我从以下链接中得出了答案:

I figured this out from the below link:

https://www .daniweb.com/software-development/java/threads/386037/different-height-of-jtree-nodes

本质上，所需要做的就是将行高设置为0，以使叶节点高度可变，这取决于要渲染的组件，而不是固定的(我认为)默认值.

In essence, all that is needed to do is set the row height to 0 to make the leaf node height variable, depending on the component being rendered as opposed to a fixed (I presume) default value.

因此，代码如下所示:

JTree tree = new JTree(root);
tree.setRowHeight(0);
tree.setCellRenderer(new ExampleRenderer());

结果是这样的: