JTree 设置选中行整行的背景色

朱雀 2024-04-07 14:43 95阅读 0赞

#### JTree 设置选中行整行的背景色 ####

*  1.需求描述
 *  2.代码实现
 *  3.效果演示

> 系统：Win10  
> JDK：1.8.0\_333  
> IDEA：2020.3.4

## 1.需求描述 ##

在写一个 Swing 项目的时候，发现 JTree 树节点在选中时，只显示节点的背景色，不会改变整行的颜色，这样有些不太明显且不好看，所以我需要实现在点击该行时，整行的背景色都发生改变，最好在失去焦点时，选中行的颜色能进行变化

## 2.代码实现 ##

public class MyTree extends JTree {
        
        private static final Color HFC = new Color(205, 232, 255); // 获取焦点时的颜色
        private static final Color LFC = new Color(213, 213, 213); // 失去焦点时的颜色
        private Handler handler;
    
        @Override
        protected void paintComponent(Graphics g) {
        
            g.setColor(getBackground());
            g.fillRect(0, 0, getWidth(), getHeight());
            // 根据焦点状态绘制树节点整行的颜色
            if (getSelectionCount() > 0) {
        
                if (hasFocus()) {
        
                    g.setColor(HFC);
                } else {
        
                    g.setColor(LFC);
                }
                for (int i : getSelectionRows()) {
        
                    Rectangle r = getRowBounds(i);
                    g.fillRect(0, r.y, getWidth(), r.height);
                }
            }
            super.paintComponent(g);
        }
    
        @Override
        public void updateUI() {
        
            removeFocusListener(handler);
            super.updateUI();
            setUI(new BasicTreeUI() {
        
                @Override
                public Rectangle getPathBounds(JTree tree, TreePath path) {
        
                    if (tree != null && treeState != null) {
        
                        return getPathBounds(path, tree.getInsets(), new Rectangle());
                    }
                    return null;
                }
    
                private Rectangle getPathBounds(
                        TreePath path, Insets insets, Rectangle bounds) {
        
                    Rectangle rect = treeState.getBounds(path, bounds);
                    if (rect != null) {
        
                        rect.width = tree.getWidth();
                        rect.y += insets.top;
                    }
                    return rect;
                }
            });
            handler = new Handler();
            addFocusListener(handler);
            setCellRenderer(handler);
            setOpaque(false);
        }
    
        static class Handler extends DefaultTreeCellRenderer implements FocusListener {
        
            @Override
            public Component getTreeCellRendererComponent(
                    JTree tree, Object value, boolean selected, boolean expanded,
                    boolean leaf, int row, boolean hasFocus) {
        
                JLabel label = (JLabel) super.getTreeCellRendererComponent(
                        tree, value, selected, expanded, leaf, row, hasFocus);
                // 根据焦点状态设置不同的背景色
                if (hasFocus) {
        
                    label.setBackground(selected ? HFC : tree.getBackground());
                } else {
        
                    label.setBackground(selected ? LFC : tree.getBackground());
                }
                label.setOpaque(true);
                return label;
            }
    
            @Override
            public void focusGained(FocusEvent e) {
        
                e.getComponent().repaint();
            }
    
            @Override
            public void focusLost(FocusEvent e) {
        
                e.getComponent().repaint();
            }
        }
    
        public static void main(String[] args) {
        
            JFrame frame = new JFrame();
            frame.setTitle("MyTree Test"); // 设置标题
            frame.setSize(600, 500); // 设置大小
            JSplitPane splitPane = new JSplitPane();
            splitPane.setDividerLocation(150); // 设置分隔线位置
            JScrollPane scrollPane = new JScrollPane();
            MyTree tree = new MyTree(); // 创建一个树
            scrollPane.setViewportView(tree);
            splitPane.setLeftComponent(scrollPane);
            splitPane.setRightComponent(new JScrollPane(new JTextArea()));
            frame.add(splitPane);
            frame.setLocationRelativeTo(null); // 居中
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 设置默认关闭操作
            frame.setVisible(true); // 设置可见
        }
    }

## 3.效果演示 ##

![请添加图片描述][eabc37a42b28410cb1108bc55926e476.gif]

[eabc37a42b28410cb1108bc55926e476.gif]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/74fd22d514694cb58767a35165e4f13a.gif