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.
*
* <p>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}.</p>
*/
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
* <em>silently fail</em> (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 <em>not</em> 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;
}
测试在魅族华为小米大部分机型上都是可以的，但这个方法也不能保证正确，一些机型上会返回错误即MODE_ERRORED，就是获取不到权限值，这个方法就返回了false，但实际上悬浮窗是可以使用的。
以上这篇Android 获取判断是否有悬浮窗权限的方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持找一找教程网。
