Question

当我尝试使用DataStax Java Driver从Java连接到Cassandra时，我收到此错误。关于SO我几乎没有回答。 Here它在Guava 19.0中显示com.google.common.util.concurrent.FutureFallback is deprecated并从Guava 20.0开始删除。因此，不要使用Guava 20.0或更高版本。

此外，我正在使用需要Guava 20.0的Pmml-Evaluator。如果我删除连接到Cassandra的代码，我的代码工作正常。那么，我现在如何解决这个问题？

Pom.xml依赖项：

<dependencies>

    <dependency>
      <groupId>org.jpmml</groupId>
      <artifactId>pmml-model</artifactId>
      <version>1.3.4</version>
   </dependency>

     <dependency>
        <groupId>com.beust</groupId>
        <artifactId>jcommander</artifactId>
        <version>1.48</version>
      </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>

     <dependency>
        <groupId>org.jpmml</groupId>
        <artifactId>pmml-evaluator</artifactId>
        <version>1.3.4</version>
      </dependency>

   <dependency>
      <groupId>io.grpc</groupId>
      <artifactId>grpc-netty</artifactId>
      <version>1.1.2</version>
    </dependency>

  <dependency>
    <groupId>io.grpc</groupId>
    <artifactId>grpc-protobuf</artifactId>
    <version>1.1.2</version>
  </dependency>

  <dependency>
    <groupId>io.grpc</groupId>
    <artifactId>grpc-stub</artifactId>
    <version>1.1.2</version>
  </dependency>

  <dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-handler</artifactId>
    <version>4.1.8.Final</version>
</dependency>

  <dependency>
      <groupId>com.datastax.cassandra</groupId>
      <artifactId>cassandra-driver-core</artifactId>
      <version>3.1.4</version>
  </dependency>

  </dependencies>

上课：

package com.cw.predictive;

import com.datastax.driver.core.Session;
import com.datastax.driver.core.Cluster;

public class CassandraSession {

    private static Session session;

    private CassandraSession(){}

    public static Session getCassandraSessionInstance(String[] CONTACT_POINTS, int PORT){

        if(session == null){                    
            synchronized (Session.class) {
                if(session == null){                   
                    try{                                        
                         Cluster cluster = Cluster.builder()
                        .addContactPoints(CONTACT_POINTS).withPort(PORT)
                        .build();                                              
                         session = cluster.connect();
                    }
                    catch(Exception ex) {
                        System.out.println("Error occurred");
                        return null;            
                    }               
                }             
            }           
        }       
        return session;
    }
}

错误：

Exception in thread "grpc-default-executor-0" java.lang.NoClassDefFoundError: com/google/common/util/concurrent/FutureFallback
        at com.cw.predictive.CassandraSession.getCassandraSessionInstance(CassandraSession.java:18)
        at com.cw.predictive.PredictiveScore$LeadScoreImpl.getLeadScore(PredictiveScore.java:136)
        at com.cw.predicitivegrpc.LeadScoreGrpc$MethodHandlers.invoke(LeadScoreGrpc.java:234)
        at io.grpc.stub.ServerCalls$1$1.onHalfClose(ServerCalls.java:148)
        at io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:263)
        at io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$2.runInContext(ServerImpl.java:586)
        at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:52)
        at io.grpc.internal.SerializingExecutor$TaskRunner.run(SerializingExecutor.java:152)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: java.lang.ClassNotFoundException: com.google.common.util.concurrent.FutureFallback
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        ... 11 more

Answer 1

正如您所遇到的，Apache Cassandra的DataStax Java驱动程序尚不支持Guava 20和21（请参阅：JAVA-1328）。

但是，有一个working PR已针对Guava 16.01,17.0,18.0,19.0,20.0和21.0进行了测试，我们针对此修复程序定位了3.2.0版本。

我刚刚注意到您共享的pmml-evaluator的pom.xml显示了支持的版本范围[14.0, 20.0]：

<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>[14.0, 20.0]</version>
</dependency>

你可以做的是将guava排除为org.jpmml中的依赖项，即：

<dependency>
  <groupId>org.jpmml</groupId>
  <artifactId>pmml-evaluator</artifactId>
  <version>1.3.4</version>
  <exclusions>
    <exclusion>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
    </exclusion>
  </exclusions>
</dependency>

这样可以防止guava 20.0因为解析pmml-evaluator的依赖而被拉入，而番石榴16.01将通过java驱动程序的传递依赖而被拉入。

找不到类com / google / common / util / concurrent / FutureFallback

1 个答案: