Question

我是Neo4j Graph Database的新手，我想从java Application创建CyperQueries。我正在使用上面的neo4j手册

http://docs.neo4j.org/chunked/milestone/query-create.html

我正在从java APplication创建节点，如下所示

public class CreateQuery
{
    public static final String DBPATH="D:/Neo4j/CQL";

    public static void main(String args[])
    {
        GraphDatabaseService path=new EmbeddedGraphDatabase(DBPATH);
        Transaction tx=path.beginTx();
        try
        {
        Map<String, Object> props  = new HashMap<String, Object>();
        props .put( "Firstnamename", "Sharon" );
        props .put( "lastname", "Eunis" );

        Map<String, Object> params = new HashMap<String, Object>();
        params.put( "props", props  );

        ExecutionEngine engine=new ExecutionEngine(path);
        ExecutionResult result=engine.execute( "create ({props})", params );
        System.out.println(result);
        tx.success();
        } 
        finally
        {
             tx.finish();
             path.shutdown();

        }
    }
}

我收到了上述错误。我不知道这个错误，请尽快帮助解决。

Exception in thread "main" java.lang.NoClassDefFoundError: com/googlecode/concurrentlinkedhashmap/ConcurrentLinkedHashMap$Builder
    at org.neo4j.cypher.internal.LRUCache.<init>(LRUCache.scala:30)
    at org.neo4j.cypher.ExecutionEngine$$anon$1.<init>(ExecutionEngine.scala:84)
    at org.neo4j.cypher.ExecutionEngine.<init>(ExecutionEngine.scala:84)
    at com.neo4j.CreateQuery.main(CretaeQuery.java:33)
Caused by: java.lang.ClassNotFoundException: com.googlecode.concurrentlinkedhashmap.ConcurrentLinkedHashMap$Builder
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 4 more

Answer 1

您可能需要添加此库的最新版本（ConcurrentLinkedHashMap for Java）：

http://concurrentlinkedhashmap.googlecode.com/files/concurrentlinkedhashmap-lru-1.3.1.jar

Answer 2

您共享的代码运行正常。我认为问题在于你的import语句。它们应该是这样的：

import java.util.HashMap;
import java.util.Map;
import org.neo4j.cypher.javacompat.ExecutionEngine;
import org.neo4j.cypher.javacompat.ExecutionResult;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Transaction;
import org.neo4j.kernel.EmbeddedGraphDatabase;

Answer 3

看起来像是库错误。也许你输入了错误版本的东西？

为了以防万一，我应该指出你是打算使用GDB工厂来构建一个嵌入式实例：

graphDb = new GraphDatabaseFactory().newEmbeddedDatabase(DB_PATH);

不确定它会有什么不同。

Java应用程序中执行Neo4j的Cypher查询的异常

3 个答案: