Java ng

如果您向我们展示了代码的其余部分，其中循环调用查询300次，我们可能会进一步提供帮助

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一般来说，如果你每次都在计算最短路径，那么你应该建立一个类似网格的表格，为每个站点预先计算路线距离，甚至从每个站点预先计算整个路线。

谢谢你的回答。是的，我有一个以站点为节点的图表。我已经用我正在使用的方法的完整代码更新了这个问题。getNeights（）方法通过PriorityQueue传递给具有最低值（（到达节点的成本）+（到目标节点的距离））的节点。这就是为什么每次数据库是优先级队列顶部的新节点时，我都必须查询数据库的原因。我无法预测下一个节点将是优先级队列中的第一个节点，直到我访问相邻节点。我无法缓存停止连接数据，因为它包含10000多个连接。有什么建议吗？不要使用DB。将所有数据加载到主内存中的“图形”对象。在我的项目中，我有数百万个节点（甚至更多的边）在图中，还有一些Dijkstra算法在所有这些节点上运行，我得到的运行时间远远少于一秒钟。这个JDBC代码正在泄漏资源。尽快修复。感谢我将所有连接数据缓存在一个哈希表中，这防止了我继续连接到数据库

private HashMap<Coordinate,Node> closedNodes;
private PriorityQueue<Node> openNodes;

..
private List<Coordinate> calculatePath() 
{
    //While there are nodes in the open list
    while (!openNodes.isEmpty()) 
    {
        //Get the node with the lowest gVal+hVal
        Node node = openNodes.poll();
        //Add it to the closed list
        closedNodes.put(node);
        //If it is not the goal node
        if (!node.equals(goal)) 
        {   
            //Get all the neighbours and Create neighbour node
            List<Node> neighbours = helper.getNeighbours(node, goal);
            //For each neighbour
            for (Node neighbourNode : neighbours) 
            {
                //Check if the neighbour is in the list of open nodes
                boolean isInOpen = checkOpenNodes(neighbourNode);
                //If it is not in the open nodes and not in the closed nodes
                if ((!closedNodes.containsKey(neighbourNode))&& (!isInOpen)) 
                {
                    //Add it to the list of open nodes
                    openNodes.add(neighbourNode);
                }
            }
        }
        else 
        {
            // We found the path
            path = backTrackPath(node);
            break;              
        }
    }
    return path;

/**
 * Gets the list of valid Nodes that are possible to travel to from <b>Node</b>
 * @param stopNode Node to find neighbours for
 * @param goal End Node
 * @return list of neighbour Nodes
 */
public ArrayList<Node> getNeighbours(Node stopNode, Node goal) 
{
    ArrayList<Node> neighbours = new ArrayList<Node>(); 
    Node neighbourNode;     
    //get neighbours connected to stop  
        try {
            ResultSet rs = stmt.executeQuery("select To_Station_id, To_Station_routeID, To_Station_stopID," +
                    "To_Station_lat, To_Station_lng, Time from connections  where Connections.From_Station_stopID ="
                    +stopNode.getCoord().getStopID()+" ORDER BY Connections.Time");

            rs = stmt.getResultSet();
            while (rs.next()) {
                int id = rs.getInt("To_Station_id");
                String routeID = rs.getString("To_Station_routeID");
                String stopID = rs.getString("To_Station_stopID");
                String stopName = rs.getString("To_Station_stopName");
                Double lat = rs.getDouble("To_Station_lat");
                Double lng = rs.getDouble("To_Station_lng");
                int time = rs.getInt("Time");
                neighbourNode = new Node(id, routeID, stopID, stopName, lat, lng);
                neighbourNode.prev = stopNode;
                neighbourNode.gVal = stopNode.gVal + time;
                neighbourNode.hVal = heuristic.calculateHeuristic(neighbourNode, goal);
                neighbours.add(neighbourNode);
            }
        }
    catch (SQLException e) {
        e.printStackTrace();
    }
    return neighbours;
}