以请求一个保存图片的权限为例。
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
1.在AndroidMainfest文件中添加上面代码块内的权限
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.gallery">
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.AppCompat.Light.DarkActionBar">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
2.事件监听,弹出申请权限对话框
//保存图片事件, 动态申请权限
saveButton.setOnClickListener{
if (Build.VERSION.SDK_INT < 29 && ContextCompat.checkSelfPermission(
requireContext(),
Manifest.permission.WRITE_EXTERNAL_STORAGE
) != PackageManager.PERMISSION_GRANTED
) {
//没有权限,弹出一个请求权限对话框
requestPermissions(arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE), 1)
} else {
//已有权限,处理事件
viewLifecycleOwner.lifecycleScope.launch {
//lifecycleScope使协程的生命周期随着activity的生命周期变化
savePhoto()
}
}
}
3.回调结果,用户是否允许使用权限
在类中,重载onRequestPermissionsResult函数
//请求权限对话框处理
override fun onRequestPermissionsResult(
requestCode: Int,
permissions: Array<out String>,
grantResults: IntArray
) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults)
//处理返回结果
when (requestCode) {
1 -> {
if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//权限通过,执行事件
viewLifecycleOwner.lifecycleScope.launch {
//lifecycleScope使协程的生命周期随着activity的生命周期变化
savePhoto()
}
} else {
//用户不允许使用该权限,失败提示
Toast.makeText(requireContext(), "存储失败", Toast.LENGTH_SHORT).show()
}
}
}
}