helpdisplay.java

一个用Java实现的小型

import java.net.*;

public class HelpDisplay extends javax.swing.JFrame {
  private final static String fileSeperator = System.getProperty("file.separator");
  private final static String workingDir = System.getProperty("user.dir");
  private static URL introPage;
  private static URL pathPage;
  private URLHistory history;
  
  /** Creates new form HelpDisplay */
  public HelpDisplay() {
    initComponents();
    history = new URLHistory(10);
    try {
      introPage = new URL("file:"+workingDir+fileSeperator+"docs"+fileSeperator+"index.html");
      pathPage = new URL("file:"+workingDir+fileSeperator+"docs"+fileSeperator+"$APPPATHS");
      mainEditorPane.setPage(introPage);
      history.add(introPage);
    } catch (Exception e) {
      System.err.println("Cannot find help page "+e);
    }
  }
  
  /** This method is called from within the constructor to
   * initialize the form.
   * WARNING: Do NOT modify this code. The content of this method is
   * always regenerated by the Form Editor.
   */
  private void initComponents() {//GEN-BEGIN:initComponents
    helpScrollPane = new javax.swing.JScrollPane();
    mainEditorPane = new javax.swing.JEditorPane();
    buttonPanel = new javax.swing.JPanel();
    backButton = new javax.swing.JButton();
    forwardButton = new javax.swing.JButton();
    closeButton = new javax.swing.JButton();
    
    addWindowListener(new java.awt.event.WindowAdapter() {
      public void windowClosing(java.awt.event.WindowEvent evt) {
        exitForm(evt);
      }
    });
    
    helpScrollPane.setPreferredSize(new java.awt.Dimension(600, 300));
    mainEditorPane.setEditable(false);
    mainEditorPane.addHyperlinkListener(new javax.swing.event.HyperlinkListener() {
      public void hyperlinkUpdate(javax.swing.event.HyperlinkEvent evt) {
        gotoURL(evt);
      }
    });
    
    helpScrollPane.setViewportView(mainEditorPane);
    
    getContentPane().add(helpScrollPane, java.awt.BorderLayout.CENTER);
    
    buttonPanel.setLayout(new java.awt.FlowLayout(java.awt.FlowLayout.RIGHT));
    
    backButton.setText("<<");
    backButton.setEnabled(false);
    backButton.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
        goBack(evt);
      }
    });
    
    buttonPanel.add(backButton);
    
    forwardButton.setText(">>");
    forwardButton.setEnabled(false);
    forwardButton.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
        goForward(evt);
      }
    });
    
    buttonPanel.add(forwardButton);
    
    closeButton.setText("Close");
    getRootPane().setDefaultButton(closeButton);
    closeButton.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
        close(evt);
      }
    });
    
    buttonPanel.add(closeButton);
    
    getContentPane().add(buttonPanel, java.awt.BorderLayout.SOUTH);
    
    pack();
  }//GEN-END:initComponents

  private void goForward(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_goForward
    try {
      setPage(history.getNext());
    } catch (Exception e) {
      System.err.println("Couldn't get next page!");
    }
  }//GEN-LAST:event_goForward

  private void goBack(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_goBack
    try {
      setPage(history.getPrevious());
    } catch (Exception e) {
      System.err.println("Couldn't get previous page!");
    }
  }//GEN-LAST:event_goBack

  private void gotoURL(javax.swing.event.HyperlinkEvent evt) {//GEN-FIRST:event_gotoURL
    if(evt.getEventType().equals(javax.swing.event.HyperlinkEvent.EventType.ACTIVATED)) {
      try {
        URL newPage = evt.getURL();
        setPage(newPage);
        history.add(newPage);
      } catch (Exception e) {
        System.err.println("Bad page: "+e);
      }
    }
  }//GEN-LAST:event_gotoURL

  private void close(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_close
    exitForm();
  }//GEN-LAST:event_close
    
    private void exitForm(java.awt.event.WindowEvent evt) {//GEN-FIRST:event_exitForm
      exitForm();
    }//GEN-LAST:event_exitForm
    
    private void setPage(URL page) throws java.io.IOException {
      if(page.equals(pathPage)) {
        mainEditorPane.setDocument(mainEditorPane.getEditorKit().createDefaultDocument());
        mainEditorPane.setContentType("text/html");
        mainEditorPane.setText(getPathPage());
      } else {
        mainEditorPane.setPage(page);
      }
    }
    
    /** Exit the Application */
    private void exitForm() {
      setVisible(false);
    }
    
    private String getPathPage() {
      return "<HTML>\n<BODY>\n<FONT Size=\"+1\">File Paths You Might Need to Know</FONT>\n<P>\n"+
      "<DL>\n<DT><B>What is my extensions directory?</B>\n"+
      "<DD>It is <CODE>"+System.getProperty("java.ext.dirs")+"</CODE>.\n<P>\n"+
      "<DT><B>Where are my preferences stored?</B>\n"+
      "<DD>Preferences are stored in files ending in .def within your "+
      "user directory, which is <CODE>"+CsltComm.prefsDir+"</CODE>.\n<P>\n"+
      "<DT><B>What directory is ConsultComm running from?</B>\n"+
      "<DD>The working directory for this applicaition is <CODE>"+System.getProperty("user.dir")+"</CODE>.\n<P>\n"+
      "</DL>\n</BODY>\n</HTML>";
    }
    
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JScrollPane helpScrollPane;
    private javax.swing.JEditorPane mainEditorPane;
    private javax.swing.JPanel buttonPanel;
    private javax.swing.JButton backButton;
    private javax.swing.JButton forwardButton;
    private javax.swing.JButton closeButton;
    // End of variables declaration//GEN-END:variables
    
    private class URLHistory {
      private URL[] historyList;
      private int currIndex;
      private int startIndex;
      private int endIndex;

      URLHistory() {
        historyList = new URL[20];
        startIndex = 0;
        endIndex = 0;
        currIndex = -1;
      }
      URLHistory(int size) {
        historyList = new URL[size];
        startIndex = 0;
        endIndex = 0;
        currIndex = -1;
      }
      
      protected URL getPrevious() {
        if(--currIndex < 0) currIndex = historyList.length-1;
        URL page = historyList[currIndex];
        forwardButton.setEnabled(true);
        if(! existsPrevious()) backButton.setEnabled(false);
        return page;
      }
      protected URL getNext() {
        currIndex = (currIndex+1)%historyList.length;
        URL page = historyList[currIndex];
        backButton.setEnabled(true);
        if(! existsNext()) forwardButton.setEnabled(false);
        return page;
      }
      protected boolean existsPrevious() {
        return currIndex != startIndex;
      }
      protected boolean existsNext() {
        return currIndex != endIndex-1;
      }
      protected void add(URL page) {
        currIndex = (currIndex+1)%historyList.length;
        historyList[currIndex] = page;
        endIndex = (currIndex+1)%historyList.length;
        if(endIndex == startIndex)
          startIndex = (startIndex+1)%historyList.length;
        forwardButton.setEnabled(false);
        if(existsPrevious()) backButton.setEnabled(true);
      }
    }
}