Spring Integration JPA入站通道适配器

问题描述：

我有一个spring-integration message channel，它使用jpa inbound-channel-adapter从数据库中读取.

I have a spring-integration message channel which read from a database using a jpa inbound-channel-adapter.

<int:channel id="logChannel">
    <int:priority-queue capacity="20" />
</int:channel>

<int-jpa:inbound-channel-adapter
    channel="logChannel" entity-class="com.objects.Transactionlog"
    entity-manager-factory="entityManagerFactory" auto-startup="true"
    jpa-query="SELECT x FROM Transactionlog AS x WHERE x.status LIKE '1'" max-results="1">
    <int:poller fixed-rate="5000">
        <int:transactional propagation="REQUIRED"
            transaction-manager="transactionManager" />
    </int:poller>
</int-jpa:inbound-channel-adapter>

这总是只读取表transactionlog的第一行.因此，我想在读取后立即更新每个数据库条目的status.任何人都知道该怎么做吗?

This always reads only the first row of the table transactionlog. So I want to update the status of each database entry just after read. Any body know how to do that?

答

如果max-results="1"对您来说还行，并且每5秒仅收到一个实体适合您的用例，就顺其自然.

If max-results="1" is OK for you and receive only one entity per 5 second is appropiate for your use-case, let it be.

现在如何更新该实体以在下一次民意调查中跳过它.

Now how to update that entity to skip it on the next poll.

<int-jpa:inbound-channel-adapter>具有delete-after-poll="true"选项，该选项允许在检索实体后执行entityManager.remove(entity).

The <int-jpa:inbound-channel-adapter> has delete-after-poll="true" option, which allows to perform entityManager.remove(entity) after an entity retrival.

对，这是从数据库中真正删除的内容.要将其转换为UPDATE，您可以使用以下方式标记您的实体:

Right, it is the real removal from DB. To convert it to the UPDATE, you can mark your entity with:

@SQLDelete(sql = "UPDATE Transactionlog SET status = false WHERE id = ?")

或者类似的东西，适合您.

Or something similar, that is appropiate for you.

另一个功能是交易同步，当您用某些before-commit工厂标记<poller>并在那里进行UPDATE时.像这样:

Another feature is Transaction Synchronization, when you mark your <poller> with some before-commit factory and do UPDATE there. Something like:

<int-jpa:inbound-channel-adapter ...>
    <int:poller fixed-rate="5000">
      <int:transactional propagation="REQUIRED"
           transaction-manager="transactionManager"
           synchronization-factory="txSyncFactory" />
    </int:poller>
<int-jpa:inbound-channel-adapter>

<int:transaction-synchronization-factory id="txSyncFactory">
    <int:before-commit channel="updateEntityChannel" />
</int:transaction-synchronization-factory>

<int:chain input-channel="updateEntityChannel">
   <int:enricher>
       <int:property name="status" value="true"/>
   </int:enricher>
   <int-jpa:outbound-channel-adapter entity-manager="entityManager"/>
</int:chain/>

类似的东西.

Spring Integration JPA入站通道适配器

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