面试题：Kotlin实现Android通知的点击交互与权限关联

Question

在Kotlin的Android开发中，当用户点击通知后，要启动一个特定的Activity，并且这个功能依赖于某个特定权限（如存储权限），请描述实现此功能的完整流程，并写出核心代码，包括权限请求和处理逻辑。

Answer 1

1. 权限声明

在 AndroidManifest.xml 文件中声明所需权限，例如存储权限：

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2. 权限请求逻辑

在 Activity 中请求权限：

import android.content.pm.PackageManager
import android.os.Bundle
import android.widget.Toast
import androidx.activity.result.contract.ActivityResultContracts
import androidx.appcompat.app.AppCompatActivity
import androidx.core.content.ContextCompat

class MainActivity : AppCompatActivity() {

    private val storagePermissionLauncher = registerForActivityResult(
        ActivityResultContracts.RequestPermission()
    ) { isGranted: Boolean ->
        if (isGranted) {
            Toast.makeText(this, "权限已授予", Toast.LENGTH_SHORT).show()
        } else {
            Toast.makeText(this, "权限被拒绝", Toast.LENGTH_SHORT).show()
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        if (ContextCompat.checkSelfPermission(
                this,
                android.Manifest.permission.WRITE_EXTERNAL_STORAGE
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            storagePermissionLauncher.launch(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
        }
    }
}

3. 创建通知并设置点击启动特定Activity

在发送通知的地方，创建 PendingIntent 用于启动特定 Activity：

import android.app.Notification
import android.app.NotificationChannel
import android.app.NotificationManager
import android.content.Context
import android.content.Intent
import android.os.Build
import android.widget.RemoteViews
import androidx.core.app.NotificationCompat
import androidx.core.app.NotificationManagerCompat

class NotificationUtil {

    companion object {
        private const val CHANNEL_ID = "my_channel_id"
        private const val NOTIFICATION_ID = 1

        fun sendNotification(context: Context) {
            createNotificationChannel(context)

            val intent = Intent(context, SpecificActivity::class.java)
            intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
            val pendingIntent: PendingIntent = PendingIntent.getActivity(
                context,
                0,
                intent,
                PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
            )

            val notification: Notification = NotificationCompat.Builder(context, CHANNEL_ID)
               .setSmallIcon(R.drawable.ic_notification)
               .setContentTitle("通知标题")
               .setContentText("通知内容")
               .setContentIntent(pendingIntent)
               .setAutoCancel(true)
               .build()

            with(NotificationManagerCompat.from(context)) {
                notify(NOTIFICATION_ID, notification)
            }
        }

        private fun createNotificationChannel(context: Context) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                val name = "Channel Name"
                val descriptionText = "Channel Description"
                val importance = NotificationManager.IMPORTANCE_DEFAULT
                val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
                    description = descriptionText
                }
                val notificationManager: NotificationManager =
                    context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
                notificationManager.createNotificationChannel(channel)
            }
        }
    }
}

4. 特定Activity（SpecificActivity）

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity

class SpecificActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_specific)
    }
}

在上述代码中，首先声明了存储权限，然后在 MainActivity 中请求权限。NotificationUtil 类用于发送通知，并设置点击通知后启动 SpecificActivity。SpecificActivity 是点击通知后启动的特定页面。