JTree像QQ一样显示图片

来源：互联网发布：药智数据库会员编辑：程序博客网时间：2024/05/03 03:30

要想JTree显示带图片的节点，其目的就是改变JTree的渲染器，也就是调用JTree中setCellRenderer（TreeCellRenderer x），而默认的DefaultTreeCellRenderer没有这个功能，于是我就去继承这个类并重写它的getTreeCellRendererComponent方法，示例如下：

步骤一，继承DefaultTreeCellRenderer类并重写方法(当然这一步可以写在最后)：

import java.awt.Component;import javax.swing.Icon;import javax.swing.JTree;import javax.swing.tree.DefaultTreeCellRenderer;public class IconNodeRendereer extends DefaultTreeCellRenderer {private static final long serialVersionUID = -3494723715969483744L;//下面这个方法重写请自己查看API各个参数的意思public Component getTreeCellRendererComponent(JTree tree, Object value,boolean sel, boolean expanded, boolean leaf, int row,boolean hasFocus) {super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf,row, hasFocus);               //IconTreeNode是重写的继承DefaultMutableTreeNode的带图片的节点Icon icon = ((IconTreeNode) value).getIcon();              //StringValue是value调用toString()后的转来的描述性文字，所以在节点中包装的对象应自己重写toString方法来实现自己想要的结果String stringValue = tree.convertValueToText(value, sel, expanded, leaf, row, hasFocus);//为什么可以设置图片和文字？因为DefaultTreeCellRenderer继承了JLabel它的渲染结果就是可以显示图片和文字，当然如果自己想要也可以显示超链接（这个在此不描述，后来再补上在JLabel上实现超链接）setText(stringValue);  setIcon(icon);return this;}//end of getTreeCellRendererComponent}

步骤二：节点封装对象的描写

public class User {private String name;private Icon icon;//ImageManager是我自己写的一个用来获取Icon的类，这个你可以不管，只要穿进去的参数是Icon就可以了public static final Icon defaultIcon = ImageManager.getIcon("Cat.png");public User( String name, Icon icon) {super();this.name = name;this.icon = icon;}public User(String name){//对于没有传Icon的就赋予默认Iconthis(name,defaultIcon);} public String toString() {//重写自己的toString方法//由于TreeCellRenderer extends JLabel所以可以使用html标签用来修饰，以至于在JTree中显示自己预设文字的效果return "<html><br/><strong><font color='red'>"+getName()+"</font></strong></html>";}public Icon getIcon() {return icon;}public void setIcon(Icon icon) {this.icon = icon;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

步骤三：节点的封装，是继承DefaultMutableTreeNode

import javax.swing.Icon;public class IconTreeNode extends DefaultMutableTreeNode {private static final long serialVersionUID = -8044774991176225332L;protected Icon icon;protected User user;public IconTreeNode(User user) {//包装对象为User实例的结点的构造方法this(user, true);}public IconTreeNode(User user, boolean allowsChildren) {//allowsChildren也就是准不准许有孩子节点super(user, allowsChildren);this.user = user;this.icon = user.getIcon();}public void setIcon(Icon icon) {this.icon = icon;}public Icon getIcon() {return icon;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}}

步骤四：测试类的实现

import java.awt.BorderLayout;public class IconTreeTest extends JFrame{private static final long serialVersionUID = 6808299663145549457L;private JTree tree;private JPanel pnlMain = new JPanel();private JButton btnAdd = new JButton("添加叶子");private DefaultTreeModel treeModel=null;private DefaultMutableTreeNode nodeRoot = new DefaultMutableTreeNode("all");public IconTreeTest(){‍ init();}//end of constructorpublic void init() {pnlMain.setLayout(new BorderLayout());//先创建User实例User user1 = new User("Andy",ImageManager.getIcon("girl01.png"));User user2 = new User("花花",ImageManager.getIcon("stoneman.png"));//将User实例封装成TreeNodeIconTreeNode node1 = new IconTreeNode(user1);IconTreeNode node2 = new IconTreeNode(user2);nodeRoot.add(node1);nodeRoot.add(node2);//下面构造JTreetree = new JTree(nodeRoot);//设置根Root不可见tree.setRootVisible(false);//设置渲染器DefaultTreeCellRenderer ceeRender = new IconNodeRendereer();tree.setCellRenderer(ceeRender);//下面这一行获取JTree的模型，为了在JButton中实现动态添加而预设的，也可以在JButton的事件响应中再写treeModel=(DefaultTreeModel)tree.getModel();pnlMain.add(tree);pnlMain.add(btnAdd,BorderLayout.SOUTH);setContentPane(pnlMain);setSize(400,500);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//添加事件监听实现动态添加节点btnAdd.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e) {User newUser;            //ImageManager这个类请看User中的说明，这个是自己实现的，只要能获取到Icon就可以了newUser = new User("Andy",ImageManager.getIcon("greenman.png"));IconTreeNode newNode = new IconTreeNode(newUser);treeModel.insertNodeInto(newNode,nodeRoot,nodeRoot.getChildCount()); }});}//end of init()public static void main(String[] args){IconTreeTest test = new IconTreeTest();test.setLocationRelativeTo(null);test.setVisible(true);}}

=====================================================================上面分了4个类文件，渲染器自己就写得很简单，是因为想要的功能就这么多--------显示图片，上面的功能就算完成了，给大家参考。