[JAVA100 example]076, using swing in applets

Import java.awt.*;


import java.awt.event.*;


import javax.swing.*;


import javax.swing.event.*;


import javax.swing.tree.*;


import java.io.*;


import java.net.*;


import java.util.*;


import java.applet.*;


/**


* <p>title:applet using swing</p>


* <p>description: Use Swing's japplet to implement tree functions. </p>


* <p>copyright:copyright (c) 2003</p>


* <p>Filename:PageTree.java</p>


* @version 1.0


*/


public class Pagetree extends JApplet implements Treeselectionlistener {


defaultmutabletreenode[] nodeat = new defaultmutabletreenode[256];


String target = null;


Hashtable links = new Hashtable ();


Appletcontext context;


public void init () {


//Get the contents of the applet


context = getAppletContext ();


//define root node


Defaultmutabletreenode root = null;


Getcontentpane (). setlayout (New BorderLayout ());


//Get parameters. The data configuration file that is defined.


String s = getparameter ("file");


if (s!= null) {


try {


//Use URL to open the data file for use on the network.


url url = new URL (getdocumentbase (), s);


bufferedreader br = new BufferedReader (


New InputStreamReader (Url.openstream (), "Jisautodetect"));


//Read the first row of data, if empty then do not perform


String line = Br.readline ();


if (line = = null) return;


root = new Defaultmutabletreenode (line);


nodeat[0] = root;


int level = 0;


while (line = Br.readline ())!= null) {


//Use "|" Separate data


StringTokenizer st = new StringTokenizer (line, "|");


String token = St.nexttoken ();


int n = countspaces (token);


//Add node name


defaultmutabletreenode node = new Defaultmutabletreenode (Token.trim ());


//COMPUTE Node Series


for (int i = level + 1; i < n; i++) {


Defaultmutabletreenode dummy = new Defaultmutabletreenode ("");


Nodeat[i].add (dummy);


nodeat[i+1] = dummy;


　　 }


level = n;


nodeat[n].add (node);


nodeat[n+1] = node;


//To "|" The data after the symbol is processed


if (St.hasmoretokens ()) {


token = St.nexttoken ();


try {


url = new URL (Token.trim ());


links.put (node, URL);


} catch (Malformedurlexception ex) {


Ex.printstacktrace ();


　　　}


　　 }


　　}


} catch (Malformedurlexception e) {


E.printstacktrace ();


} catch (IOException e) {


E.printstacktrace ();


　 }


s = getparameter ("target");


if (s!= null) target = S.trim ();


JTree tree = new JTree (root);


///Add Tree Selection Monitor


Tree.addtreeselectionlistener (this);


JScrollPane jsp = new JScrollPane (tree);


Getcontentpane (). Add (JSP, Borderlayout.center);


　}


}


/**


*<br> Method Description: Calculate the number of spaces


*<br> input Parameters:


*<br> return type:


*/


private int countspaces (String s) {


int n = 0;


while (S.charat (n) ==´´) {


n++;


　}


return n;


}


/**


*<br> Method Description: Tree selection monitoring Implementation method


*<br> input parameter: treeselectionevent e Select tree Node event


*<br> return type:


*/


public void valuechanged (Treeselectionevent e) {


TreePath Path = E.getpath ();


Object o = path.getlastpathcomponent ();


url = (URL) links.get (o);


if (URL!= null) {


System.out.println (Links.get (o));


//Open the connection to notify the browser to load the Web page (using the browser to open the applet)


context.showdocument (URL);


　}


}


}