Android如何获取判断是否有悬浮窗权限
现在很多应用都会用到悬浮窗，很多国产rom把悬浮窗权限加入控制了，你就需要判断是否有悬浮窗权限，然后做对应操作。
Android 原生有自带权限管理的，只是被隐藏了。看android源码在android.app下就有个AppOpsManager类。
类说明如下：
/** * API for interacting with "application operation" tracking. * * This API is not generally intended for third party application developers; most * features are only available to system applications. Obtain an instance of it through * {@link Context#getSystemService(String) Context.getSystemService} with * {@link Context#APP_OPS_SERVICE Context.APP_OPS_SERVICE}. */上面说明了只对系统应用有用，rom厂商们应该就是利用这个AppOps机制开放一些权限控制。
我们要判断是否有权限该如何做呢？就只能通过反射去判断了。
AppOpsManager的checkOp方法，就是检测是否有某项权限的方法有这些返回值，分别是允许，忽略，错误和默认：
/** * Result from {@link #checkOp}, {@link #noteOp}, {@link #startOp}: the given caller is * allowed to perform the given operation. */ public static final int MODE_ALLOWED = 0; /** * Result from {@link #checkOp}, {@link #noteOp}, {@link #startOp}: the given caller is * not allowed to perform the given operation, and this attempt should * silently fail (it should not cause the app to crash). */ public static final int MODE_IGNORED = 1; /** * Result from {@link #checkOpNoThrow}, {@link #noteOpNoThrow}, {@link #startOpNoThrow}: the * given caller is not allowed to perform the given operation, and this attempt should * cause it to have a fatal error, typically a {@link SecurityException}. */ public static final int MODE_ERRORED = 2; /** * Result from {@link #checkOp}, {@link #noteOp}, {@link #startOp}: the given caller should * use its default security check. This mode is not normally used; it should only be used * with appop permissions, and callers must explicitly check for it and deal with it. */ public static final int MODE_DEFAULT = 3;只有MODE_ALLOWED才是确定有权限的。
类里面checkOp方法如下，三个参数分别是操作id，uid和包名：
/** * Do a quick check for whether an application might be able to perform an operation. * This is not a security check; you must use {@link #noteOp(int, int, String)} * or {@link #startOp(int, int, String)} for your actual security checks, which also * ensure that the given uid and package name are consistent. This function can just be * used for a quick check to see if an operation has been disabled for the application, * as an early reject of some work. This does not modify the time stamp or other data * about the operation. * @param op The operation to check. One of the OP_* constants. * @param uid The user id of the application attempting to perform the operation. * @param packageName The name of the application attempting to perform the operation. * @return Returns {@link #MODE_ALLOWED} if the operation is allowed, or * {@link #MODE_IGNORED} if it is not allowed and should be silently ignored (without * causing the app to crash). * @throws SecurityException If the app has been configured to crash on this op. * @hide */ public int checkOp(int op, int uid, String packageName) { try { int mode = mService.checkOperation(op, uid, packageName); if (mode == MODE_ERRORED) { throw new SecurityException(buildSecurityExceptionMsg(op, uid, packageName)); } return mode; } catch (RemoteException e) { } return MODE_IGNORED; }操作id即op可以在该类中找到静态值定义，android23里面有62种权限，我们需要的是OP_SYSTEM_ALERT_WINDOW=24
知道这些就可以用反射把我们的方法写出了：
/**
* 判断 悬浮窗口权限是否打开
*
* @param context
* @return true 允许 false禁止
*/
public static boolean getAppOps(Context context) {
try {
Object object = context.getSystemService("appops");
if (object == null) {
return false;
}
Class localClass = object.getClass();
Class[] arrayOfClass = new Class[3];
arrayOfClass[0] = Integer.TYPE;
arrayOfClass[1] = Integer.TYPE;
arrayOfClass[2] = String.class;
Method method = localClass.getMethod("checkOp", arrayOfClass);
if (method == null) {
return false;
}
Object[] arrayOfObject1 = new Object[3];
arrayOfObject1[0] = Integer.valueOf(24);
arrayOfObject1[1] = Integer.valueOf(Binder.getCallingUid());
arrayOfObject1[2] = context.getPackageName();
int m = ((Integer) method.invoke(object, arrayOfObject1)).intValue();
return m == AppOpsManager.MODE_ALLOWED;
} catch (Exception ex) {
}
return false;
}