如何将PendingIntent存入SharedPreferences并在其存在时执行操作？

Hey there! Storing a PendingIntent directly in SharedPreferences isn't straightforward because it's a complex object that can't be serialized like primitive types (strings, integers, etc.). But since PendingIntent implements the Parcelable interface, we can use that to convert it to a byte array—this lets us save it to SharedPreferences and reconstruct it later. Here's a step-by-step solution:

Step 1: Create Utility Functions for Conversion #

First, make helper functions to convert between PendingIntent and ByteArray:

import android.os.Parcel
import android.app.PendingIntent

fun pendingIntentToBytes(pendingIntent: PendingIntent): ByteArray {
    val parcel = Parcel.obtain()
    pendingIntent.writeToParcel(parcel, 0)
    val bytes = parcel.marshall()
    parcel.recycle() // Always recycle parcels to avoid memory leaks
    return bytes
}

fun bytesToPendingIntent(bytes: ByteArray): PendingIntent? {
    val parcel = Parcel.obtain()
    parcel.unmarshall(bytes, 0, bytes.size)
    parcel.setDataPosition(0) // Reset parcel position to start reading
    val pendingIntent = PendingIntent.CREATOR.createFromParcel(parcel)
    parcel.recycle()
    return pendingIntent
}

Step 2: Save PendingIntent to SharedPreferences #

Once you have your PendingIntent instance, convert it to a byte array and store it:

import android.content.Context
import android.content.Intent

// Example: Create a PendingIntent for an Activity
val intent = Intent(context, YourTargetActivity::class.java)
val myPendingIntent = PendingIntent.getActivity(
    context,
    0, // Request code (use a unique value if you have multiple PendingIntents)
    intent,
    PendingIntent.FLAG_IMMUTABLE // Use FLAG_MUTABLE if you need to modify the intent later
)

// Save to SharedPreferences
val sharedPrefs = context.getSharedPreferences("AppPreferences", Context.MODE_PRIVATE)
sharedPrefs.edit()
    .putByteArray("stored_pending_intent", pendingIntentToBytes(myPendingIntent))
    .apply()

Step 3: Retrieve and Use the Stored PendingIntent #

Later, check if the PendingIntent exists in SharedPreferences, reconstruct it, and perform your specific action:

val sharedPrefs = context.getSharedPreferences("AppPreferences", Context.MODE_PRIVATE)
val storedPiBytes = sharedPrefs.getByteArray("stored_pending_intent", null)

storedPiBytes?.let { bytes ->
    val retrievedPendingIntent = bytesToPendingIntent(bytes)
    retrievedPendingIntent?.let { pi ->
        // Execute your specific operation here
        try {
            pi.send() // Example: Trigger the PendingIntent
        } catch (e: PendingIntent.CanceledException) {
            // Handle case where the PendingIntent is no longer valid
            e.printStackTrace()
        }
    }
}

Important Notes #

• PendingIntent Validity: A stored PendingIntent might become invalid if the target component (Activity/Service/BroadcastReceiver) is updated, uninstalled, or if the app's package name changes. Always handle exceptions like CanceledException and consider clearing stored PendingIntents when your app is updated.
• Flags: Use FLAG_IMMUTABLE (default for API 31+) unless you need to modify the intent later (use FLAG_MUTABLE in that case). Using the wrong flag can cause runtime errors on newer Android versions.
• Multiple PendingIntents: If you need to store an ArrayList<PendingIntent>, convert each to a byte array, then use a library like Gson to convert the list of byte arrays to a JSON string for storage, or use a Parcelable array.

内容的提问来源于stack exchange，提问作者Fahad Shahid