98利用反射清理应用程序的缓存以及清理所有应用程序的缓存

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当使用缓存得到单个应用程序的缓存之后，查看源码，得到清除缓存的方法，同样，这里也需要使用反射区清理，当完成后，提示我们需要添加权限：

<uses-permission android:name="android.permission.DELETE_CACHE_FILES"/>

但是当我们保存的时候，发现这条权限居然报错了，意思是：这个权限是授权给系统程序的，所以我们的程序不能使用清楚缓存的功能，当单击清除缓存的功能的时候，弹出到设置界面的清楚缓存的功能。

清理全部的缓存的思路是：

利用了系统的BUG，当系统内存不足的时候，系统会回收应用程序的缓存，我们可以发送信息给系统，告诉系统我们需要Integer.MAX_VALUE的内存空间。

 /**     * Free storage by deleting LRU sorted list of cache files across     * all applications. If the currently available free storage     * on the device is greater than or equal to the requested     * free storage, no cache files are cleared. If the currently     * available storage on the device is less than the requested     * free storage, some or all of the cache files across     * all applications are deleted (based on last accessed time)     * to increase the free storage space on the device to     * the requested value. There is no guarantee that clearing all     * the cache files from all applications will clear up     * enough storage to achieve the desired value.     * @param freeStorageSize The number of bytes of storage to be     * freed by the system. Say if freeStorageSize is XX,     * and the current free storage is YY,     * if XX is less than YY, just return. if not free XX-YY number     * of bytes if possible.     * @param observer call back used to notify when     * the operation is completed     *     * @hide     */    public abstract void freeStorageAndNotify(long freeStorageSize, IPackageDataObserver observer);

public void cleanAll(View view){///freeStorageAndNotifyMethod[] methods = PackageManager.class.getMethods();for(Method method:methods){if("freeStorageAndNotify".equals(method.getName())){try {method.invoke(pm, Integer.MAX_VALUE, new IPackageDataObserver.Stub() {@Overridepublic void onRemoveCompleted(String packageName,boolean succeeded) throws RemoteException {System.out.println(succeeded);}});} catch (Exception e) {e.printStackTrace();}return;}}}

最后，还要添加权限：

 <uses-permission android:name="android.permission.CLEAR_APP_CACHE"/>

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