Aug 28

Draws a filled ellipse 

import javax.swing.*;   // For JPanel, etc.
import java.awt.*;      // For Graphics, etc.
import java.awt.geom.*; // For Ellipse2D, etc.

/** An example of drawing/filling shapes with Java 2D in
 *  Java 1.2 and later.
 *
**************************
public class ShapeExample extends JPanel {
  private Ellipse2D.Double circle =
    new Ellipse2D.Double(10, 10, 350, 350);
  private Rectangle2D.Double square =
    new Rectangle2D.Double(10, 10, 350, 350);

  public void paintComponent(Graphics g) {
    clear(g);
    Graphics2D g2d = (Graphics2D)g;
    g2d.fill(circle);
    g2d.draw(square);
  }

  // super.paintComponent clears off screen pixmap,
  // since we're using double buffering by default.
  protected void clear(Graphics g) {
    super.paintComponent(g);
  }

  protected Ellipse2D.Double getCircle() {
    return(circle);
  }

public static void main(String[] args) {
    WindowUtilities.openInJFrame(new ShapeExample(), 380, 400);
  }
}

Aug 28

JavaTextField.java 

import java.applet.Applet;
import java.awt.*;

/** Lets the user enter the name of any
 *  good programming language. Or does it?
 *  


 *********************

public class JavaTextField extends Applet {
  public void init() {
    setFont(new Font("Serif", Font.BOLD, 14));
    setLayout(new GridLayout(2, 1));
    add(new Label("Enter a Good Programming Language",
                  Label.CENTER));
    LanguageField langField = new LanguageField();
    Font langFont = new Font("SansSerif", Font.BOLD, 18);
    langField.setFont(langFont);
    add(langField);
  }
}

Aug 28

Applet that uses processXxx methods to print detailed reports on mouse events. Illustrates low-level alternative to handling events with listeners. 

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*; 

/** Prints non-detailed reports of mouse events.
 *  Uses the low-level processXxxEvent methods instead
 *  of the usual event listeners.
 *  


 *****************

public class MouseReporter extends Applet {
  public void init() {
    setBackground(Color.blue); // So you can see applet in page
    enableEvents(AWTEvent.MOUSE_EVENT_MASK |
                 AWTEvent.MOUSE_MOTION_EVENT_MASK);
  }

  public void processMouseEvent(MouseEvent event) {
    System.out.println("Mouse enter/exit or click at (" +
                       event.getX() + "," +
                       event.getY() + ").");
    // In case there are MouseListeners attached:
    super.processMouseEvent(event); 
  }

  
  public void processMouseMotionEvent(MouseEvent event) {
    System.out.println("Mouse move/drag at (" +
                       event.getX() + "," +
                       event.getY() + ").");
    // In case there are MouseMotionListeners attached:
    super.processMouseMotionEvent(event);
  }
}

Aug 28

HeadingExample.jsp Page that uses the HeadingTag custom tag 

HeadingExample.jsp Page that uses the HeadingTag custom tag


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- 
Illustration of HeadingTag tag. 

Taken from Core Web Programming Java 2 Edition
from Prentice Hall and Sun Microsystems Press,
.
May be freely used or adapted. 
-->
<HTML>
<HEAD>
<TITLE>Some Tag-Generated Headings</TITLE>
</HEAD>
<BODY>
<%@ taglib uri="cwp-taglib.tld" prefix="cwp" %>
<cwp:heading bgColor="#C0C0C0">
Default Heading
</cwp:heading>
<P>
<cwp:heading bgColor="BLACK" color="WHITE">
White on Black Heading
</cwp:heading>
<P>
<cwp:heading bgColor="#EF8429" fontSize="60" border="5">
Large Bordered Heading
</cwp:heading>
<P>
<cwp:heading bgColor="CYAN" width="100%">
Heading with Full-Width Background
</cwp:heading>
<P>
<cwp:heading bgColor="CYAN" fontSize="60"
                fontList="Brush Script MT, Times, serif">
Heading with Non-Standard Font
</cwp:heading>
</BODY>
</HTML>

package cwp.tags;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.*;

/** Generates an HTML heading with the specified background
 *  color, foreground color, alignment, font, and font size.
 *  You can also turn on a border around it, which normally
 *  just barely encloses the heading, but which can also
 *  stretch wider. All attributes except the background
 *  color are optional.
 *  <P>
 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class HeadingTag extends TagSupport {
  private String bgColor; // The one required attribute
  private String color = null;
  private String align="CENTER";
  private String fontSize="36";
  private String fontList="Arial, Helvetica, sans-serif";
  private String border="0";
  private String width=null;

  public void setBgColor(String bgColor) {
    this.bgColor = bgColor;
  }

  public void setColor(String color) {
    this.color = color;
  }

  public void setAlign(String align) {
    this.align = align;
  }

  public void setFontSize(String fontSize) {
    this.fontSize = fontSize;
  }

  public void setFontList(String fontList) {
    this.fontList = fontList;
  }

  public void setBorder(String border) {
    this.border = border;
  }

  public void setWidth(String width) {
    this.width = width;
  }

  public int doStartTag() {
    try {
      JspWriter out = pageContext.getOut();
      out.print("<TABLE BORDER=" + border +
                " BGCOLOR=\"" + bgColor + "\"" +
                " ALIGN=\"" + align + "\"");
      if (width != null) {
        out.print(" WIDTH=\"" + width + "\"");
      }
      out.print("><TR><TH>");
      out.print("<SPAN STYLE=\"" +
                "font-size: " + fontSize + "px; " +
                "font-family: " + fontList + "; ");
      if (color != null) {
        out.println("color: " + color + ";");
      }
      out.print("\"> "); // End of <SPAN ...>
    } catch(IOException ioe) {
      System.out.println("Error in HeadingTag: " + ioe);
    }
    return(EVAL_BODY_INCLUDE); // Include tag body
  }

  public int doEndTag() {
    try {
      JspWriter out = pageContext.getOut();
      out.print("</SPAN></TABLE>");
    } catch(IOException ioe) {
      System.out.println("Error in HeadingTag: " + ioe);
    }
    return(EVAL_PAGE); // Continue with rest of JSP page
  }
}

Aug 28

PrimeExample.jsp Page that uses the PrimeTag custom tag 

PrimeExample.jsp Page that uses the PrimeTag custom tag


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- 
Illustration of PrimeTag tag. 

Taken from Core Web Programming Java 2 Edition
from Prentice Hall and Sun Microsystems Press,
.
May be freely used or adapted. 
-->
<HTML>
<HEAD>
<TITLE>Some N-Digit Primes</TITLE>
<LINK REL=STYLESHEET
      HREF="JSP-Styles.css"
      TYPE="text/css">
</HEAD>
<BODY>
<H1>Some N-Digit Primes</H1>
<%@ taglib uri="cwp-taglib.tld" prefix="cwp" %>
<UL>
  <LI>20-digit: <cwp:prime length="20" />
  <LI>40-digit: <cwp:prime length="40" />
  <LI>80-digit: <cwp:prime length="80" />
  <LI>Default (50-digit): <cwp:prime />
</UL>
</BODY>
</HTML>



package cwp.tags;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.*;

/** Generates an N-digit random prime (default N = 50).
 *  Extends SimplePrimeTag, adding a length attribute
 *  to set the size of the prime. The doStartTag
 *  method of the parent class uses the len field
 *  to determine the approximate length of the prime.
 *  <P>
 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class PrimeTag extends SimplePrimeTag {
  public void setLength(String length) {
    try {
      len = Integer.parseInt(length);
    } catch(NumberFormatException nfe) {
      len = 50;
    }
  }
}

Aug 28

SimplePrimeExample.jsp Page that uses the SimplePrimeTag custom tag 

SimplePrimeExample.jsp Page that uses the SimplePrimeTag custom tag

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- 
Illustration of SimplePrimeTag tag. 

Taken from Core Web Programming Java 2 Edition
from Prentice Hall and Sun Microsystems Press,
.
May be freely used or adapted. 
-->
<HTML>
<HEAD>
<TITLE>Some 50-Digit Primes</TITLE>
<LINK REL=STYLESHEET
      HREF="JSP-Styles.css"
      TYPE="text/css">
</HEAD>
<BODY>
<H1>Some 50-Digit Primes</H1>
<%@ taglib uri="cwp-taglib.tld" prefix="cwp" %>
<UL>
  <LI><cwp:simplePrime />
  <LI><cwp:simplePrime />
  <LI><cwp:simplePrime />
  <LI><cwp:simplePrime />
</UL>
</BODY>
</HTML>

Aug 28

SimpleExample.jsp Page that uses the ExampleTag custom tag. 

SimpleExample.jsp Page that uses the ExampleTag custom tag.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- 
Illustration of very simple JSP custom tag. 

Taken from Core Web Programming Java 2 Edition
from Prentice Hall and Sun Microsystems Press,
.
May be freely used or adapted. 
-->
<HTML>
<HEAD>
<%@ taglib uri="cwp-taglib.tld" prefix="cwp" %>
<TITLE><cwp:example /></TITLE>
<LINK REL=STYLESHEET
      HREF="JSP-Styles.css"
      TYPE="text/css">
</HEAD>
<BODY>
<H1><cwp:example /></H1>
<cwp:example />
</BODY>
</HTML>


ExampleTag

package cwp.tags;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.*;

/** Very simple JSP tag that just inserts a string
 *  ("Custom tag example...") into the output.
 *  The actual name of the tag is not defined here;
 *  that is given by the Tag Library Descriptor (TLD)
 *  file that is referenced by the taglib directive
 *  in the JSP file.
 *  <P>
 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class ExampleTag extends TagSupport {
  public int doStartTag() {
    try {
      JspWriter out = pageContext.getOut();
      out.print("Custom tag example " +
                "(cwp.tags.ExampleTag)");
    } catch(IOException ioe) {
      System.out.println("Error in ExampleTag: " + ioe);
    }
    return(SKIP_BODY);
  }
}

Aug 28

ExampleTag.java Very simple custom tag. Remember to install it in the WEB-INF/classes/cwp/tags directory. 

ExampleTag.java Very simple custom tag. Remember to install it in the WEB-INF/classes/cwp/tags directory. 


package cwp.tags;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.*;

/** Very simple JSP tag that just inserts a string
 *  ("Custom tag example...") into the output.
 *  The actual name of the tag is not defined here;
 *  that is given by the Tag Library Descriptor (TLD)
 *  file that is referenced by the taglib directive
 *  in the JSP file.
 *  <P>
 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class ExampleTag extends TagSupport {
  public int doStartTag() {
    try {
      JspWriter out = pageContext.getOut();
      out.print("Custom tag example " +
                "(cwp.tags.ExampleTag)");
    } catch(IOException ioe) {
      System.out.println("Error in ExampleTag: " + ioe);
    }
    return(SKIP_BODY);
  }
}

Aug 28

AccessCountBean.java Bean used to illustrate the difference between running jsp:setProperty for every request vs. only when the object is created 

AccessCountBean.java Bean used to illustrate the difference between running jsp:setProperty for every request vs. only when the object is created

package cwp;

/** Simple bean to illustrate sharing beans through
 *  use of the scope attribute of jsp:useBean.
 *  <P>
 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class AccessCountBean {
  private String firstPage;
  private int accessCount = 1;

  public String getFirstPage() {
    return(firstPage);
  }

  public void setFirstPage(String firstPage) {
    this.firstPage = firstPage;
  }

  public int getAccessCount() {
    return(accessCount++);
  }
}

Aug 28

SaleEntry2.jsp Page that uses the SaleEntry bean, using the param attribute to read request parameters and assign them to bean properties

SaleEntry2.jsp Page that uses the SaleEntry bean, using the param attribute to read request parameters and assign them to bean properties

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- 
Example of using jsp:setProperty and an explicity association
with an input parameter. See SaleEntry1.jsp
and SaleEntry3.jsp for alternatives. 
   
Taken from Core Web Programming Java 2 Edition
from Prentice Hall and Sun Microsystems Press,
.
May be freely used or adapted.
-->
<HTML>
<HEAD>
<TITLE>Using jsp:setProperty</TITLE>
<LINK REL=STYLESHEET
      HREF="JSP-Styles.css"
      TYPE="text/css">
</HEAD>

<BODY>
<TABLE BORDER=5 ALIGN="CENTER">
  <TR><TH CLASS="TITLE">
      Using jsp:setProperty</TABLE>
<jsp:useBean id="entry" class="cwp.SaleEntry" />
<jsp:setProperty 
    name="entry"
    property="itemID"
    param="itemID" />
<jsp:setProperty 
    name="entry"
    property="numItems"
    param="numItems" />
<%-- WARNING! Both the JSWDK 1.0.1 and the Java Web Server
              have a bug that makes them fail on double
              type conversions of the following sort.
--%>
<jsp:setProperty 
    name="entry"
    property="discountCode"
    param="discountCode" />
<BR>
<TABLE ALIGN="CENTER" BORDER=1>
<TR CLASS="COLORED">
  <TH>Item ID<TH>Unit Price<TH>Number Ordered<TH>Total Price
<TR ALIGN="RIGHT">
  <TD><jsp:getProperty name="entry" property="itemID" />
  <TD>$<jsp:getProperty name="entry" property="itemCost" />
  <TD><jsp:getProperty name="entry" property="numItems" />
  <TD>$<jsp:getProperty name="entry" property="totalCost" />
</TABLE>     
</BODY>
</HTML>


SaleEntry.java //SaleEntry Bean

package cwp;

/** Simple bean to illustrate the various forms
 *  of jsp:setProperty.
 *  <P>
 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class SaleEntry {
  private String itemID = "unknown";
  private double discountCode = 1.0;
  private int numItems = 0;

  public String getItemID() {
    return(itemID);
  }

  public void setItemID(String itemID) {
    if (itemID != null) {
      this.itemID = itemID;
    } else {
      this.itemID = "unknown";
    }
  }

  public double getDiscountCode() {
    return(discountCode);
  }

  public void setDiscountCode(double discountCode) {
    this.discountCode = discountCode;
  }

  public int getNumItems() {
    return(numItems);
  }

  public void setNumItems(int numItems) {
    this.numItems = numItems;
  }

  // In real life, replace this with database lookup.

  public double getItemCost() {
    double cost;
    if (itemID.equals("a1234")) {
      cost = 12.99*getDiscountCode();
    } else {
      cost = -9999;
    }
    return(roundToPennies(cost));
  }

  private double roundToPennies(double cost) {
    return(Math.floor(cost*100)/100.0);
  }

  public double getTotalCost() {
    return(getItemCost() * getNumItems());
  }
}