Andriod:缓存

在安卓开发中,应用会有清理缓存的功能.但是清理缓存这个功能,安卓里面是有相应的方法,不过google设置成了hide,不能直接调用.

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PackageManager的getPackageSizeInfo这个函数，google是不对外公开的，我们需要使用发射来调用这个函数，在该方法的内部回调了

onGetStatsCompleted(PackageStats pStats, boolean succeeded)这个方法，通过该方法的pStats参数可以得到应用的缓存，数据缓存，代码容量缓存，在这过程中还需要用到系统的aidl文件IPackageStatsObserver：

/**** 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 android.content.pm;import android.content.pm.PackageStats;/** * API for package data change related callbacks from the Package Manager. * Some usage scenarios include deletion of cache directory, generate * statistics related to code, data, cache usage(TODO) * {@hide} */oneway interface IPackageStatsObserver {    void onGetStatsCompleted(in PackageStats pStats, boolean succeeded);}

PackageStats:

/* * Copyright (C) 2008 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.content.pm;import android.os.Parcel;import android.os.Parcelable;import android.os.UserHandle;/** * implementation of PackageStats associated with a * application package. */public class PackageStats implements Parcelable {    /** Name of the package to which this stats applies. */    public String packageName;    /** @hide */    public int userHandle;    /** Size of the code (e.g., APK) */    public long codeSize;    /**     * Size of the internal data size for the application. (e.g.,     * /data/data/<app>)     */    public long dataSize;    /** Size of cache used by the application. (e.g., /data/data/<app>/cache) */    public long cacheSize;    /**     * Size of the secure container on external storage holding the     * application's code.     */    public long externalCodeSize;    /**     * Size of the external data used by the application (e.g.,     * <sdcard>/Android/data/<app>)     */    public long externalDataSize;    /**     * Size of the external cache used by the application (i.e., on the SD     * card). If this is a subdirectory of the data directory, this size will be     * subtracted out of the external data size.     */    public long externalCacheSize;    /** Size of the external media size used by the application. */    public long externalMediaSize;    /** Size of the package's OBBs placed on external media. */    public long externalObbSize;    public static final Parcelable.Creator<PackageStats> CREATOR            = new Parcelable.Creator<PackageStats>() {        public PackageStats createFromParcel(Parcel in) {            return new PackageStats(in);        }        public PackageStats[] newArray(int size) {            return new PackageStats[size];        }    };    public String toString() {        final StringBuilder sb = new StringBuilder("PackageStats{");        sb.append(Integer.toHexString(System.identityHashCode(this)));        sb.append(" ");        sb.append(packageName);        if (codeSize != 0) {            sb.append(" code=");            sb.append(codeSize);        }        if (dataSize != 0) {            sb.append(" data=");            sb.append(dataSize);        }        if (cacheSize != 0) {            sb.append(" cache=");            sb.append(cacheSize);        }        if (externalCodeSize != 0) {            sb.append(" extCode=");            sb.append(externalCodeSize);        }        if (externalDataSize != 0) {            sb.append(" extData=");            sb.append(externalDataSize);        }        if (externalCacheSize != 0) {            sb.append(" extCache=");            sb.append(externalCacheSize);        }        if (externalMediaSize != 0) {            sb.append(" media=");            sb.append(externalMediaSize);        }        if (externalObbSize != 0) {            sb.append(" obb=");            sb.append(externalObbSize);        }        sb.append("}");        return sb.toString();    }    public PackageStats(String pkgName) {        packageName = pkgName;        userHandle = UserHandle.myUserId();    }    /** @hide */    public PackageStats(String pkgName, int userHandle) {        this.packageName = pkgName;        this.userHandle = userHandle;    }    public PackageStats(Parcel source) {        packageName = source.readString();        userHandle = source.readInt();        codeSize = source.readLong();        dataSize = source.readLong();        cacheSize = source.readLong();        externalCodeSize = source.readLong();        externalDataSize = source.readLong();        externalCacheSize = source.readLong();        externalMediaSize = source.readLong();        externalObbSize = source.readLong();    }    public PackageStats(PackageStats pStats) {        packageName = pStats.packageName;        userHandle = pStats.userHandle;        codeSize = pStats.codeSize;        dataSize = pStats.dataSize;        cacheSize = pStats.cacheSize;        externalCodeSize = pStats.externalCodeSize;        externalDataSize = pStats.externalDataSize;        externalCacheSize = pStats.externalCacheSize;        externalMediaSize = pStats.externalMediaSize;        externalObbSize = pStats.externalObbSize;    }    public int describeContents() {        return 0;    }    public void writeToParcel(Parcel dest, int parcelableFlags){        dest.writeString(packageName);        dest.writeInt(userHandle);        dest.writeLong(codeSize);        dest.writeLong(dataSize);        dest.writeLong(cacheSize);        dest.writeLong(externalCodeSize);        dest.writeLong(externalDataSize);        dest.writeLong(externalCacheSize);        dest.writeLong(externalMediaSize);        dest.writeLong(externalObbSize);    }}

//deleteApplicationCacheFiles

这是都是隐藏的,不能直接调用,,需要用到反射

 /**     * Attempts to delete the cache files associated with an application.     * Since this may take a little while, the result will     * be posted back to the given observer.  A deletion will fail if the calling context     * lacks the {@link android.Manifest.permission#DELETE_CACHE_FILES} permission, if the     * named package cannot be found, or if the named package is a "system package".     *     * @param packageName The name of the package to delete     * @param observer An observer callback to get notified when the cache file deletion     * is complete.     * {@link android.content.pm.IPackageDataObserver#onRemoveCompleted(String, boolean)}     * will be called when that happens.  observer may be null to indicate that     * no callback is desired.     *     * @hide     */    public abstract void deleteApplicationCacheFiles(String packageName,            IPackageDataObserver observer);

清理缓存有几种方法:

1.清除本地上的缓存,通过跌代找到要删除的文件和文件夹,删除就行

2.让用户自己清理,直接跳到设置页面:

            Intent intent = new Intent();       intent.setAction("android.settings.APPLICATION_DETAILS_SETTINGS");       intent.addCategory(Intent.CATEGORY_DEFAULT);        intent.setData(Uri.parse("package:"+你的包名);        startActivity(intent);

3.使用系统的方法来清理缓存:

//先获取到当前应用有没有缓存,并保存它的图标,包名等信息

private void getCache(final String packageName) {Method[] methods = PackageManager.class.getDeclaredMethods();for (Method method : methods) {    if ("getPackageSizeInfo".equals(method.getName())) {try {method.invoke(pm, packageName,new IPackageStatsObserver.Stub() {@Overridepublic void onGetStatsCompleted(PackageStats pStats, boolean succeeded)throws RemoteException {    long cacheSize = pStats.cacheSize; // System.out.println("缓存大小" + cacheSize);                    if (cacheSize > 0) {// 有缓存                      cacheInfo = new AppCacheinfo();      cacheInfo.size = cacheSize;//System.out.println(cacheInfo.count);cacheInfo.appPackName = packageName;try {                          cacheInfo.appIcon = pm.getApplicationInfo(packageName, 0).loadIcon(pm);  cacheInfo.appName = pm.getApplicationInfo(packageName, 0).loadLabel(pm).toString();} catch (NameNotFoundException e) {e.printStackTrace();}}}});} catch (Exception e) {e.printStackTrace();}} }}

//开始清理缓存

//pm.deleteApplicationCacheFiles(info.packName,new ClearCacheObserver());//Method[]  methods = PackageManager.class.getMethods();//for(Method method:methods){//if("deleteApplicationCacheFiles".equals(method.getName())){//try {//method.invoke(pm, info.packName,new ClearCacheObserver());//Toast.makeText(getActivity(), "清理成功", 0).show();//} catch (Exception e) {//e.printStackTrace();//Toast.makeText(getActivity(), "清理失败", 0).show();//}//return;//}//}

也可以这样

让应用申请一个很大的内存的空间.

//告知服务器,我们要申请一个很大的内存空间Method[] methods = PackageManager.class.getDeclaredMethods();for(Method method:methods){if("freeStorageAndNotify".equals(method.getName())){try {method.invoke(pm, Long.MAX_VALUE,new IPackageDataObserver.Stub(){@Overridepublic void onRemoveCompleted(String packageName,boolean succeeded) throws RemoteException {}});} catch (Exception e) {e.printStackTrace();}}}