| 用java小程序applet实现无限级树结构 | |
|
1．该树的特点： 1）无限级树结构 理论上树的深度可以无限，树的深度由xml文件所给的信息确定； 数据加载采用一次加载和动态加载相结合的方法； 每次打开相关页时重新加载树结构，真正的做到了建立树的动态性。 2）复用性 由于这棵树是通过读取xml文件建立的，树的程序代码固定，所以具有很强的复用性。只需要给出xml文件，程序就可以建立对应的树。 3）与用户的交互 由于该程序是用java小程序实现的，所以可以利用java语言中监听事件的类，以响应用户操作。与用户具有更好的交互性。 2．程序结构 这棵树主要有三个类实现： 1） 类TreeNode：该类起辅助作用，用来描述树的数据结构，并提供一些setter，getter函数用来设置树结构的属性。 2） 类IconRender：该类也是一个辅助类，用来设置树节点的图标。并且可以根据树节点的选中状态改变图标。 3） 类AppletTree：该类是建立这棵树的主要类，它继承自Applet并且实现了TreeSelectionListener接口，以用来监听用户操作。树结构由java类JTree显示，我们只需要合理的设定JTree的属性就可以构造出这棵树。而它的属性是通过jdom中的Element读取xml文件提供的。上面已经提到监听用户操作是通过实现TreeSelectionListener接口完成的，但是只监听不响应毫无用处。怎样才能将监听到的用户操作传给相应的类以响应用户的操作呢？这里用的方法是通过URL将参数传递给jsp文件，再由jsp文件传给相应的操作类实现的。 这三个类的代码如下： 1．TreeNode类 public class TreeNode{ private String id; private String name; private String link; public TreeNode(String id,String name,String link){ this.id=id; this.name=name; this.link=link; } public String getId(){ return id; } public void setId(String Id){ this.id=Id; } public void setName(String Name){ this.name=Name; } public String getName(){ return name; } public String toString(){ return name; } public String getLink(){ return link; } public void setLink(String link){ this.link=link; } } 2. IconRender类 import javax.swing.*; import java.awt.*; import javax.swing.tree.*; import javax.swing.tree.DefaultTreeCellRenderer; IconRender class extends DefaultTreeCellRenderer { //创建用于显示的图标 public static final ImageIcon leafSelectedIcon = new ImageIcon("OpenedFolder.ico"); public static final ImageIcon leafUnSelectedIcon = new ImageIcon("closedFolder.ico"); public static final ImageIcon folderOpen = new ImageIcon("OpenedFolder.ico"); public static final ImageIcon folderClose = new ImageIcon("closedFolder.ico"); //设定图标随选中状态的变化 public Component getTreeCellRendererComponent(JTree tree,Object value,boolean selected，boolean expanded, boolean leaf, int row,boolean hasFocus) { super.getTreeCellRendererComponent(tree,value, selected, expanded, leaf, row, hasFocus); if (leaf && selected) { setIcon(IconRender.leafSelectedIcon); } else if (leaf) { setIcon(IconRender.leafUnSelectedIcon); } return this; } public IconRender() { super(); if((leafSelectedIcon != null)&&(leafUnSelectedIcon != null)) System.out.println("IconRender:trace"); setLeafIcon(leafUnSelectedIcon); setOpenIcon(folderOpen); setClosedIcon(folderClose); } } 3．AppletTree类 import javax.swing.event.*; import java.awt.*; import java.applet.*; import javax.swing.*; import javax.swing.tree.*; import java.awt.event.*; import org.jdom.*; //import org.w3c.dom.NodeList; import org.jdom.input.*; import java.io.*; import java.util.*; import java.net.*; import java.awt.*; import javax.swing.*; import javax.swing.border.*; import javax.swing.plaf.*; import javax.swing.plaf.basic.*; import javax.swing.plaf.metal.*; import java.io.*; //import netscape.javascript.*; class MyWindowListener extends WindowAdapter { public void windowClosing(WindowEvent e) { System.exit(1); } } public class AppletTree extends Applet implements TreeSelectionListener { private JTree tree; private TreePath path; private JScrollPane treeView; private DefaultMutableTreeNode top; private DefaultMutableTreeNode clicknode; private String link; public AppletTree(){ } MouseListener ml = new MouseAdapter() { public void mousePressed(MouseEvent e) { int selRow = tree.getRowForLocation(e.getX(), e.getY()); TreePath selPath = tree.getPathForLocation(e.getX(), e.getY()); if(selRow != -1) { if(e.getClickCount() == 1) { System.out.print("点击一次鼠标"); //得到最后一个节点 DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode)selPath.getLastPathComponent(); boolean isLeaf = treeNode.isLeaf(); TreeNode objTreeNode = (TreeNode)treeNode.getUserObject(); System.out.println(isLeaf); System.out.println(objTreeNode .getName()) ; System.out.println(objTreeNode .getId()) ; if(isLeaf) {//如果为叶子节点就传出去进行查询操作 try { getAppletContext().showDocument(new URL("http://127.0.0.1:8080/tree/showDevice.htm"),"f2" ); } catch(Exception ex) { System.out.print(ex); } } } else if(e.getClickCount() == 2) { System.out.print("点击两次鼠标"); //getAppletContext().showDocument(new URL("http://www.csdn.net/")); //myDoubleClick(selRow, selPath); } } } }; public void start() { super.start(); } public void init(){ try{ super.init(); this.setLayout(new GridLayout(1,1)); tree=createTree(new FileInputStream("e:/example/TreeXML.xml")); tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION); tree.putClientProperty("JTree.lineStyle","Angled"); tree.setShowsRootHandles(true); tree.setEditable(true); tree.addTreeSelectionListener( this ); IconRender render=new IconRender(); tree.setCellRenderer(render); treeView = new JScrollPane(tree); //topPanel.add(tree); this.add(treeView); tree.addMouseListener(ml); }catch(Exception e){ e.printStackTrace(); } } public JTree createTree(InputStream is){ SAXBuilder builder = new SAXBuilder(); try { Document doc = builder.build(is); Element root=doc.getRootElement(); TreeNode rootNode=new TreeNode(root.getAttributeValue("id"),root.getAttributeValue("name"),root.getAttributeValue("HaveChildren")); top=new DefaultMutableTreeNode(rootNode); addNode(root,top); } catch (Exception ex) { ex.printStackTrace(); } //可以在这里改变jtree中连线的颜色 UIManager.put( "Tree.hash", new ColorUIResource(Color.red) ); return new JTree(top); } /** * * @param e 待加入树中的jdom元素 * @param fatherNode 树节点父亲节点 */ private void addNode(Element e,DefaultMutableTreeNode fatherNode){ try{ Iterator it=e.getChildren().iterator(); if(!it.hasNext()) return; while(it.hasNext()){ Element sub=(Element)it.next(); String id=new String(sub.getAttributeValue("id").getBytes(),"GB2312"); String name=new String(sub.getAttributeValue("name").getBytes(),"GB2312"); String link=new String(sub.getAttributeValue("HaveChildren").getBytes(),"GB2312"); System.out.println(id); System.out.println(name); System.out.println(link); TreeNode tempNode=new TreeNode(id,name,link); DefaultMutableTreeNode node=new DefaultMutableTreeNode(tempNode); fatherNode.add(node); if(link.equals("true")){ System.out.println("true~! equal test"); addNode(sub,node); } } } catch(Exception exp) { System.out.println("encoding fail"); } } /** * 根据id,查找树节点,//广度优先 * @param id 节点id * @param rootNode 树根节点 * @return DefaultMutableTreeNode */ private DefaultMutableTreeNode getTreeNode(String id,DefaultMutableTreeNode rootNode){ DefaultMutableTreeNode returnNode=null; if(rootNode!=null){ Enumeration enum=rootNode.breadthFirstEnumeration(); while(enum.hasMoreElements()){ DefaultMutableTreeNode temp=(DefaultMutableTreeNode)enum.nextElement(); TreeNode node=(TreeNode)temp.getUserObject(); if(node.getId().equals(id)){ returnNode=temp; break; } } } return returnNode; } public void valueChanged( TreeSelectionEvent event ){ if( event.getSource() == tree ){ path = event.getPath(); clicknode=(DefaultMutableTreeNode)path.getLastPathComponent(); Object uo=clicknode.getUserObject(); if(uo instanceof TreeNode){ TreeNode nd=(TreeNode)clicknode.getUserObject(); link=nd.getLink(); } } } public static void main(String[] args ){ JFrame frame1=new JFrame("test"); AppletTree tree=new AppletTree(); tree.init(); frame1.getContentPane().add(tree); frame1.setSize(600,600); frame1.show(); frame1.addWindowListener(new MyWindowListener()); } } |
全站熱搜
留言列表
