Question

我使用Neo4j图形数据库和java的Neo4j Cypher api来获取查询结果。转储到字符串方法将以字符串格式给出执行结果。

  GraphDatabaseFactory graphDbFactory = new GraphDatabaseFactory();

  GraphDatabaseService graphDb = graphDbFactory.newEmbeddedDatabase("C:/TPNeo4jDB");

  ExecutionEngine execEngine = new ExecutionEngine(graphDb);
  ExecutionResult execResult = execEngine.execute("MATCH (java:JAVA) RETURN java");
  String results = execResult.dumpToString();
  System.out.println(results);

输出字符串将如下所示。

 +--------------------------+
 | a                        |
 +--------------------------+
 | Node[12]{type:"java 1"} |
 | Node[13]{type:"java 2"} |
 +--------------------------+
 2 rows

是否有任何默认的apis以通用的方式解析它？

根据我已经完成的答案

ExecutionResult execResult = execEngine.execute("MATCH (java:JAVA) RETURN java");
    Iterator<Node> n_column = execResult2.columnAs( "java" );
    for ( Node node : IteratorUtil.asIterable( n_column ) )
    {
        // note: we're grabbing the name property from the node,
        // not from the n.name in this case.
       String nodeResult = node + ": " + node.getProperty( "type" );
       System.out.println("noderesult :"+nodeResult);
    }

它给出了引发异常的第一个值的结果。如何解决这个问题？

noderesult :Node[12]: java 1

Jun 12, 2015 7:21:03 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [dispatcher] in context with path     [/BOSBOT] threw exception [Request processing failed; nested exception is     org.neo4j.graphdb.NotInTransactionException] with root cause
org.neo4j.graphdb.NotInTransactionException
at org.neo4j.kernel.impl.core.ThreadToStatementContextBridge.assertInUnterminatedTransaction(ThreadToStatementContextBridge.java:71)
at org.neo4j.kernel.impl.core.ThreadToStatementContextBridge.getTopLevelTransactionBoundToThisThread(ThreadToStatementContextBridge.java:104)
at org.neo4j.kernel.impl.core.ThreadToStatementContextBridge.getKernelTransactionBoundToThisThread(ThreadToStatementContextBridge.java:111)
at org.neo4j.kernel.impl.core.ThreadToStatementContextBridge.get(ThreadToStatementContextBridge.java:64)
at org.neo4j.kernel.InternalAbstractGraphDatabase$8.statement(InternalAbstractGraphDatabase.java:748)
at org.neo4j.kernel.impl.core.NodeProxy.getProperty(NodeProxy.java:387)

Answer 1

是的，你可以这样做：

Iterator<Node> javaNodes = execResult.columnAs( "java");
for (Node node : IteratorUtil.asIterable(javaNodes))
{
    //do something with the node
}

详细介绍了包含许多列时要执行的操作的详细信息 http://neo4j.com/docs/2.1.8/tutorials-cypher-java.html

根据评论更新：

Cypher查询为MATCH (java:Java) return java，因此列名称为java，该列中返回的值为Node。

如果您想要type属性，那么查询将为MATCH (java:Java) return java.type as type，然后您可以执行columnAs("type")。此列的类型现在是String。

在java中解析Neo4j ExecutionResult dumptoString

1 个答案: