package neo4j;

import java.io.File;
import java.io.IOException;

import javax.management.relation.Relation;

import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
import org.neo4j.io.fs.FileUtils;

public class test {


 public enum RelTypes implements RelationshipType{
  KNOWS
 }

 private static void registerShutdownHook( final GraphDatabaseService graphDb )
 {
  // Registers a shutdown hook for the Neo4j instance so that it
  // shuts down nicely when the VM exits (even if you "Ctrl-C" the
  // running example before it's completed)
  /*為了確保neo4j數(shù)據(jù)庫(kù)的正確關(guān)閉，我們可以添加一個(gè)關(guān)閉鉤子方法
   * registerShutdownHook。這個(gè)方法的意思就是在jvm中增加一個(gè)關(guān)閉的
   * 鉤子，當(dāng)jvm關(guān)閉的時(shí)候，會(huì)執(zhí)行系統(tǒng)中已經(jīng)設(shè)置的所有通過方法
   * addShutdownHook添加的鉤子，當(dāng)系統(tǒng)執(zhí)行完這些鉤子后，jvm才會(huì)關(guān)閉。
   * 所以這些鉤子可以在jvm關(guān)閉的時(shí)候進(jìn)行內(nèi)存清理、對(duì)象銷毀等操作。*/
  Runtime.getRuntime().addShutdownHook( new Thread()
  {
   @Override
   public void run()
   {
    graphDb.shutdown();
   }
  } );
 }

 public static void main(String[] args) throws IOException {

  FileUtils.deleteRecursively( new File( "db" ) ); 
  GraphDatabaseService graphdb=new GraphDatabaseFactory().newEmbeddedDatabase("db");
  Relationship relationship;
  Transaction tx=graphdb.beginTx();
  try{
   Node node1=graphdb.createNode();
   Node node2=graphdb.createNode();

   node1.setProperty("message", "Hello");
   node2.setProperty("message", "World");

   relationship = node1.createRelationshipTo(node2, RelTypes.KNOWS);
   relationship.setProperty("message", "brave neo4j");


   tx.success();
   System.out.println("successfully");
  }
  finally{
   tx.finish();
  }
  registerShutdownHook(graphdb);
 }

}