对Gemfire 6.5区域的OQL查询中的对象调用方法

Question

我正在使用下面的Java 6代码来查询Gemfire 6.5缓存。

我的问题是，我试图使用WHERE从区域中的对象中使用一个方法调用来过滤我的结果，但出于某种原因，它抱怨java.lang.String没有包含我在讨论MyEntity时试图使用的方法，因为缓存中的对象就是这个类。

我最好的猜测是，去西化有一些有趣的地方，类作为字符串类出现，在这个类中，它不包含方法，然后用方法将其转换为MyEntity类，并且代码试图在类转换之前从MyEntity调用方法。

package gemfire.run;

import com.gemstone.gemfire.DataSerializable;
import com.gemstone.gemfire.Instantiator;
import com.gemstone.gemfire.cache.client.ClientCache;
import com.gemstone.gemfire.cache.client.ClientCacheFactory;
import com.gemstone.gemfire.cache.query.Query;
import com.gemstone.gemfire.cache.query.QueryService;
import com.gemstone.gemfire.cache.query.SelectResults;

import entity.MyEntity;

public class QueryServerCache {
@SuppressWarnings({ "unchecked", "unused" })
public static void main(String[] args) {

    System.out.println("Start Program");

    Instantiator.register(new Instantiator(MyEntity.class, 60151) {
        @Override
        public DataSerializable newInstance() {
            return new MyEntity();
        }
    });

    ClientCache clientCache = new ClientCacheFactory().addPoolServer("myServer.net", 12345).set("log-level", "error").create();

    QueryService queryService = clientCache.getQueryService();

    Query q1 = queryService.newQuery("SELECT DISTINCT * FROM /rootregion/traderegion o WHERE o.getEventId = 'X123'");
    Query q = queryService.newQuery("SELECT * FROM /rootregion/traderegion LIMIT 10");
    try {
        SelectResults<MyEntity> results = (SelectResults<MyEntity>) q1.execute();
        System.out.println("\n" + results.size() + "\n");
        for (MyEntity o : results) {
            System.out.println(o.getEventId());
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

    System.out.println("\nExit Program");

}
}

代码的堆栈跟踪是：

Start Program
com.gemstone.gemfire.cache.client.ServerOperationException: While performing a remote query
at com.gemstone.gemfire.cache.client.internal.AbstractOp.processChunkedResponse(AbstractOp.java:323)
at com.gemstone.gemfire.cache.client.internal.QueryOp$QueryOpImpl.processResponse(QueryOp.java:145)
at com.gemstone.gemfire.cache.client.internal.AbstractOp.attemptReadResponse(AbstractOp.java:150)
at com.gemstone.gemfire.cache.client.internal.AbstractOp.attempt(AbstractOp.java:363)
at com.gemstone.gemfire.cache.client.internal.ConnectionImpl.execute(ConnectionImpl.java:245)
at com.gemstone.gemfire.cache.client.internal.pooling.PooledConnection.execute(PooledConnection.java:321)
at com.gemstone.gemfire.cache.client.internal.OpExecutorImpl.executeWithPossibleReAuthentication(OpExecutorImpl.java:646)
at com.gemstone.gemfire.cache.client.internal.OpExecutorImpl.execute(OpExecutorImpl.java:108)
at com.gemstone.gemfire.cache.client.internal.OpExecutorImpl.execute(OpExecutorImpl.java:84)
at com.gemstone.gemfire.cache.client.internal.PoolImpl.execute(PoolImpl.java:610)
at com.gemstone.gemfire.cache.client.internal.QueryOp.execute(QueryOp.java:47)
at com.gemstone.gemfire.cache.client.internal.ServerProxy.query(ServerProxy.java:80)
at com.gemstone.gemfire.cache.query.internal.DefaultQuery.executeOnServer(DefaultQuery.java:248)
at com.gemstone.gemfire.cache.query.internal.DefaultQuery.execute(DefaultQuery.java:135)
at com.gemstone.gemfire.cache.query.internal.DefaultQuery.execute(DefaultQuery.java:117)
at gemfire.run.QueryServerCache.main(QueryServerCache.java:33)
Caused by: com.gemstone.gemfire.cache.query.NameNotFoundException: No public attribute named ' getEventId ' was found in class  java.lang.String
at com.gemstone.gemfire.cache.query.internal.AttributeDescriptor.getReadMember(AttributeDescriptor.java:184)
at com.gemstone.gemfire.cache.query.internal.AttributeDescriptor.read(AttributeDescriptor.java:70)
at com.gemstone.gemfire.cache.query.internal.AttributeDescriptor.read(AttributeDescriptor.java:56)
at com.gemstone.gemfire.cache.query.internal.PathUtils.evaluateAttribute(PathUtils.java:63)
at com.gemstone.gemfire.cache.query.internal.CompiledPath.evaluate(CompiledPath.java:127)
at com.gemstone.gemfire.cache.query.internal.CompiledComparison.evaluate(CompiledComparison.java:72)
at com.gemstone.gemfire.cache.query.internal.CompiledSelect.doNestedIterations(CompiledSelect.java:449)
at com.gemstone.gemfire.cache.query.internal.CompiledSelect.doNestedIterations(CompiledSelect.java:490)
at com.gemstone.gemfire.cache.query.internal.CompiledSelect.doIterationEvaluate(CompiledSelect.java:376)
at com.gemstone.gemfire.cache.query.internal.CompiledSelect.evaluate(CompiledSelect.java:304)
at com.gemstone.gemfire.cache.query.internal.DefaultQuery.executeUsingContext(DefaultQuery.java:382)
at com.gemstone.gemfire.cache.query.internal.DefaultQuery.execute(DefaultQuery.java:181)
at com.gemstone.gemfire.cache.query.internal.DefaultQuery.execute(DefaultQuery.java:117)
at com.gemstone.gemfire.internal.cache.tier.sockets.BaseCommand.processQueryUsingParams(BaseCommand.java:1216)
at com.gemstone.gemfire.internal.cache.tier.sockets.BaseCommand.processQuery(BaseCommand.java:1167)
at com.gemstone.gemfire.internal.cache.tier.sockets.command.Query.cmdExecute(Query.java:76)
at com.gemstone.gemfire.internal.cache.tier.sockets.BaseCommand.execute(BaseCommand.java:133)
at com.gemstone.gemfire.internal.cache.tier.sockets.ServerConnection.doNormalMsg(ServerConnection.java:758)
at com.gemstone.gemfire.internal.cache.tier.sockets.ServerConnection.doOneMessage(ServerConnection.java:879)
at com.gemstone.gemfire.internal.cache.tier.sockets.ServerConnection.run(ServerConnection.java:1067)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at com.gemstone.gemfire.internal.cache.tier.sockets.AcceptorImpl$1$1.run(AcceptorImpl.java:504)
at java.lang.Thread.run(Thread.java:662)

Exit Program

使用查询Q(而不是q1 )运行它很好，因此它似乎确实能够访问MyEntity进行反序列化，但是，如果我尝试如下所示：

Query q1 = queryService.newQuery("SELECT DISTINCT * FROM /rootregion/traderegion o WHERE (MyEntity)o.getEventId = 'X123'");

我不知道MyEntity是什么，这是个错误。

Answer 1

结果发现，在这个区域中使用的是一个心跳空字符串对象，我只需过滤结果就可以删除它，然后再用我的MyEntity特定的方法和变量进行进一步过滤。

Query q = queryService.newQuery("SELECT * FROM (SELECT * FROM /rootregion/traderegion WHERE toString()!='') WHERE eventId='X123'");

这过滤掉了空对象，只留下了MyEntity对象供进一步处理。