java - JGraph AWT EventQueue 绘画异常(多线程)

Question

情况

我有一个可视化使用 JGraph .该图由与实例化可视化的线程不同的线程更新。

预期行为

图形应由各种工作线程更新。线程调用以更新图形的函数是同步的，因此工作线程不会在它们之间引起并发问题。

实际行为

在绘制时(偶尔)在 AWT-EventQueue 线程中抛出异常。有时是空指针，有时是索引越界。这是堆栈跟踪:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at com.mxgraph.shape.mxConnectorShape.translatePoint(Unknown Source) at com.mxgraph.shape.mxConnectorShape.paintShape(Unknown Source) at com.mxgraph.canvas.mxGraphics2DCanvas.drawCell(Unknown Source) at com.mxgraph.view.mxGraph.drawState(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawCell(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawChildren(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawCell(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawChildren(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawCell(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawChildren(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawCell(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawFromRootCell(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.drawGraph(Unknown Source) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.paintComponent(Unknown Source) at javax.swing.JComponent.paint(JComponent.java:1029) at com.mxgraph.swing.mxGraphComponent$mxGraphControl.paint(Unknown Source) at javax.swing.JComponent.paintChildren(JComponent.java:866) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JViewport.paint(JViewport.java:764) at javax.swing.JComponent.paintToOffscreen(JComponent.java:5138) at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:302) at javax.swing.RepaintManager.paint(RepaintManager.java:1188) at javax.swing.JComponent._paintImmediately(JComponent.java:5086) at javax.swing.JComponent.paintImmediately(JComponent.java:4896) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:783) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:735) at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677) at javax.swing.RepaintManager.access$700(RepaintManager.java:58) at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1593) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:226) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:647) at java.awt.EventQueue.access$000(EventQueue.java:96) at java.awt.EventQueue$1.run(EventQueue.java:608) at java.awt.EventQueue$1.run(EventQueue.java:606) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105) at java.awt.EventQueue.dispatchEvent(EventQueue.java:617) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:200) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:185) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:177) at java.awt.EventDispatchThread.run(EventDispatchThread.java:138)

它似乎不会对应用程序的运行产生不利影响。一个新的 AWT-EventQueue 产生，它将在某个阶段不可避免地遇到同样的问题。

原因

我认为这一定是由于在单独的线程中将图形更新为实例化 JFrame 的线程引起的。需要绘制的东西在 paint 方法尝试绘制它们时发生了变化。

问题

我该如何解决这个问题？我能否以某种方式将绘制方法与更新图形的方法同步？

可视化代码

package ui;

import javax.swing.JFrame;

import com.mxgraph.layout.mxOrganicLayout;
import com.mxgraph.layout.mxStackLayout;
import com.mxgraph.model.mxCell;
import com.mxgraph.model.mxGraphModel;
import com.mxgraph.swing.mxGraphComponent;
import com.mxgraph.view.mxGraph;

import core.Container;
import core.Node;
import core.WarehouseGraph;

public class Visualisation extends JFrame{
    private static final long serialVersionUID = 8356615097419123193L;
    private mxGraph graph = new mxGraph();
    Object parent = graph.getDefaultParent();
    mxOrganicLayout graphlayout = new mxOrganicLayout(graph);
    mxStackLayout containerLayout = new mxStackLayout(graph, true, 10);

    public Visualisation(WarehouseGraph model){
        super("Warehouse Simulator");

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize(800, 600);

        graph.getModel().beginUpdate();
        try{
            for(Node node : model.getNodes().values()){
                mxCell cell = (mxCell)graph.insertVertex(parent, node.getId(), node.getId(), 0, 0, 60, 30);

                Object prev = null;
                for(Container container : node.getContainers()){
                    Object newCont = graph.insertVertex(cell, container.getId(), container.getId(), 0, 0, 60, 20);
                    if(prev != null) graph.insertEdge(cell, null, null, prev, newCont);
                    prev = newCont;
                }
            }

            for(Node node : model.getNodes().values()){
                for(Node toNode : node.getDownstreamNodes()){
                    Object fromCell = ((mxGraphModel)graph.getModel()).getCell(node.getId());
                    Object toCell = ((mxGraphModel)graph.getModel()).getCell(toNode.getId());
                    graph.insertEdge(parent, null, null, fromCell, toCell);
                }
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            graph.getModel().endUpdate();
        }

        graphlayout.execute(parent);

        Object[] nodes = mxGraphModel.getChildVertices(graph.getModel(), parent);
        for(Object cell : nodes){
            containerLayout.execute(cell);
            graph.updateCellSize(cell);
        }


        mxGraphComponent graphComponent = new mxGraphComponent(graph);
        getContentPane().add(graphComponent);

        this.setVisible(true);
    }

    //CALLED FROM SYNCHRONIZED FUNCTION
    public void moveContainer(Container container, Node to){
        graph.getModel().beginUpdate();
        mxCell toCell = (mxCell)((mxGraphModel)graph.getModel()).getCell(to.getId());
        mxCell containerCell = (mxCell)((mxGraphModel)graph.getModel()).getCell(container.getId());
        mxCell fromCell = (mxCell)containerCell.getParent();

        try{
            Object[] edges = mxGraphModel.getEdges(graph.getModel(), containerCell);
            graph.removeCells(edges);

            containerCell.removeFromParent();

            graph.addCell(containerCell, toCell);

            Object[] containers = mxGraphModel.getChildVertices(graph.getModel(), toCell);
            if(containers.length >= 2)
                graph.insertEdge(toCell, null, null, containerCell, containers[containers.length-2]);
            containerLayout.execute(toCell);
            containerLayout.execute(fromCell);
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            graph.getModel().endUpdate();
        }
    }
}

Controller 代码

package core;
import serialisation.JsonUtil;
import ui.Visualisation;

public class Controller{
    private WarehouseGraph graph;
    Visualisation viz;

    public static void main(String[] args){
        Controller.getInstance();
    }

    private Controller(){
        graph = JsonUtil.initFromJson(); //graph has many worker threads running which can call containerMoved
        viz = new Visualisation(graph);
    }

    private static class SingletonHolder{
        private static final Controller INSTANCE = new Controller();
    }

    public static Controller getInstance(){
        return SingletonHolder.INSTANCE;
    }

    public synchronized void containerMoved(Container container, Node from, Node to){
        viz.moveContainer(container, to);
    }
}

Answer 1

不是回答你的问题，只是对你的概念的一些通知。

1. 您能向我们展示您的public static void main(String[] args) {...} 方法吗？我希望有一些东西看起来像:

   public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() {

           public void run() {
               Visualisation vis = new Visualisation();
           }
       });
   }
   

2. this.setSize(800, 600); 应该是 this.setpreferredSize(new Dimension(800, 600));

   <

3. 然后在最后一行之前添加this.pack(); (this.setVisible(true);)

编辑:

1. 什么类型的组件返回 mxGraphComponent graphComponent = new mxGraphComponent(graph); 因为如果是基于 JPanel 的自定义组件那么

getContentPane().add(graphComponent); 应该是 add(graphComponent);

1. 来自后台线程/任务的所有输入都必须包装到 invokeLater() 中.如果它闪烁或卡住，那么您必须寻找 invokeAndWait()。我个人讨厌那里存在invokeAndWait()，但是对于这个方法我不能给你一些正确的建议。或者:

2. 如果您将在某些周期性基础上运行您的任务，那么您必须寻找 Runnable(输出必须包装到 invokeLater 中)或 SwingWorker .