如何有效地完全扩展大型JTree

Question

如何有效地完全扩展大型JTree

Mar*_*o13 1 java performance swing jtree

有几个相关的问题,关于在设置新的TreeModel时自动扩展JTree,或者关于扩展JTree的一般问题,其中一些也是针对在JTree中扩展许多路径的性能.

但是,所提出的解决方案似乎都没有涵盖人们可以考虑的"简单"应用案例:我有一棵大树(也就是说,树很深,很宽,或两者兼而有之),我想完全以编程方式扩展它.

以下是显示问题的MCVE:它创建一个具有100k节点的树模型.按下按钮会触发调用expandAll,该调用尝试使用从相关问题的答案派生的方法扩展所有节点.

问题是扩展这些100k节点需要大约13秒(在普通机器上,使用最近的JVM).

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.util.function.Consumer;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeModel;


public class TreeExpansionPerformanceProblem
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(
            () -> createAndShowGUI());
    }

    private static void createAndShowGUI()
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().setLayout(new GridLayout(1,0));

        f.getContentPane().add(createTestPanel(
            TreeExpansionPerformanceProblem::expandAll));

        f.setSize(800,600);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static JPanel createTestPanel(Consumer<JTree> expansionMethod)
    {
        JPanel panel = new JPanel(new BorderLayout());
        JTree tree = new JTree(createTestTreeModel());
        panel.add(new JScrollPane(tree), BorderLayout.CENTER);

        JPanel buttonPanel = new JPanel();
        JButton expandAllButton = new JButton("Expand all");
        expandAllButton.addActionListener( e -> 
        {
            System.out.println("Expanding...");
            long before = System.nanoTime();
            expansionMethod.accept(tree);
            long after = System.nanoTime();
            System.out.println("Expanding took "+(after-before)/1e6);

        });
        buttonPanel.add(expandAllButton);
        panel.add(buttonPanel, BorderLayout.SOUTH);
        return panel;
    }

    private static void expandAll(JTree tree)
    {
        int r = 0;
        while (r < tree.getRowCount())
        {
            tree.expandRow(r);
            r++;
        }
    }

    private static TreeModel createTestTreeModel() 
    {
        DefaultMutableTreeNode root = new DefaultMutableTreeNode("JTree");
        addNodes(root, 0, 6, 6, 10);
        return new DefaultTreeModel(root);
    }

    private static void addNodes(DefaultMutableTreeNode node, 
        int depth, int maxDepth, int count, int leafCount)
    {
        if (depth == maxDepth)
        {
            return;
        }
        for (int i=0; i<leafCount; i++)
        {
            DefaultMutableTreeNode leaf = 
                new DefaultMutableTreeNode("depth_"+depth+"_leaf_"+i);
            node.add(leaf);
        }
        if (depth < maxDepth - 1)
        {
            for (int i=0; i<count; i++)
            {
                DefaultMutableTreeNode child = 
                    new DefaultMutableTreeNode("depth_"+depth+"_node_"+i);
                node.add(child);
                addNodes(child, depth+1, maxDepth, count, leafCount);
            }
        }

    }
}

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是否有任何选项可以更有效地扩展许多节点？

Answer 1

Mar*_*o13 7

完全扩展大树时存在各种瓶颈,以及绕过这些瓶子的不同方法.

有趣的是,收集TreePath扩展和遍历树的对象通常不是最昂贵的部分.根据VisualVM和Java Flight Recorder中的分析器运行,大多数时间用于计算模型状态(the TreeModel)和视图(the JTree)之间的"映射" .这主要是指

计算行的高度 JTree
计算标签中的标签边界 TreeCellRenderer

并非所有这些计算都可以避免.但是,通过以下方式可以显着提高树的扩展速度

设置固定的行高,用 JTree#setRowHeight
暂时禁用TreeExpansionListeners树

以下是一个MCVE,它比较了问题中的"天真"方法(用于将具有100k节点的树扩展为13秒)到稍微更快的方法,只需要1秒来扩展同一棵树.

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.GridLayout;
import java.util.Arrays;
import java.util.List;
import java.util.function.Consumer;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.event.TreeExpansionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeCellRenderer;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;


public class TreeExpansionPerformanceSolution
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(
            () -> createAndShowGUI());
    }

    private static void createAndShowGUI()
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().setLayout(new GridLayout(1,0));

        f.getContentPane().add(createTestPanel(
            TreeExpansionPerformanceSolution::expandAll));

        f.getContentPane().add(createTestPanel(
            TreeExpansionPerformanceSolution::expandAllFaster));

        f.setSize(800,600);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static JPanel createTestPanel(Consumer<JTree> expansionMethod)
    {
        JPanel panel = new JPanel(new BorderLayout());
        JTree tree = new JTree(createTestTreeModel());
        panel.add(new JScrollPane(tree), BorderLayout.CENTER);

        JPanel buttonPanel = new JPanel();
        JButton expandAllButton = new JButton("Expand all");
        expandAllButton.addActionListener( e -> 
        {
            System.out.println("Expanding...");
            long before = System.nanoTime();
            expansionMethod.accept(tree);
            long after = System.nanoTime();
            System.out.println("Expanding took "+(after-before)/1e6);

        });
        buttonPanel.add(expandAllButton);
        panel.add(buttonPanel, BorderLayout.SOUTH);
        return panel;
    }

    private static void expandAll(JTree tree)
    {
        int r = 0;
        while (r < tree.getRowCount())
        {
            tree.expandRow(r);
            r++;
        }
    }

    private static void expandAllFaster(JTree tree)
    {
        // Determine a suitable row height for the tree, based on the 
        // size of the component that is used for rendering the root 
        TreeCellRenderer cellRenderer = tree.getCellRenderer();
        Component treeCellRendererComponent = 
            cellRenderer.getTreeCellRendererComponent(
                tree, tree.getModel().getRoot(), false, false, false, 1, false);
        int rowHeight = treeCellRendererComponent.getPreferredSize().height + 2;
        tree.setRowHeight(rowHeight);

        // Temporarily remove all listeners that would otherwise
        // be flooded with TreeExpansionEvents
        List<TreeExpansionListener> expansionListeners =
            Arrays.asList(tree.getTreeExpansionListeners());
        for (TreeExpansionListener expansionListener : expansionListeners)
        {
            tree.removeTreeExpansionListener(expansionListener);
        }

        // Recursively expand all nodes of the tree
        TreePath rootPath = new TreePath(tree.getModel().getRoot());
        expandAllRecursively(tree, rootPath);

        // Restore the listeners that the tree originally had
        for (TreeExpansionListener expansionListener : expansionListeners)
        {
            tree.addTreeExpansionListener(expansionListener);
        }

        // Trigger an update for the TreeExpansionListeners
        tree.collapsePath(rootPath);
        tree.expandPath(rootPath);
    }

    // Recursively expand the given path and its child paths in the given tree
    private static void expandAllRecursively(JTree tree, TreePath treePath)
    {
        TreeModel model = tree.getModel();
        Object lastPathComponent = treePath.getLastPathComponent();
        int childCount = model.getChildCount(lastPathComponent);
        if (childCount == 0)
        {
            return;
        }
        tree.expandPath(treePath);
        for (int i=0; i<childCount; i++)
        {
            Object child = model.getChild(lastPathComponent, i);
            int grandChildCount = model.getChildCount(child);
            if (grandChildCount > 0)
            {
                class LocalTreePath extends TreePath
                {
                    private static final long serialVersionUID = 0;
                    public LocalTreePath(
                        TreePath parent, Object lastPathComponent)
                    {
                        super(parent, lastPathComponent);
                    }
                }
                TreePath nextTreePath = new LocalTreePath(treePath, child);
                expandAllRecursively(tree, nextTreePath);
            }
        }
    }


    private static TreeModel createTestTreeModel() 
    {
        DefaultMutableTreeNode root = new DefaultMutableTreeNode("JTree");
        addNodes(root, 0, 6, 6, 10);
        return new DefaultTreeModel(root);
    }

    private static void addNodes(DefaultMutableTreeNode node, 
        int depth, int maxDepth, int count, int leafCount)
    {
        if (depth == maxDepth)
        {
            return;
        }
        for (int i=0; i<leafCount; i++)
        {
            DefaultMutableTreeNode leaf = 
                new DefaultMutableTreeNode("depth_"+depth+"_leaf_"+i);
            node.add(leaf);
        }
        if (depth < maxDepth - 1)
        {
            for (int i=0; i<count; i++)
            {
                DefaultMutableTreeNode child = 
                    new DefaultMutableTreeNode("depth_"+depth+"_node_"+i);
                node.add(child);
                addNodes(child, depth+1, maxDepth, count, leafCount);
            }
        }

    }
}

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笔记:

这是一个自我回答的问题,我希望这个答案可能对其他人有所帮助.尽管如此,1秒仍然相当缓慢.我尝试了其他一些东西,例如设置tree.setLargeModel(true),但这没有产生积极的影响(事实上,它甚至更慢!).大部分时间仍然花在树的视觉状态的最终更新上,我很高兴看到这里有进一步的改进.
该expandAllRecursively方法可以通过包括几行字来代替DefaultMutableTreeNode#breadthFirstEnumeration,并DefaultTreeModel#getPathToRoot在不牺牲太多性能.但在当前形式中,代码仅在TreeModel接口上运行,并且应该适用于任何类型的节点.

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