在lagom项目中，我试图使用访问器，但是我得到了一个错误。
java.util.concurrent.completionexception:java.lang.runtimeexception:在java.util.concurrent.completablefuture.encodethrowable（completablefuture）处为访问器testaccessor准备查询时出错。java:273)在java.util.concurrent.completablefuture.unicomposestage（completablefuture。java:991)在java.util.concurrent.completablefuture.thencose（completablefuture。java:2124)在java.util.concurrent.completablefuture.thencose（completablefuture。java:110)在org.test.impl.persist.cassandrarepository.getall（cassandrarepository。java:98)在org.test.impl.workers.worker.lambda$testmessage$2（worker。java:91)在java.util.concurrent.completablefuture.unicompose（completablefuture。java:952)位于java.util.concurrent.completablefuture$unicompose.tryfire（completablefuture。java:926)在java.util.concurrent.completablefuture.postcomplete（completablefuture。java:474)位于java.util.concurrent.completablefuture.complete（completablefuture。java:1962)在com.spotify.futures.listenabletocompletablefuturewrapper.onsuccess（listenabletocompletablefuturewrapper）。java:49)在com.google.common.util.concurrent.futures$callbacklistener.run（futures。java:1237)在com.google.common.util.concurrent.moreexecutors$directexecutor.execute（moreexecutors。java:399)在com.google.common.util.concurrent.abstractfuture.executelistener（抽象未来。java:911)在com.google.common.util.concurrent.abstractfuture.complete（abstractfuture。java:822)在com.google.common.util.concurrent.abstractfuture.set（abstractfuture。java:664)在com.google.common.util.concurrent.abstracttransformfuture$transformfuture.setresult（abstracttransformfuture。java:245)在com.google.common.util.concurrent.abstracttransformfuture.run（abstracttransformfuture。java:177)在com.google.common.util.concurrent.moreexecutors$directexecutor.execute（moreexecutors。java:399)在com.google.common.util.concurrent.abstractfuture.executelistener（抽象未来。java:911)在com.google.common.util.concurrent.abstractfuture.complete（abstractfuture。java:822)在com.google.common.util.concurrent.abstractfuture.set（abstractfuture。java:664)在com.datastax.driver.core.defaultresultsetfuture.inite（defaultresultsetfuture。java:174)在com.datastax.driver.core.requesthandler.setfinalresult（requesthandler。java:198)在com.datastax.driver.core.requesthandler.access$2600（requesthandler。java:50)在com.datastax.driver.core.requesthandler$投机执行.setfinalresult（requesthandler。java:852)在com.datastax.driver.core.requesthandler$投机执行.initiable（requesthandler。java:556)在com.datastax.driver.core.connection$dispatcher.channelread0（连接。java:1087)在com.datastax.driver.core.connection$dispatcher.channelread0（连接。java:1010)在io.netty.channel.simplechannelinboundhandler.channelread（simplechannelinboundhandler。java:105)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:362)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:348)在io.netty.channel.abstractchannelhandlercontext.firechannelread（abstractchannelhandlercontext。java:340)在io.netty.handler.timeout.idlestatehandler.channelread（idlestatehandler。java:286)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:362)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:348)在io.netty.channel.abstractchannelhandlercontext.firechannelread（abstractchannelhandlercontext。java:340)在io.netty.handler.codec.messagetomessagedecoder.channelread（messagetomessagedecoder。java:102)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:362)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:348)在io.netty.channel.abstractchannelhandlercontext.firechannelread（abstractchannelhandlercontext。java:340)在io.netty.handler.codec.bytetomessagedecoder.firechannelread（bytetomessagedecoder。java:310)在io.netty.handler.codec.bytetomessagedecoder.channelread（bytetomessagedecoder。java:284)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:362)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:348)在io.netty.channel.abstractchannelhandlercontext.firechannelread（abstractchannelhandlercontext。java:340)在io.netty.channel.channelinboundhandleradapter.channelread（channelinboundhandleradapter。java:86)在com.datastax.driver.core.inboundtrafficmeter.channelread（inboundtrafficmeter。java:38)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:362)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:348)在io.netty.channel.abstractchannelhandlercontext.firechannelread（abstractchannelhandlercontext。java:340)在io.netty.channel.defaultchannelpipeline$headcontext.channelread（defaultchannelpipeline。java:1434)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:362)在io.netty.channel.abstractchannelhandlercontext.invokechannelread（abstractchannelhandlercontext。java:348)在io.netty.channel.defaultchannelpipeline.firechannelread（defaultchannelpipeline。java:965)在io.netty.channel.nio.abstractniobytechannel$niobytueunsafe.read（abstractniobytechannel。java:163)在io.netty.channel.nio.nioeventloop.processselectedkey（nioeventloop。java:647)在io.netty.channel.nio.nioeventloop.processselectedkeysoptimized（nioeventloop。java:582)在io.netty.channel.nio.nioeventloop.processselectedkeys（nioeventloop。java:499)在io.netty.channel.nio.nioeventloop.run（nioeventloop。java:461)在io.netty.util.concurrent.singlethreadeventexecutor$5.run（singlethreadeventexecutor。java:884)在io.netty.util.concurrent.fastthreadlocalrunnable.run（fastthreadlocalrunnable。java:30)在java.lang.thread.run（线程。java:748)原因：java.lang.runtimeexception:为位于的访问器testaccessor准备查询时出错com.datastax.driver.mapping.accessormapper.prepare（accessormapper。java:61)在com.datastax.driver.mapping.mappingmanager.getaccessor（mappingmanager。java:335)在com.datastax.driver.mapping.mappingmanager.createaccessor（mappingmanager。java:297)在org.test.impl.persist.cassandrarepository.lambda$getall$5（cassandrarepository。java:99)在java.util.concurrent.completablefuture.unicomposestage（completablefuture。java:981) ... 61由于以下原因而忽略的公共帧：java.util.concurrent.executionexception:com.datastax.driver.core.exceptions.operationtimedoutexception:[localhost/127.0.0.1:9042]在com.google.common.util.concurrent.abstractfuture.getdonevalue（abstractfuture）等待服务器响应时超时。java:503)在com.google.common.util.concurrent.abstractfuture.get（抽象未来。java:482)在com.google.common.util.concurrent.abstractfuture$trustedfuture.get（abstractfuture。java:79)在com.datastax.driver.mapping.accessormapper.prepare（accessormapper。java:57) ... 65由于以下原因而忽略的公共帧：com.datastax.driver.core.exceptions.operationtimedoutexception:[localhost/127.0.0.1:9042]在com.datastax.driver.core.requesthandler$投机执行.ontimeout（requesthandler）等待服务器响应时超时。java:825)在com.datastax.driver.core.connection$responsehandler$1.run（连接。java:1392)在io.netty.util.hashedweeltimer$hashedweeltimeout.expire（hashedweeltimer。java:668)在io.netty.util.hashedwheeltimer$hashedwheelbucket.expiretimeouts（hashedwheeltimer。java:743)在io.netty.util.hashedwheeltimer$worker.run（hashedwheeltimer。java:471) ... 省略2个公共框架
存取器

@Accessor
public interface TestAccessor {
    @Query("SELECT * FROM test_table")
    Result<TestTable> getAll();
}

使用

TestAccessor acc = mappingManager.createAccessor(TestAccessor.class);
Result<TestTable> channels = acc.getAll();

提供会话和Map器。

public class Module extends AbstractModule implements ServiceGuiceSupport, AkkaGuiceSupport {
    private static CompletableFuture<Void> codecRegistrationPromise = new CompletableFuture<>();

    @Override
    protected void configure() {
        bindService(TestService.class, TestServiceImpl.class);
    }

    @Provides
    @Singleton
    public CompletionStage<MappingManager> provideMappingManager(CompletionStage<Session> session) {
        return session.thenApply(MappingManager::new));
    }

    @Provides
    public CompletionStage<Cluster> provideCassandraCluster(CompletionStage<Session> session) {
        return session.thenApply(Session::getCluster);
    }

    @Provides
    @Singleton
    public CompletionStage<Session> provideCassandraSession(CassandraSession sessionWrapper) {
        CompletableFuture<Session> future = new CompletableFuture<>();
        completeWithSession(sessionWrapper, future);
        return future;
    }

    private void completeWithSession(CassandraSession sessionWrapper, CompletableFuture<Session> future) {
        sessionWrapper.underlying().whenComplete((session, throwable) -> {
            if (throwable != null) {
                if (throwable instanceof NoServiceLocatorException) {
                    log.error("Failed to obtain Cassandra session, try again", throwable);
                    completeWithSession(sessionWrapper, future);
                } else {
                    log.error("Failed to obtain Cassandra session", throwable);
                    future.completeExceptionally(throwable);
                }
            } else {
                log.info("Cassandra session obtained");
                future.complete(session);
            }
        });
    }
}

在某些类中的用法

@Inject
    public CassandraRepository(CompletionStage<MappingManager> mappingManagerPromise, ActorSystem system) {
        this.mappingManagerPromise = mappingManagerPromise;
        this.system = system;
    }

    mappingManagerPromise.thenApply(mappingManager -> {
                    TestAccessor acc = mappingManager.createAccessor(TestAccessor.class);
Result<TestTable> channels = acc.getAll();
                })

如果我使用mapper.getasync，一切正常。

Mapper<TestTable> mapper = mappingManager.mapper(TestTable.class);
            return toCompletableFuture(mapper.getAsync(id));