悬浮窗

package com.bi.dialogactivity_xuanfuchuang.app;

import android.graphics.Color;
import android.graphics.PixelFormat;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.*;
import android.widget.LinearLayout;
import android.widget.TextView;


public class MainActivity extends ActionBarActivity {

    private LinearLayout ll;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        ll=new LinearLayout(this);
       ll.setBackgroundColor(Color.BLUE);
        Window window=getWindow();
        WindowManager.LayoutParams layoutParams = window.getAttributes();

        layoutParams.gravity= Gravity.CENTER;

        //x只有gravity设置了Left right之后才起作用
        //y只有gravity设置了top bottom之后才起作用
        layoutParams.x=10;
        layoutParams.y=10;
        layoutParams.width=WindowManager.LayoutParams.MATCH_PARENT;
        layoutParams.height=300;

        window.setAttributes(layoutParams);

        WindowManager manager=getWindowManager();
        WindowManager.LayoutParams lp=new WindowManager.LayoutParams();
        lp.gravity=Gravity.TOP|Gravity.LEFT;
        lp.x=100;
        lp.y=10;
        lp.width=200;
        lp.height=30;
        lp.type=WindowManager.LayoutParams.TYPE_SYSTEM_ALERT
                |WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;
        lp.flags=WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                |WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;//用户点击悬浮窗之外区域能传递事件
        //悬浮窗通过addView后如果悬浮窗可以获取焦点那么下层的activity将不能交互
        manager.addView(ll,lp);

    }
    //不重写此方法会导致回退键不能用
    @Override
    protected void onDestroy() {
        //释放悬浮窗
        WindowManager manager=getWindowManager();
        manager.removeViewImmediate(ll);
        super.onDestroy();
    }


}

上面是activity级别的悬浮窗  activity销毁的话  悬浮窗也会销毁

下面的是系统级别的不会销毁

package com.bi.xuanfuchuangxitong.app;

import android.graphics.PixelFormat;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.*;
import android.widget.ImageView;


public class MainActivity extends ActionBarActivity {


    private WindowManager.LayoutParams lp;
    private WindowManager manager;
    private static ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        manager = (WindowManager)getApplicationContext().getSystemService(WINDOW_SERVICE);
        //利用Application来创建ImageView避免activity退出导致的Context问题
        if(imageView!=null){
            manager.removeViewImmediate(imageView);
        }

        imageView = new ImageView(getApplicationContext());
        imageView.setImageResource(R.mipmap.ic_launcher);
        //设置触摸监听
        //建议使用匿名内部类来设置触摸的监听器
        imageView.setOnTouchListener(new View.OnTouchListener() {
            private float lastX, lastY;

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                boolean ret = false;
                int action = event.getAction();
                switch (action) {
                    case MotionEvent.ACTION_DOWN:
                        lastX = event.getRawX();
                        lastY = event.getRawY();
                        ret = true;
                        Log.d("ff", "-->" + action);
                        break;
                    case MotionEvent.ACTION_MOVE:
                        float cx = event.getRawX();
                        float cy = event.getRawY();
                        float ccx = cx - lastX;
                        float ccy = cy - lastY;

                        lp.x += ccx;
                        lp.y += ccy;
                        //更新悬浮窗
                        manager.updateViewLayout(imageView, lp);
                        lastY=cy;
                        lastX=cx;

                        Log.d("ff", "-->" + action);
                        break;
                    case MotionEvent.ACTION_UP:
                        Log.d("ff", "-->" + action);
                        break;
                }

                return ret;
            }
        });


        lp = new WindowManager.LayoutParams();
        //对于应用程序实用的系统类型
        //TYPE_SYSTEM_ALERT允许接收事件    TYPE_SYSTEM_OVERLAY只是悬浮
        lp.type=WindowManager.LayoutParams.TYPE_SYSTEM_ALERT
                |WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;
        lp.flags=WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                |WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;//用户点击悬浮窗之外区域能传递事件
        lp.gravity= Gravity.LEFT|Gravity.TOP;
        lp.x=300;
        lp.y=300;
        lp.width=WindowManager.LayoutParams.WRAP_CONTENT;
        lp.height=WindowManager.LayoutParams.WRAP_CONTENT;
       lp.format= PixelFormat.TRANSPARENT;
        manager.addView(imageView, lp);


    }




}

最后需要添加权限

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