mysql - Lagom 与 MySQL Db 连接

Question

我想将 lagom 连接到 MySQL 数据库，我下载了一个在 Lagom 站点创建的项目。我在 hello-impl pom 中添加了以下依赖项，并在 applicaiont.conf 中配置了数据库详细信息。

<dependency>
        <groupId>com.lightbend.lagom</groupId>
        <artifactId>lagom-javadsl-persistence-jdbc_${scala.binary.version}</artifactId>
        <version>${lagom.version}</version>
</dependency>

应用程序配置文件

db.default {
  driver = "com.mysql.jdbc.Driver"
  url = "jdbc:mysql://localhost:3306/test"
  user = "root"
  password = ""
}
jdbc-defaults.slick.profile = "slick.jdbc.MySQLProfile$"
lagom.persistence.jdbc.create-tables.auto = true

之后我运行该应用程序，出现以下错误。什么错误。我是 lagom 的新手，所以请详细解释一下。

{"name":"akka.pattern.AskTimeoutException: Ask timed out on [Actor[akka://hello-impl-application/system/sharding/HelloEntity#976224651]] after [10000 ms]. Message of type [com.lightbend.lagom.javadsl.persistence.CommandEnvelope]. A typical reason for `AskTimeoutException` is that the recipient actor didn't send a reply.","detail":"akka.pattern.AskTimeoutException: Ask timed out on [Actor[akka://hello-impl-application/system/sharding/HelloEntity#976224651]] after [10000 ms]. Message of type [com.lightbend.lagom.javadsl.persistence.CommandEnvelope]. A typical reason for `AskTimeoutException` is that the recipient actor didn't send a reply.\r\n\tat akka.pattern.PromiseActorRef$.$anonfun$defaultOnTimeout$1(AskSupport.scala:635)\r\n\tat akka.pattern.PromiseActorRef$.$anonfun$apply$1(AskSupport.scala:650)\r\n\tat akka.actor.Scheduler$$anon$4.run(Scheduler.scala:205)\r\n\tat scala.concurrent.Future$InternalCallbackExecutor$.unbatchedExecute(Future.scala:870)\r\n\tat scala.concurrent.BatchingExecutor.execute(BatchingExecutor.scala:109)\r\n\tat scala.concurrent.BatchingExecutor.execute$(BatchingExecutor.scala:103)\r\n\tat scala.concurrent.Future$InternalCallbackExecutor$.execute(Future.scala:868)\r\n\tat akka.actor.LightArrayRevolverScheduler$TaskHolder.executeTask(LightArrayRevolverScheduler.scala:328)\r\n\tat akka.actor.LightArrayRevolverScheduler$$anon$4.executeBucket$1(LightArrayRevolverScheduler.scala:279)\r\n\tat akka.actor.LightArrayRevolverScheduler$$anon$4.nextTick(LightArrayRevolverScheduler.scala:283)\r\n\tat akka.actor.LightArrayRevolverScheduler$$anon$4.run(LightArrayRevolverScheduler.scala:235)\r\n\tat java.lang.Thread.run(Thread.java:748)\r\n"}

Answer 1

在使用 MySQL 时，我们需要自己创建数据库。在 Cassandra 中，它会在 conf 文件中定义名称后创建 key 空间，但在 MySQL 中，我们必须手动创建一个数据库，例如 test 在您的情况下 ->

create database test;

那么你就不会遇到 Ask timed out 异常了。