ContentObser实例_contentobser onchange selfchange-优快云博客

本文链接：https://blog.youkuaiyun.com/solarsaber/article/details/72730126

本文介绍了如何在Android中使用ContentObserver来监听特定系统设置的变化，例如当前媒体播放工具和电池百分比显示设置。通过具体代码示例展示了如何注册及取消注册观察者，并在设置发生变化时触发回调。

  
 public static final String CURRENT_MEDIA_TOOL = "current_media_tool";
 private void registerObserver() {
        Uri uri = Settings.System.getUriFor(MusicManager.CURRENT_MEDIA_TOOL);
        mContext.getContentResolver().registerContentObserver(uri, false,
                mObserver);
    }

    private ContentObserver mObserver = new ContentObserver(null) {

        @Override
        public void onChange(boolean selfChange, Uri uri) {
            super.onChange(selfChange, uri);

            String uriStr = uri.getLastPathSegment();
            if (MusicManager.CURRENT_MEDIA_TOOL.equals(uriStr)) {
                String currentMediaTool = Settings.System.getString(
                        mContext.getContentResolver(),
                        MusicManager.CURRENT_MEDIA_TOOL);
                LogUtil.d(TAG, "play media changed! currentMediaTool is:"
                        + currentMediaTool);
                switch (currentMediaTool) {
                    case MusicManager.CHEYUEBAO:
                        registerCYBMusic();
                        registerCYBFm();
                        break;
                    case MusicManager.KUWO:
                        registerKuWoMusic();
                        break;
                }
            }
        }

    };

//不用的时候 注意移除 
     mContext.getContentResolver().unregisterContentObserver(mObserver);
调用的地方
 public static final void setCurrentMedia(Context ctx, String str) {
        LogUtil.d(TAG, "setCurrentMedia: : " + str);
        Settings.System.putString(ctx.getContentResolver(), CURRENT_MEDIA_TOOL,
                str);
    }

只要设置入的  key值有变化就会自动调用 oberser的 onChange方法

实例二、电池百分比控制部分

       mContext.getContentResolver().registerContentObserver(
                    Settings.Secure.getUriFor(Settings.Secure.BATTERY_PERCENTAGE), true,
                    mBatteryPercentageObserver);
final private ContentObserver mBatteryPercentageObserver = new ContentObserver(new Handler()) {
    @Override
    public void onChange(boolean selfChange) {
       final boolean enable = Settings.Secure.getInt(mContext.getContentResolver(),                
         Settings.Secure.BATTERY_PERCENTAGE, 0) != 0;        
   mBatteryLevel.setVisibility(enable ? View.VISIBLE : View.GONE);
        final SignalClusterView mSignalCluster =
                (SignalClusterView) mStatusBarView.findViewById(R.id.signal_cluster);
   mKeyguardStatusBar.setBatteryPercentageVisibility(enable);
    }
};

状态值改变的地方

Settings.Secure.putInt(mContext.getContentResolver(),
      Settings.Secure.BATTERY_PERCENTAGE, state);