当项目中compileSdkVersion以及targetSdkVersion从22升级到23以及更高之后，就需要注意到6.0权限的动态申请问题，以及7.0系统访问存储空间的时候，FileProvider的使用，如果没有注意到或者使用不好，则会引起app的Crash问题
6.0动态权限适配
6.0系统以后，Android对于敏感和危险权限，为了用户信息的安全，禁止随意申请，必须动态申请，经过用户同意之后，才可以获得和使用此权限
检查权限 checkSelfPermission
主要通过ActivityCompat或者ContextCompat中的checkSelfPermission方法检查，返回值为int
- PackageManager.PERMISSION_GRANTED 授权同意
- PackageManager.PERMISSION_DENIED 授权失败，权限请求被拒绝
int result = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_SETTINGS);
/**
* Determine whether you have been granted a particular permission.
*
* @param permission The name of the permission being checked.
*
* @return {@link android.content.pm.PackageManager#PERMISSION_GRANTED} if you have the
* permission, or {@link android.content.pm.PackageManager#PERMISSION_DENIED} if not.
*
* @see android.content.pm.PackageManager#checkPermission(String, String)
*/
public static int checkSelfPermission(@NonNull Context context, @NonNull String permission) {
if (permission == null) {
throw new IllegalArgumentException("permission is null");
}
return context.checkPermission(permission, android.os.Process.myPid(), Process.myUid());
}
再次请求确认 shouldShowRequestPermissionRationale
ActivityCompat.shouldShowRequestPermissionRationale(Activity activity, String permission)
方法源码解释
/**
* Gets whether you should show UI with rationale for requesting a permission.
* You should do this only if you do not have the permission and the context in
* which the permission is requested does not clearly communicate to the user
* what would be the benefit from granting this permission.
*
* For example, if you write a camera app, requesting the camera permission
* would be expected by the user and no rationale for why it is requested is
* needed. If however, the app needs location for tagging photos then a non-tech
* savvy user may wonder how location is related to taking photos. In this case
* you may choose to show UI with rationale of requesting this permission.
*
*
* @param activity The target activity.
* @param permission A permission your app wants to request.
* @return Whether you can show permission rationale UI.
*
* @see #checkSelfPermission(android.content.Context, String)
* @see #requestPermissions(android.app.Activity, String[], int)
*/
public static boolean shouldShowRequestPermissionRationale(@NonNull Activity activity,
@NonNull String permission) {
if (Build.VERSION.SDK_INT >= 23) {
return ActivityCompatApi23.shouldShowRequestPermissionRationale(activity, permission);
}
return false;
}
判断是否有必要向用户解释为什么要这项权限。如果应用第一次请求过此权限，但是被用户拒绝了，则之后调用该方法将返回 true，此时就有必要向用户详细说明需要此权限的原因，返回true的时候，基本上就是申请权限操作最后一次挣扎的机会了
如果第二次再请求此权限时，用户勾选了权限请求对话框的“不再询问”，则此方法返回 false。如果设备规范禁止应用拥有该权限，此方法也返回 false。
请求权限 requestPermissions
ActivityCompat.requestPermissions(this, permission, 123)
权限申请结果处理
重写Activity中的onRequestPermissionsResult方法
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array, grantResults: IntArray) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults)
var isGranted = false
when (requestCode) {
PERMISSION_REQUEST_SINGLE -> {
isGranted = if (grantResults.size == 1) grantResults[0] == PackageManager.PERMISSION_GRANTED else false
}
PERMISSION_REQUEST_MULTI -> {
isGranted = true
for (it in grantResults) {
if (it == PackageManager.PERMISSION_DENIED) {
isGranted = false
break
}
}
}
}
if (isGranted) {
onPermissonGranted()
} else {
onPermissonGrantFailed()
}
}
对于shouldShowRequestPermissionRationale方法的常规使用如下代码：
override fun onPermissionGrantFailed() {
super.onPermissionGrantFailed()
var isSend = ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
var dialog = AlertDialog.Builder(this).apply {
setMessage("该功能需要拍照权限，否则功能将不能使用")
setPositiveButton(if (isSend) "重新申请" else "手动开启")
{ dialog, which ->
if (isSend) {
requestPermission(PERMISSION_REQUEST_MULTI, Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE)
} else {
startActivity(Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS).apply {
data = Uri.fromParts("package", packageName, null)
})
}
}
setNegativeButton("取消") { dialog, which ->
dialog.dismiss()
}
}
dialog.show()
}
7.0 FileProvider的使用
FileProvider是7.0系统新增的功能类，主要是为了访问SD卡文件或者系统应用之间共享文件的时候，采用content://author的方法来兼容处理，官方解释如下：
要在应用间共享文件，您应发送一项 content:// URI，并授予 URI 临时访问权限。进行此授权的最简单方式是使用 FileProvider 类。如需了解有关权限和共享文件的详细信息，请参阅共享文件。
https://developer.android.com/about/versions/nougat/android-7.0-changes.html#accessibility
AndroidManifest中声明FileProvider
kt_file_paths
代表设备的根目录new File("/"); 代表context.getFilesDir() 代表context.getCacheDir() 代表Environment.getExternalStorageDirectory() 代表context.getExternalFilesDirs() -
代表getExternalCacheDirs()
FileProvider的源码如下图:
FileProvider.jpg
每个节点都包含name和path两个属性
path表示根目录中的子目录,比如：
上述例子中的external代替了/storage/emulated/0/pics/这个绝对路径的映射 content://com.kt.video.fileProvider/external/1528710742956.jpg
常用的打开相机代码修改:
private fun openCamera() {
var pic = Environment.getExternalStorageDirectory().absolutePath + "/pics/" + System.currentTimeMillis() + ".jpg"
var file = File(pic)
var uri: Uri? = null
try {
uri = if (Build.VERSION.SDK_INT > Build.VERSION_CODES.N) {
FileProvider.getUriForFile(this@KtFileProviderActivity, "$packageName.fileProvider", file)
} else {
Uri.fromFile(file)
}
startActivity(Intent(MediaStore.ACTION_IMAGE_CAPTURE).apply {
putExtra(MediaStore.EXTRA_OUTPUT, uri)
})
} catch (e: Exception) {
e.printStackTrace()
}
}
安装apk的代码修改：
fun installApk(context: Context, fileName: String) {
val apkFile = File(fileName)
if (apkFile.exists()) {
context.startActivity(Intent(Intent.ACTION_VIEW).apply {
val data: Uri
// 判断系统版本是否大于等于7.0
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
data = FileProvider.getUriForFile(context, "$packageName.fileProvider", apkFile)
// 给目标应用一个临时授权
addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
} else {
data = Uri.fromFile(apkFile)
}
setDataAndType(data, "application/vnd.android.package-archive")
addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
})
} else {
Toast.makeText(context, context.getString(R.string.apk_not_exit), Toast.LENGTH_SHORT).show()
}
}