安卓，懸浮窗權限動態請求（SYSTEM_ALERT_WINDOW）

---

懸浮窗權限請求，示例：

package com.sc.demo;

import android.content.Intent;
import android.os.Bundle;

import com.sc.permission.FloatTool;
import android.app.Activity;
import com.sci.androidpermission.R;

/**  
 * 權限請求示例
 */
public class MainActivity extends Activity
{	
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		// this.setContentView(R.layout.activity_main);
		
		FloatTool.RequestOverlayPermission(this);
	}
	
	/** Activity執行結果 */
	protected void onActivityResult(int requestCode, int resultCode, Intent data)
	{
		super.onActivityResult(requestCode, resultCode, data);
		FloatTool.onActivityResult(requestCode, resultCode, data, this);
	}
}

package com.sc.permission;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.provider.Settings;


/**  
 * FloatTool.java:應用懸浮窗權限請求
 * 
 * AndroidMainifest.xml中添加： <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
 * 
 * 用法：
 * 1、請求懸浮窗權限：FloatTool.RequestOverlayPermission(this);
 * 2、處理懸浮窗權限請求結果：FloatTool.onActivityResult(requestCode, resultCode, data, this);
 * -----
 * 2019-9-19 下午3:10:34
 * scimence 
 */
public class FloatTool
{
	public static boolean CanShowFloat = false;
	
	private static final int REQUEST_OVERLAY = 5004;
	
	/** 動態請求懸浮窗權限 */
	public static void RequestOverlayPermission(Activity Instatnce)
	{
		if (Build.VERSION.SDK_INT >= 23)
		{
			if (!Settings.canDrawOverlays(Instatnce))
			{
				String ACTION_MANAGE_OVERLAY_PERMISSION = "android.settings.action.MANAGE_OVERLAY_PERMISSION";
				Intent intent = new Intent(ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + Instatnce.getPackageName()));
				
				Instatnce.startActivityForResult(intent, REQUEST_OVERLAY);
			}
			else
			{	
				CanShowFloat = true;
			}
		}
	}
	
	/** 浮窗權限請求，Activity執行結果，回調函數 */
	public static void onActivityResult(int requestCode, int resultCode, Intent data, final Activity Instatnce)
	{
		// Toast.makeText(activity, "onActivityResult設置權限！", Toast.LENGTH_SHORT).show();
		if (requestCode == REQUEST_OVERLAY)		// 從應用權限設置界面返回
		{
			if(resultCode == Activity.RESULT_OK)
			{
				CanShowFloat = true;		// 設置標識爲可顯示懸浮窗
			}
			else
			{
				CanShowFloat = false;
				
				if (!Settings.canDrawOverlays(Instatnce))	// 若當前未允許顯示懸浮窗，則提示授權
				{
					AlertDialog.Builder builder = new AlertDialog.Builder(Instatnce);
					builder.setCancelable(false);
					builder.setTitle("懸浮窗權限未授權");
					builder.setMessage("應用需要懸浮窗權限，以展示浮標");
					builder.setPositiveButton("去添加 權限", new DialogInterface.OnClickListener()
					{
						@Override
						public void onClick(DialogInterface dialog, int which)
						{
							dialog.dismiss();
							
							RequestOverlayPermission(Instatnce);
						}
					});
					
					builder.setNegativeButton("拒絕則 退出", new DialogInterface.OnClickListener()
					{
						@Override
						public void onClick(DialogInterface dialog, int which)
						{
							dialog.dismiss();
							
							// 若拒絕了所需的權限請求，則退出應用
							Instatnce.finish();
							System.exit(0);
						}
					});
					builder.show();
				}
			}
		}
	}
}