每日学习总结<二> 2015-9-1

Android：

     知识点：

• 子线程中无法更新UI，因为UI是线程不安全的。
  • Android的UI单线程模式：
    1. 不能阻塞UI线程；
    2. 不能从UI线程的外部访问Android UI toolkit。 
    3. 需要更新UI可以使用Handler传值。具体使用方式如学习总结五：

 

实践项目：

一键清理内存

功能：实现Android中，结束当前活跃APP进程，释放内存的Demo。

 

知识点：

• ActivityManager的用法等等

public String getMemoryState(Context context) {

        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        ActivityManager.MemoryInfo info = new ActivityManager.MemoryInfo();
        activityManager.getMemoryInfo(info);
//                Log.e(MainActivity.TAG, "剩余内存" + (info.availMem >> 100000) + "M");
        Log.e(MainActivity.TAG, "是否处于低内存：" + info.lowMemory);
        Log.e(MainActivity.TAG, "threshold: " + info.threshold);
        memoryValueLong = (info.availMem / 1048576);
        memoryValueString = Long.toString(memoryValueLong);
        Log.e(MainActivity.TAG, "可用内存: " + memoryValueString + "MB");

        return memoryValueString;
    }

    public long getMemoryValueLong(Context context) {
        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        ActivityManager.MemoryInfo info = new ActivityManager.MemoryInfo();
        activityManager.getMemoryInfo(info);
//                Log.e(MainActivity.TAG, "剩余内存" + (info.availMem >> 100000) + "M");
        Log.e(MainActivity.TAG, "是否处于低内存：" + info.lowMemory);
        Log.e(MainActivity.TAG, "threshold: " + info.threshold);
        memoryValueLong = (info.availMem / 1048576);
        return memoryValueLong;
    }

    public void killProcess() {
        ActivityManager activityManager2 = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> infoList = activityManager2.getRunningAppProcesses();
        List<ActivityManager.RunningServiceInfo> serviceInfoList = activityManager2.getRunningServices(200);
        long beforeMem = getMemoryValueLong(MainActivity.this);
        Log.d(TAG, "-----------before memory info : " + beforeMem);
        int count = 0;
        if (infoList != null) {
            for (int i = 0; i < infoList.size(); ++i) {
                ActivityManager.RunningAppProcessInfo appProcessInfo = infoList.get(i);
                Log.e(TAG, "process name : " + appProcessInfo.processName);
                //importance 该进程的重要程度  分为几个级别，数值越低就越重要。
                Log.e(TAG, "importance : " + appProcessInfo.importance);
                // 一般数值大于RunningAppProcessInfo.IMPORTANCE_SERVICE的进程都长时间没用或者空进程了
                // 一般数值大于RunningAppProcessInfo.IMPORTANCE_VISIBLE的进程都是非可见进程，也就是在后台运行着
                if (appProcessInfo.importance > ActivityManager.RunningAppProcessInfo.IMPORTANCE_SERVICE) {
                    String[] pkgList = appProcessInfo.pkgList;
                    for (int j = 0; j < pkgList.length; ++j) {
                        Log.e(MainActivity.TAG, "Killed package name: " + pkgList[j]);
                        activityManager2.killBackgroundProcesses(pkgList[j]);
                        count++;

                    }
                }

                long clearAfeterMemoryState = getMemoryValueLong(MainActivity.this);
                Toast.makeText(MainActivity.this, "已清理内存：" + Long.toString(beforeMem - clearAfeterMemoryState) + " 当前内存为：  " + Long.toString(clearAfeterMemoryState), Toast.LENGTH_SHORT).show();
            }


        }
    }

• 创建快捷方式：

 

private void addShortCut() {
    Log.e(MainActivity.TAG, "====addShortCut()====");

    Intent shortCutIntent = new Intent("com.android.launcher.action.INSTALL_SHORTCUT");
    //快捷方式名称
    shortCutIntent.putExtra(Intent.EXTRA_SHORTCUT_NAME, getString(R.string.app_name));
    shortCutIntent.putExtra("duplicate", false);

    ComponentName componentName = new ComponentName(this.getPackageName(), "." + this.getLocalClassName());
    shortCutIntent.putExtra(Intent.EXTRA_SHORTCUT_NAME, new Intent(Intent.ACTION_MAIN).setComponent(componentName));

    //快捷方式的图标
    Intent.ShortcutIconResource iconResource = new Intent.ShortcutIconResource().fromContext(this, R.drawable.ic_launcher);
    shortCutIntent.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, iconResource);
    sendBroadcast(shortCutIntent);

}