实现流程图如下：  源码路径，https://download.csdn.net/download/gaoyuekang/11594258。

详细描述：

属于系统服务，存放目录在/system/app 下 。本服务，Persisent app拉起。下面是所有的源码.

关键代码如下：

1. 启动：SplitScreenApplication.java

package com.xxx.splitscreen;

import android.app.Application;
import android.util.Log;
import android.content.Intent;
import android.content.ComponentName;
import android.content.Context;
import android.content.ServiceConnection;
import android.os.UserHandle;
import android.os.Binder;
import android.os.IBinder;
import android.os.Parcel;
import android.os.RemoteException;

public class SplitScreenApplication extends Application {
    private static final String TAG = Utils.TAG +" Application";

    @Override
    public void onCreate() {
        super.onCreate();
        Log.d(TAG, "start");

        new Thread(new Runnable() {
            @Override
            public void run() {
                int time = 0;
                Intent intent = new Intent();
                intent.setComponent(new ComponentName("com.xxx.splitscreen",
                        "com.xxx.splitscreen.SplitScreenService"));
                while (!getApplicationContext().bindService(intent, connection,
                        Context.BIND_AUTO_CREATE)) {
                    try {
                        final int ms = 1000;
                        Thread.sleep(ms);
                    } catch (InterruptedException ie) {
                        ie.printStackTrace();
                    }
                    time++;
                    Log.d(TAG, "bindSplitScreenService = " + time);
                }
            }
        }).start();
    }

    private final ServiceConnection connection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            Log.d(TAG, "** onServiceConnected**");

        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {

            Log.d(TAG, "** onServiceDisconnected**");
        }
    };

}

2. SS服务代码：SplitScreenService.java

package com.xxx.splitscreen;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.ComponentName;
import android.database.ContentObserver;
import android.os.Handler;
import android.os.IBinder;
import android.os.ServiceManager;
import android.provider.Settings;
import android.util.Log;
import android.app.TaskStackListener;

public class SplitScreenService extends Service {

    private static final String TAG = Utils.TAG + " Service";

    private Utils mUtil = null;
    private SplitScreenController mController = null;
    private SplitScreenManager mManager = null;
    private SplitScreenListener mListener = null;

    @Override
    public IBinder onBind(Intent intent) {
        Log.d(TAG, "receive bind request");
        return mManager;
    }

    @Override
    public void onCreate() {
        // mUtil 工具类
        mUtil = Utils.getInstance();
        mUtil.init(getBaseContext());
        
        // mController 控制类
        mController = SplitScreenController.getInstance();
        mController.init(getBaseContext());
        
        // mListener 监听类
        mListener = new SplitScreenListener(getBaseContext());
        mListener.register();

        // mManger 对外ibinder类
        mManager = new SplitScreenManager();
        ServiceManager.addService("SPLITSCREEN", mManager);

        // 这行代码是实际处理业务时逻辑用的,不需要care        mController.sendHandlerDelayMessage(Utils.HANDLE_MSG_SPLITSCREEN_START_DELAY, 100);
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        if (mListener != null)
            mListener.unregister();

        if (mController != null)
            mController.clearAllCallbacks();

        super.onDestroy();
    }
}

3. 控制代码：SplitScreenController.java

package com.xxx.splitscreen;

import static android.app.WindowConfiguration.WINDOWING_MODE_SPLIT_SCREEN_PRIMARY;
import static android.app.ActivityManager.SPLIT_SCREEN_CREATE_MODE_BOTTOM_OR_RIGHT;
import android.app.ActivityManager;
import android.app.ActivityOptions;
import android.app.IActivityManager;
import android.app.WindowConfiguration;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.Rect;
import android.os.Message;
import android.os.RemoteException;
import android.os.UserHandle;
import android.provider.Settings;
import android.util.Log;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.WindowManager;

import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

public class SplitScreenController {
    private static final String TAG = Utils.TAG + " Controller";

    // 分屏默认launch的app包名和ACT名
    private String mLaunchPkgName = Utils.DEFAULT_PKG_NAME;
    private String mLaunchActName = Utils.DEFAULT_ACT_NAME;

    // 乱七八糟的用于实际业务处理的tag值
    private boolean mHasSetDismissState = false;
    private boolean mSoftKeyboardState = false;
    private boolean mDialogShowing = false;      // flag for dialog show/dismiss
    private boolean mButtonDoing = false;        // flag for float button clicked delay
    private boolean mInVideoFullScreen = false;  // flag for bt-video in/out full screen
    private boolean mIsPopupActivity = false;    // flag for popup activity been created
    private boolean mWindowShowing = false;      // flag for window layout show/dismiss

    // 回调集合
    private Set<ISSCallBack> mCallbacks = new HashSet<ISSCallBack>();

    private int mSplitScreenStatus = Utils.STATUS_DEFAULT;

    private Utils mUtil = null;
    private Context mContext = null;
    private IActivityManager mAm = null;
    private WindowManager mWinMgr = null;
    public FloatButton mFloatButton = null;
    public SplitScreen mSplitScreen = null;

    private static class SingletonInst {
        private static final SplitScreenController INST = new SplitScreenController();
    }

    private SplitScreenController() {
    }

    public static SplitScreenController getInstance() {
        return SingletonInst.INST;
    }

    /
    //>> SplitScreenController initialization
    /

    public void init(Context context) {
        mContext = context;
        mUtil = Utils.getInstance();
        mAm = ActivityManager.getService();
        mWinMgr = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);

        mFloatButton = new FloatButton(mContext);
        mWinMgr.addView(mFloatButton, mFloatButton.layoutParams());

        mSplitScreen = new SplitScreen(mContext);
    }


    /
    //>> FloatButton clicked onFloatButtonClicked
    /

    public void onFloatButtonClicked(MotionEvent event) {
        if (mButtonDoing)
            return;

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mFloatButton.selectModeChange();
                break;
            case MotionEvent.ACTION_UP:
                mFloatButton.normalModeChange();
                if (Utils.STATUS_SHOW != mSplitScreenStatus) {
                    showSplitScreen();
                } else {
                    hideSplitScreen();
                }
                break;
            default:
                break;
        }
    }

    /
    //>> SplitScreen started/restarted
    /

    public void startSplitScreen() {
        mSplitScreen.start();
    }


    /
    //>> TaskStackListener onTaskStackChanged onTaskCreated onTaskMovedToFront
    /

    public void onTaskStackChanged() {
        Log.d(TAG, "onTaskStackChanged");

        ActivityManager.RunningTaskInfo topTask = mUtil.getTopTaskInfo();
        showOrHideFloatButton(topTask);
    }

    public void onTaskCreated(int taskId, ComponentName componentName) {
        Log.d(TAG, "onTaskCreated: " + componentName.toString());
        if (componentName.getPackageName().equals(mLaunchPkgN