在java应用程序中查询Neo4j

Question

我在java应用程序中使用Neo4j。如何计算数据库中的所有节点并在屏幕上打印？任何人都可以帮助我吗？

    package pesquisaBanco;

import org.neo4j.graphdb.GraphDatabaseService;
//import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;

public class pesquisar {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        GraphDatabaseService graphDb = new GraphDatabaseFactory()
                .newEmbeddedDatabase("C:/Users/Jessica/neo4j");
        Transaction transaction;
        transaction = graphDb.beginTx();

        //QUERY HERE!

        transaction.success();
        transaction.close();

    }

}

Answer 1

您可以使用Cypher COUNT aggregation function进行查询： MATCH n RETURN count(n) AS count。

由AS定义的别名就是为了让以下columnAs更容易。

请注意，最佳做法是将交易包装在try-with-resources块中，例如：

ExecutionEngine engine = new ExecutionEngine(graphDb);
try (Transaction transaction= graphDb.beginTx();
     ResourceIterator<Long> results = engine.execute("MATCH n RETURN count(n) AS count").columnAs("count")) {

   System.out.println(results.next());
   transaction.success();
}