java - 如何将 JTree“ctrl”选择模式设置为始终启用

Question

我有一个实现多选逻辑的 JTree。

当我使用鼠标 + Ctrl 键进行所有选择时，这非常有用。如果用户在未按下 Ctrl 键的情况下进行选择，则会破坏我的逻辑。

我真的不明白它为什么会中断，但我认为一个可能的解决方案是始终指示 TreeSelectionModel 已按下 Ctrl 键进行选择。

你有什么建议？

Answer 1

我想我找到了解决方案

您将需要扩展 JTree 和 DefaultTreeSelectionModel。

JTree相关方法：

/////////////////////////////////////////////////////
/////////////////////////////////////////////////////
/// Implement selection using "adding" only logic. //
/////////////////////////////////////////////////////
/////////////////////////////////////////////////////

@Override
public void setSelectionPath(TreePath path) {

    System.out.println("MLDebugJTree: setSelectionPath(" + path + ")");

    addSelectionPath(path);

    return;
    //super.setSelectionPath(path);
}

@Override
public void setSelectionPaths(TreePath[] paths) {

    System.out.println("MLDebugJTree: setSelectionPaths(" + paths + ")");

    addSelectionPaths(paths);

    return;
}

@Override
public void setSelectionRow(int row) {

    System.out.println("MLDebugJTree: setSelectionRow(" + row + ")");

    addSelectionRow(row);

    return;
    //super.setSelectionRow(row);
}

@Override
public void setSelectionRows(int[] rows) {

    System.out.println("MLDebugJTree: setSelectionRows(" + rows + ")");

    addSelectionRows(rows);

    return;
    //super.setSelectionRows(rows);
}

DefaultSelectionModel 相关方法：

package com.ml.tree2.model.impl;

import javax.swing.tree.DefaultTreeSelectionModel;
import javax.swing.tree.TreePath;

public class MLTreeSelectionModel extends DefaultTreeSelectionModel {
private static final long serialVersionUID = -4270031800448415780L;

@Override
public void addSelectionPath(TreePath path) {
    // Don't do overriding logic here because addSelectionPaths is ultimately called.
    super.addSelectionPath(path);
}

@Override
public void addSelectionPaths(TreePath[] paths) {
    if(paths != null) {
        for(TreePath path : paths) {

            TreePath[] toAdd = new TreePath[1];
            toAdd[0] = path;

            if (isPathSelected(path)) {
                // If path has been previously selected REMOVE THE SELECTION.
                super.removeSelectionPaths(toAdd);
            } else {
                // Else we really want to add the selection...
                super.addSelectionPaths(toAdd);
            }
        }
    }
}

HTH。

Answer 2

另一种解决方案是简单地扩展 BasicTreeUI 并更改选择行为以满足您的需求：

public class MultiSelectionTreeUI extends BasicTreeUI
{

    @Override
    protected boolean isToggleSelectionEvent( MouseEvent event )
    {
        return SwingUtilities.isLeftMouseButton( event );
    }
}

然后在您的 JTree 上设置该 ui：

JTree tree = new JTree();
tree.setUI( new MultiSelectionTreeUI() );