Akka持久化快照存储配置错误：求插件类配置值及补充配置

Hey there! Let's walk through fixing your Akka Persistence setup step by step—you're close, just a couple of small tweaks needed.

1. Fix the Snapshot Store Class & Config Typo #

First, let's tackle the error you're seeing: the snapshot store class is missing, and there's a sneaky typo in your config that's making things worse.

The Issues #

• You have a typo: snaphot-store should be snapshot-store (you missed an 's' in two places)
• The required akka.persistence.snapshot-store.local.class property needs the fully qualified class name of Akka's built-in local snapshot store implementation.

Corrected reference.conf #

akka.persistence.journal.plugin="akka.persistence.journal.leveldb"
akka.persistence.snapshot-store.plugin="akka.persistence.snapshot-store.local"  # Fixed typo here
akka.persistence.journal.leveldb.dir="target/sample/leveldb"
akka.persistence.snapshot-store.local.dir="target/sample/snapshots"  # Fixed typo here
akka.persistence.journal.leveldb.native=off
akka.persistence.snapshot-store.local.class="akka.persistence.snapshot.local.LocalSnapshotStore"  # Added correct class

What Each Config Does #

• akka.persistence.journal.leveldb.dir: Defines where LevelDB saves its journal files
• akka.persistence.snapshot-store.local.dir: Sets the disk location for snapshot files
• akka.persistence.journal.leveldb.native=off: Uses the Java-based LevelDB implementation (avoids platform-specific native dependencies)
• akka.persistence.snapshot-store.local.class: Points to Akka's official local snapshot store implementation

2. Fix Message Sending in Your Main Class #

Looking at your main class code, you're sending Increment(3) directly to the actor—but your Counter's receiveCommand only handles Cmd(op) messages. Those raw Increment/Decrement messages are being ignored right now!

Corrected Main Class Code #

import akka.actor._
import Counter._

object Main extends App {
  val system = ActorSystem("persistent")
  val persistentActor = system.actorOf(Props[Counter], "counter")
  
  // Wrap operations in Cmd as defined in your Counter companion object
  persistentActor ! Cmd(Increment(3))
  persistentActor ! Cmd(Increment(5))
  persistentActor ! Cmd(Decrement(2))
  persistentActor ! "print"
  
  Thread.sleep(5000L)
  system.terminate()
}

3. Expected Output After Fixes #

Once you apply these changes, running your main class should produce output like this:

Starting...
counter received command Increment(3)
counter received command Increment(5)
counter received command Decrement(2)
current state of the counter is State(6)

Key Takeaways #

• Always double-check config spelling (typos like snaphot-store are easy to miss!)
• Make sure your messages match what your actor's receive handlers expect
• For Akka Persistence default plugins, use the official implementation classes provided by the framework

内容的提问来源于stack exchange，提问作者user51