {
            int changes = mConfiguration.updateFrom(config);
            if ((changes & ~(ActivityInfo.CONFIG_FONT_SCALE |
                    ActivityInfo.CONFIG_KEYBOARD_HIDDEN |
                    ActivityInfo.CONFIG_ORIENTATION)) != 0) {
                // The configurations being masked out are ones that commonly
                // change so we don't want flushing the cache... all others
                // will flush the cache.
                mPackages.clear();
            }
        }
    }
    
    public Entry get(String packageName, int resId, int[] styleable) {
        synchronized (this) {
            Package pkg = mPackages.get(packageName);
            HashMap<int[], Entry> map = null;
            Entry ent = null;
            if (pkg != null) {
                map = pkg.mMap.get(resId);
                if (map != null) {
                    ent = map.get(styleable);
                    if (ent != null) {
                        return ent;
                    }
                }
            } else {
                Context context;
                try {
                    context = mContext.createPackageContext(packageName, 0);
                    if (context == null) {
                        return null;
                    }
                } catch (PackageManager.NameNotFoundException e) {
                    return null;
                }
                pkg = new Package(context);
                mPackages.put(packageName, pkg);
            }
            
            if (map == null) {
                map = new HashMap<int[], Entry>();
                pkg.mMap.put(resId, map);
            }
            
            try {
                ent = new Entry(pkg.context,
                        pkg.context.obtainStyledAttributes(resId, styleable));
                map.put(styleable, ent);
            } catch (Resources.NotFoundException e) {
                return null;
            }
            
            return ent;
        }
    }
}