这篇blog主要和大家分享一下neo4j中是如何对节点进行遍历，和其中集成的图论的一些常用算法。

遍历

http://docs.neo4j.org.cn/tutorials-java-embedded-traversal.html? ?这是neo4j官方的中文教程。

?

private static Traverser getFriends(Node node )
{
    TraversalDescription td = Traversal.description()
            .breadthFirst()
            .relationships( RelTypes.KNOWS, Direction.OUTGOING )
            .evaluator( Evaluators.excludeStartPosition() );
    return td.traverse( node );
}

int num = 0;
String result = neoNode.getProperty( "name" ) + "'s friends:\n";
Traverser friendsTraverser = getFriends( neoNode );
for ( Path friendPath : friendsTraverser )
{
    output += "At depth " + friendPath.length() + " => "
              + friendPath.endNode()
                      .getProperty( "name" ) + "\n";
    numberOfFriends++;
}
output += "Number of friends found: " + numberOfFriends + "\n";

Thomas Anderson's friends:
At depth 1 => Trinity
At depth 1 => Morpheus
At depth 2 => Cypher
At depth 3 => Agent Smith
找到朋友的数量: 4

Node A = db.createNode();
Node B = db.createNode();
Node C = db.createNode();
Node D = db.createNode();
A.createRelationshipTo( B, REL1 );
B.createRelationshipTo( C, REL2 );
C.createRelationshipTo( D, REL3 );
A.createRelationshipTo( C, REL2 );

ArrayList<RelationshipType> orderedPathContext = new ArrayList<RelationshipType>();
orderedPathContext.add( REL1 );
orderedPathContext.add( withName( "REL2" ) );
orderedPathContext.add( withName( "REL3" ) );
TraversalDescription td = Traversal.description()
        .evaluator( new Evaluator()
        {