現在很多應用都有這樣的功能，比如360等安全衛士，手機管家之內的應用。

效果圖：

一、實現原理及移動思路

呼叫WindowManager，並設定WindowManager.LayoutParams的相關屬性，通過WindowManager的addView方法建立View，這樣產生出來的View根據WindowManager.LayoutParams屬性不同，效果也就不同了。比如建立系統頂級視窗，實現懸浮視窗效果！然後通過覆寫懸浮View中onTouchEvent方法來改變windowMananager.LayoutParams中x和y的值來實現自由移動懸浮視窗。

二、示例程式碼

先看看懸浮View的程式碼把

package com.example.suspend;

import android.content.Context;
import android.util.Log;
import android.view.MotionEvent;
import android.view.WindowManager;
import android.widget.ImageView;

public class MyFloatView extends ImageView {
	private float mTouchStartX;
	private float mTouchStartY;
	private float x;
	private float y;

	private WindowManager wm = (WindowManager) getContext()
			.getApplicationContext().getSystemService("window");
	// 此wmParams變數為獲取的全域性變數，用以儲存懸浮視窗的屬性
	private WindowManager.LayoutParams wmParams = ((MyApplication) getContext()
			.getApplicationContext()).getMywmParams();

	public MyFloatView(Context context) {
		super(context);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		// 獲取相對螢幕的座標，即以螢幕左上角為原點
		x = event.getRawX();
		y = event.getRawY() - 25; // 25是系統狀態列的高度
		Log.i("currP", "currX" + x + "====currY" + y);

		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN: // 捕獲手指觸控按下動作
			// 獲取相對View的座標，即以此View左上角為原點
			mTouchStartX = event.getX();
			mTouchStartY = event.getY();
			Log.i("startP", "startX" + mTouchStartX + "====startY"
					+ mTouchStartY);
			break;
		case MotionEvent.ACTION_MOVE://捕獲手指觸控移動動作            
			updateViewPosition();  
			break;
		case MotionEvent.ACTION_UP://捕獲手指觸控離開動作  
			updateViewPosition();  
			mTouchStartX=mTouchStartY=0;  
			break;
		default:
			break;
		}
		return true;
	}

	private void updateViewPosition() {
		//更新浮動視窗位置引數  
		wmParams.x = (int)(x - mTouchStartX);
		wmParams.y = (int)(y - mTouchStartY);
		wm.updateViewLayout(this, wmParams);//重新整理顯示   
	}
}
 

示例程式碼如下：

package com.example.suspend;

import android.app.Application;
import android.view.WindowManager;

public class MyApplication extends Application {
	private WindowManager.LayoutParams wmParams = new WindowManager.LayoutParams();

	@Override
	public void onCreate() {
		// TODO Auto-generated method stub
		super.onCreate();
	}

	public WindowManager.LayoutParams getMywmParams() {
		return wmParams;

	}

}
 

package com.example.suspend;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.view.Gravity;
import android.view.WindowManager;
import android.view.WindowManager.LayoutParams;

public class MainActivity extends Activity {
	private WindowManager wm;
	private WindowManager.LayoutParams wmParams;
	private MyFloatView myFV;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		// 建立懸浮視窗
		createFloatView();
	}

	private void createFloatView() {
		myFV = new MyFloatView(getApplicationContext());
		myFV.setImageResource(R.drawable.ic_launcher);
		// 獲取WindowManager
		wm = (WindowManager) getApplicationContext().getSystemService("window");
		// 設定LayoutParams(全域性變數）相關引數
		wmParams = ((MyApplication) getApplication()).getMywmParams();

		wmParams.type = LayoutParams.TYPE_PHONE;// 設定window type
		wmParams.format = PixelFormat.RGBA_8888;// 設定圖片格式，效果為背景透明
		// 設定Window flag
		wmParams.flags = LayoutParams.FLAG_NOT_TOUCH_MODAL
				| LayoutParams.FLAG_NOT_FOCUSABLE;
		/*
		 * 
		 * 下面的flags屬性的效果形同“鎖定”。
		 * 
		 * 懸浮窗不可觸控，不接受任何事件,同時不影響後面的事件響應。
		 * 
		 * wmParams.flags=LayoutParams.FLAG_NOT_TOUCH_MODAL
		 * 
		 * | LayoutParams.FLAG_NOT_FOCUSABLE
		 * 
		 * | LayoutParams.FLAG_NOT_TOUCHABLE;
		 */
		wmParams.gravity = Gravity.LEFT | Gravity.TOP;// 調整懸浮視窗至左上角，便於調整座標
		// 以螢幕左上角為原點，設定x、y初始值
		wmParams.x = 0;
		wmParams.y = 0;
		// 設定懸浮視窗長寬資料
		wmParams.width = 40;
		wmParams.height = 40;
		// 顯示myFloatView影象
		wm.addView(myFV, wmParams);
	}

	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		// 在程式退出(Activity銷燬）時銷燬懸浮視窗
		wm.removeView(myFV);
	}
}

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