Android 4.1.2为通知栏添加wifi开关

在Android 4.1.2系统中，默认的通知栏上有个WIFI的选项，点击该选项系统会弹出settings应用的wifi设置页面，而后我们进行wifi的连接，并且可以正常上网。理论上在之后的使用中我们可以一直打开着wifi，而不用再次进入wifi设置页面，但偶尔还是需要关闭wifi，比如为了省电。此时当我们要关闭的时候，还是需要进入wifi设置页面。所以为了方便期间，可以通过修改SystemUI的通知栏，zaiwifi一栏添加一个wifi的开关，这样就可以很方便的打开和关闭wifi了。
为实现此功能，我们需要修改两个地方，首先需要在frameworks/base/packages/SystemUI/res/layout/system_bar_settings_view.xml中添加wifi栏上的开关按钮：

<!-- Network -->
     <LinearLayout
             android:id="@+id/network"
             style="@style/StatusBarPanelSettingsRow"
             >
         <ImageView
                 android:id="@+id/network_icon"
                 style="@style/StatusBarPanelSettingsIcon"
                 android:src="@drawable/ic_sysbar_wifi_on"
                 />
         <TextView
                 android:id="@+id/network_label"
                 style="@style/StatusBarPanelSettingsContents"
                 android:text="@string/status_bar_settings_wifi_butt
                 />

                 android:id="@+id/network_checkbox"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_gravity="center_vertical"
                 android:layout_marginRight="5dp

通过添加名为network_checkbox的开关按钮，就可以在wifi设置栏上显示一个开关了。接下来需要添加对此开关的操作代码，我们需要修改frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/tablet/SettingsView.java

import android.content.BroadcastReceiver;
import android.net.wifi.WifiManager;
import android.content.IntentFilter;
public class SettingsView extends LinearLayout implements View.OnClickListener {
    static final String TAG = "SettingsView";

    AirplaneModeController mAirplane;
    AutoRotateController mRotate;
    BrightnessController mBrightness;
    DoNotDisturbController mDoNotDisturb;
    View mRotationLockContainer;
    View mRotationLockSeparator;
    private CompoundButton mNetworkCheckbox;
    private BroadcastReceiver WifiStateReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)) {
                WifiManager wifiManager =
                    (WifiManager)context.getSystemService(Context.WIFI_SERVICE);
                int wifiState = wifiManager.getWifiState();
                if (wifiState == wifiManager.WIFI_STATE_ENABLED)
                    mNetworkCheckbox.setChecked(true);
                else if (wifiState == wifiManager.WIFI_STATE_DISABLED) {
                    mNetworkCheckbox.setChecked(false);
                }
            }
        }
    };
    private CompoundButton.OnCheckedChangeListener NetworkCheckboxHandler =
        new CompoundButton.OnCheckedChangeListener() {
        public void onCheckedChanged(CompoundButton view, boolean checked) {
            WifiManager wifiManager =
                (WifiManager)getContext().getSystemService(Context.WIFI_SERVICE);
            int wifiState = wifiManager.getWifiState();
            if (checked) {
                if (wifiState == wifiManager.WIFI_STATE_DISABLED) {
                    Slog.d(TAG, "WIFI enable\n");
                    wifiManager.setWifiEnabled(true);
                }
            } else {
                if (wifiState == wifiManager.WIFI_STATE_ENABLED) {
                    Slog.d(TAG, "WIFI disable\n");
                    wifiManager.setWifiEnabled(false);
                }
            }
        }
    };

    public SettingsView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public SettingsView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();

        final Context context = getContext();

        mAirplane = new AirplaneModeController(context,
                (CompoundButton)findViewById(R.id.airplane_checkbox));

        findViewById(R.id.network).setOnClickListener(this);
        mNetworkCheckbox = (CompoundButton)findViewById(R.id.network_checkbox);
        mNetworkCheckbox.setOnCheckedChangeListener(NetworkCheckboxHandler);

        WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
        IntentFilter wifiIntentFilter = new IntentFilter();
        wifiIntentFilter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
        context.registerReceiver(WifiStateReceiver, wifiIntentFilter);

        mRotationLockContainer = findViewById(R.id.rotate);
        mRotationLockSeparator = findViewById(R.id.rotate_separator);
        mRotate = new AutoRotateController(context,
                (CompoundButton)findViewById(R.id.rotate_checkbox),
                new AutoRotateController.RotationLockCallbacks() {
                    @Override
                    public void setRotationLockControlVisibility(boolean show) {
                        mRotationLockContainer.setVisibility(show ? View.VISIBLE : View.GONE);
                        mRotationLockSeparator.setVisibility(show ? View.VISIBLE : View.GONE);
                    }
                });

        mBrightness = new BrightnessController(context,
                (ToggleSlider)findViewById(R.id.brightness));
        mDoNotDisturb = new DoNotDisturbController(context,
                (CompoundButton)findViewById(R.id.do_not_disturb_checkbox));
        findViewById(R.id.settings).setOnClickListener(this);
    }

这里说明一下，主要改动是在onFinishInflate函数中获取到开关控件network_checkbox，而后为其添加setOnCheckedChangeListener以处理用户的点击事件，在点击回调里，通过wifiManager.setWifiEnabled函数打开和关闭wifi。而注册一个WifiStateReceiver主要是用来同步wifi的开关状态的，因为如果用户在Settings里面打开了wifi，那相应的状态栏中的wifi开关状态也应该跟着同步变化。
修改后效果如下：