Manning: Java Applets and Channels Without Programming

Java Applets and Channels Without Programming Ronny Richardson, Michael Shoffner, Marq Singer, Bruce Murray, and Jack Gambol 1997 \| 372 pages ISBN: 1884777392
Out of print	$37.95	Softbound print book

RESOURCES

DESCRIPTION

If you want to use Java to enhance your Web site, you have two choices: you can write the Java applet yourself or you can find an already written Java applet that meets your needs. If you prefer not to do the writing yourself, then Java Applets and Channels Without Programming is for you. It collects almost 100 applets on a CD with detailed instructions on how to use each applet. In addition, style issues are discussed in detail; not only will you learn how to use each applet, you will learn when and where it is appropriate to use each applet. The book also introduces the new concept of channels and shows how these can be used on your web site as well.

The CD-ROM also contains an exclusive applet configuration utility, a program that allows you to configure the Java applets on the CD-ROM in a WYSIWYG (What You See Is What You Get) environment. When using the utility to configure Java applets, you do not need to know any Java programming or even any HTML programming. All you do is change the value of a parameter and click on a button to see the resulting change to the applet. The applet configuration utility is written in Java and runs in your browser, so it runs on any computer platform for which there is a Java-enabled browser.

The CD-ROM also provides example web pages for more than 60 of the included applets, so you can learn how to use the applets in real-world situations.

What's inside:

Easy introduction to Java
How Java applets work with your HTML code
Step-by-step instructions for using the applets on the CD-ROM
Step-by-step instructions for using dozens of other applets freely available on the Web

The CD-ROM contains:

Nearly a hundred ready-to-run Java applets, each with sample code
The applet configuration utility
Fully-realized example web pages for more than 60 applets

If you are not a programmer, if you don't have time to learn programming, why struggle to write applets on your own? Enhance your web site quickly and easily with Java Applets and Channels Without Programming.

ABOUT THE AUTHORS...

Ronny Richardson is the author of twenty computer software books. Michael Shoffner is a software developer and co-author of Java Network Programming published by Manning Publications. Marq Singer is a computer science instructor and a Java developer and educator at Prominence Dot Com. Bruce Murray teaches at the University of Alabama and is an experience webmaster. Jack Gambol is a writer and designer of several successful entertainment-related sites.

Sample Chapters

This chapter covers those applets that did not "fit" in any of the other chapters. You will find many strange, interesting, and useful applets in this chapter.

10.1.1 Amortization applet

The Amortization applet gives you the ability to include a very useful financial calculator on your Web site. The applet, shown in figure 10.1, allows you to calculate loan payments and amortization right on your Web site. The user simply enters the loan amount, the interest rate, the number of payments to make per year, and the number of years the loan is to run. The applet does the rest.

Sample HTML code

Use the following HTML code to include the Amortization applet in your Web page:


<applet code=amort.class width=550 height=400>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, the Amortization applet does not use parameters.

10.1.2 Biorhythm

Once you enter your birth date, the Biorhythm applet quickly computes your biorhythms and displays them on the screen (figure 10.2). To use the Biorhythm applet, enter your birthday in the form year-month-day and then click on the Redraw button. The applet will then draw your three biorhythms with a horizontal bar to represent zero and a vertical bar to represent today's date.

Sample HTML code

Use the following HTML code to include Biorhythm in your Web page:


<applet code="biorhythm.class" width=450 height=300>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, Biorhythm does not use any parameters.

A note on biorhythms

There are actually three separate biorhythmsÑphysical, emotional, and intellectual. The three are supposed to vary on a regular, calendar-based pattern. You are supposed to be stronger when the physical biorhythm is high and weaker when it is low, for example. Some people claim that biorhythms have a scientific basis and can help you plot the times when you will be in peak form. Study after study has discredited this, and I do not believe in or endorse biorhythms. However, the biorhythm is an interesting applet.

10.1.3 Bouncing Line

The Bouncing Line applet displays a series of moving lines against a plain background (figure 10.3). This display is similar to a popular Windows 95 screen saver.

Sample HTML code

Use the following HTML code to include Bouncing Line in your Web page:

<applet code=BouncingLineApp.class width=300 height=300 align=middle>

<param name=num_lines value=3>

</applet>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameter you can use with Bouncing Line is num_lines. This parameter sets the number of different sets of lines that will be moving inside the applet area.

10.1.4 Bubbles

The Bubbles applet displays moving bubbles against a black background (figure 10.4). These moving bubbles can be very calming. This applet would be useful on any site associated with aquariums, fishing, or scuba diving.

Sample HTML code

Use the following HTML code to include Bubbles in your Web page:


<applet code="Bubbles.class" width=400 height=400>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, Bubbles does not use any parameters.

10.1.5 Color Chooser applet

The Color Chooser applet gives you the ability to visualize the color scheme for your Web page very quickly and simply (figure 10.5). Using the drop-down box, you select the component of your Web page for which you wish to change the color. You can change the color for the text, background, links, vlinks, and miscellaneous text. Next, you enter the hexadecimal components for red, green, and blue. Now, you click on the Redisplay button and the applet changes its color scheme to match what you have entered.

The Color Chooser applet is more useful in the design stage than it is to the end user. For this reason, you might want to install it on a maintenance Web page that only you use rather than on one of your production pages. Of course, Web pages devoted to Web design could use it directly.

Sample HTML code

Use the following HTML code to include the Color Chooser applet in your Web page:


<applet code=colors.class width=600 height=150>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, the Color Chooser applet does not use parameters.

10.1.6 Color Wheel

The Color Wheel applet helps you determine the RGB, HSB, and HTML values for a color. First, select the color you wish to use by clicking on the wheel. Next, slide the brightness indicator for the desired brightness. You slide it to the left for less bright or to the right for more bright. The selected color will be used to fill in the background color surrounding the color wheel image. You can then click on the RGB tab to get the RGB and HTML values for that color. You can also click on the HSB tab to get the hue, saturation, or brightness values. All three tabs are shown in figure 10.6.

While Color Wheel is very useful, it is much more useful in Web page development than it is for the users of your Web page. For this reason, you might want to place the applet on a special maintenance page for your own use.

Sample HTML code

Use the following HTML code to include Color Wheel in your Web page:


<applet code=WheelTest.class width=200 height=240>

<param name=size value=64>

</applet>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameter you can use with Color Wheel is size. This specifies the size of the wheel to display. It is measured in pixels, but it specifies one half the diameter. Thus, if you specify a width of 200 for the applet, a size of 100 will cause the wheel to completely fill the applet area, leaving no room to use the background to display the selected color.

10.1.7 The Fish Tank applet

The Fish Tank applet displays an aquarium with moving bubbles and moving fish (figure 10.7). This can have a soothing effect. It would also be useful for any Web site devoted to pets or aquariums.

Sample HTML code

Use the following HTML code to include the Fish Tank applet in your Web page:

<applet code="FishTank.class" width=400 height=150>

<param name=bgcolor value="#0000F0">

</applet>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameter you can use with the Fish Tank applet is:

bgcolor This is the background color, specified in hexadecimal with a leading pound sign.

10.1.8 Lightning Animation

The Lightning Animation applet displays a city skyline at the bottom of a large sky with a lightning storm in progress (figure 10.8). As you watch, the lightning flashes and the sky changes colors with the flashes of lightning. The attention-grabbing display can help draw attention to your Web page.

Sample HTML code

Use the following HTML code to include Lightning Animation in your Web page:

<applet code=Lightning.class width=72 height=72>

</APPLET>

Parameters

Other than the usual height, width, code, and codebase parameters, Lightning Animation does not use parameters.

10.1.9 Linear Ballet

The Linear Ballet applet displays a set of lines that moves around the applet area in a predictable and enjoyable fashion (figure 10.9). Linear Ballet makes a simple yet pretty pattern that can be used for a logo or other decoration. Figure 10.10 shows the Linear Ballet sample Web page from the CD that comes with this book.

Sample HTML code

Use the following HTML code to include Linear Ballet in your Web page:

<applet code="LinearBallet.class" WIDTH=400 HEIGHT=200>

</APPLET>

Parameters

Other than the usual height, width, code, and codebase parameters, Linear Ballet does not use parameters.

10.1.10 Little Wire Doo-Dad

The Little Wire Doo-Dad applet displays a constantly rotating, wire-frame model inside the applet area (figure 10.11). The model rotates around each axis, which is an instance of a class. The applet is single-threaded and double-buffered.

Sample HTML code

Use the following HTML code to include Little Wire Doo-Dad in your Web page:

<applet code="wire" width=100 height=100>

<PARAM name="rgbfgcolor" value="aa0000">

<PARAM name="rgbbgcolor" value="ffffff">

<PARAM name="axis" value="10">

<PARAM name="delay" value="20">

</APPLET>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameters you can use with Little Wire Doo-Dad are as follows:

rgbfgcolor This is the color for the wire figure, in hexadecimal.

rgbbgcolor This is the background color, in hexadecimal.

axis This is the number of axes to include in the figure. The higher the number, the more complex the figure and the more complex its rotations.

delay This is the time, in milliseconds, to delay between movements.

10.1.11 Map applet

The Map applet displays a map on the screen. Figure 10.12 shows a full scale and a zoomed view. You can zoom in or out by clicking on the magnifying glass with the plus to zoom in or the minus to zoom out and then clicking on the map. These are the first two magnifying glasses in figure 10.12.

The third magnifying glass in figure 10.12 lets you center the map. After clicking on this magnifying glass, you click on the part of the map that you wish to be the center of the map and the applet moves the map accordingly. If needed, it will go out to the database and retrieve additional information in order to fill the area with a world map

The fourth magnifying glass in figure 10.12 lets you highlight a box on the map. This highlighted area then expands to fill the entire map area. The fifth magnifying glass in figure 10.12 brings up a dialog box that displays the latitude and longitude of the point on the map under the mouse pointer. It also uses a drop-down list box to allow the user to change the magnification. The sixth magnifying glass lets you add a URL to the map, and the seventh lets you change the colors used to display various items and even turn off the display of some items.

Drop-down lists at the top of the map let you go to certain areas and select the resolution of the map. Resolution is discussed in more detail below..

Map source

Digital Chart of the World (DCW) is used for the mapping data. The server will actually support any Vector Product Format (VPF) database, but currently the only VPF database that is public is the DCW database. All five DCW libraries are now on-line.

Can I get a copy of the server?

No. The source code to the applet is available, but neither the VPF library nor the server is available to the public. However, this does not prevent you from using the Map applet on your Web page; it can be used without having the server source code. The HTML code to do this is shown below.

Sample HTML code

Use the following HTML code to include the Map applet in your Web page:

<applet codeBASE="http://maps.purple.org/map" CODE="MapApplet.class"

    WIDTH=460 HEIGHT=340>
<PARAM NAME=LAT VALUE="45.0">
<PARAM NAME=LON VALUE="-90.0">
<PARAM NAME=SCALE VALUE="2">
</APPLET>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameters you can use with the Map applet are as follows:

lat This is the latitude of the center point of the map.

lon This is the longitude of the center point of the map.

scale This is the size of the map. Size 2 is the default. A larger number displays a smaller area.

What does accuracy do

The accuracy menu controls how many points are sent to the client. Point clipping is used to reduce the huge amount of data involved when sending the vectors to the client. This is very helpful for people using 28.8 modems. For example, in World View, 290K of data is used to send all the points with full accuracy selected, 118K with the default medium, and only 67K when in poor accuracy mode.

10.1.12 Modem

Modem is a simple applet that displays a picture of an external computer modem on the screen, complete with flashing lights (figure 10.13). The flashing lights do not have any meaning. That is, they do not correspond to underlying functions being performed by the computer. Figure 10.14 shows the Modem sample Web page from the CD that comes with this book.

Sample HTML code

Use the following HTML code to include Modem in your Web page:

<applet code="Modem" width=30 height=10>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, Modem does not use parameters. The correct size for the applet is 30 x 10. No other size is useful.

10.1.13 Moire Patterns

A Moire pattern occurs when two similar, repeating patterns are almost but not quite superimposed. The Moire pattern is a kind of interference pattern. The basic pattern consists of lines radiating out from a common center. One copy of this pattern is fixed, and the other drifts about, creating a changing interference pattern.

Moire patterns can be very hypnotic and is not unusual for people to stare at them for long periods of time. While this can help grab attention for your Web site, it can also direct attention away from your message. For this reason, you should use Moire patterns with care when looking to attract attention.

The Moire Patterns applet allows you to display and manipulate moire patterns on your Web site (figure 10.15). Using the built-in controls, you can select the background along with its size and spacing, the foreground along with its size and spacing, and the rotation and its step. For background, you can choose among concentric circles, radial lines, parallel lines, or trigrid lines. For the foreground, you can choose between parallel lines or trigrid lines.

Sample HTML code

Use the following HTML code to include Moire Patterns in your Web page:

<applet code="Moire.class" width=512 height=384>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, Moire Patterns does not use parameters.

10.1.14 Moire1

Moire1 displays moire patterns on the screen (figure 10.16). You can start and stop the applet by shift-clicking on the pattern. You can also click-and-drag to control the motion of the pattern yourself. Moire1 is highly configurable with respect to the color of the lines, the background, and the border. Figure 10.17 shows the Moire1 sample Web page from the CD that comes with this book.

Sample HTML code

Use the following HTML code to include Moire1 in your Web page:

<applet code="Moire1.class"  height=200 width=200>

<param name="bgColor" value="yellow">

<param name="lineColor" value="0 180 0">

</applet>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameters you can use with Moire1 are as follows:

bgcolor This is the background color, specified by giving the name of the color.

linecolor This is the color for the lines used to construct the moire pattern, specified using decimal values separated by spaces.

10.1.15 The Particle Tree

The Particle Tree draws rough drawings of trees using a technique based loosely on particle systems (figure 10.18). Obviously, Particle Tree is not an applet with general uses.

Figure 10.19 shows the Particle Tree sample Web page from the CD that comes with this book.

Sample HTML code

Use the following HTML code to include the Particle Tree in your Web page:

<applet code="particleTree.class" WIDTH=200 HEIGHT=300>

</APPLET>

Parameters

Other than the usual height, width, code, and codebase parameters, the Particle Tree does not use parameters.

10.1.16 The Poetry Gallery

If you are running a Web site devoted to poetry or writing, then you are going to want to include a copy of the Poetry Gallery applet as a fun diversion. When it starts, The Poetry Gallery displays a screen similar to the one in figure 10.20. This screen has a collection of words and phrases placed individually on blocks. You can rearrange these blocks to write poetry, or anything else for that matter. To remove extra blocks, just drag them off the applet area. Figure 10.21 shows several poems written with The Poetry Gallery.

Sample HTML code

Use the following HTML code to include The Poetry Gallery in your Web page:

<applet code="PoetryApplet" height=425 width=500>

</applet>

Parameters

The Poetry Gallery does not use any parameters other than the usual height, width, code, and codebase parameters.

10.1.17 Simple 3-D Viewer

This applet reads and displays three dimensional files in the OFF file format, one of the file formats used by the Geometry Center 3-D viewer Geomview. Two views of the same 3-D object are shown in figure 10.22. To rotate the object, you simply click on it and drag it. You can move objects along any of three axes. Simple 3-D Viewer uses the painter's algorithm for polygonal sorting, which often does not produce a correct rendering so objects may appear less than perfect.

Unless you are running Geomview or are a 3-D modeling whiz, you would find this applet to be of limited use. It is nearly impossible to find OFF-format objects on the Web except in the Geomview software package.

There are two versions of this applet, one embedded and one not. The above describes the not embedded version. The embedded version does not open a separate window in the browser.

Sample HTML code

Use the following HTML code to include Simple 3-D Viewer in your Web page:

<applet code="ThreeD.class" width=0 height=0>

</applet>

Parameters

Other than the usual height, width, code, and codebase parameters, Simple 3-D Viewer does not use parameters.

10.1.18 Stars Applet

The Stars Applet displays a moving star field against a black background. It is similar to a popular screen saver option in Windows 95. You can't do much with Stars Applet, but it's so pretty (figure 10.23)! Be sure to click the mouse on the stars. Figure 10.24 shows the Stars Applet sample Web page from the CD that comes with this book.

Sample HTML code

Use the following HTML code to include Stars Applet in your Web page:

<applet code=StarField.class  WIDTH=500 HEIGHT=500>

<PARAM NAME=STARS VALUE=200>

<PARAM NAME=SPEED VALUE=15>

</APPLET>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameters you can use with Stars Applet are as follows:

stars This is the total number of stars to display.

speed This is the thread delay for each iteration, in milliseconds.

type This is the type of star field. There are two types: 0, which has small stars, and 1, which has larger stars.

10.1.19 TimeGraph

The TimeGraph applet is useful for displaying graphs of dynamic data, such as network or Web server statistics. The applet can display up to eight graphs at the same time. The program recalibrates its scale automatically to fit the data. There is a zoom function so you can inspect parts of the graph in more detail (figure 10.25). Figure 10.26 shows the TimeGraph sample Web page from the CD that comes with this book.

Syntax for both the TimeGraph applet parameters and for the statistics file are rather tricky. Read the documentation carefully.

The statistics file format

The data for the graph is displayed in a separate ASCII file. This allows you to update the graph without having to modify the underlying HTML file. Each line in the statistics file represents a single set of statistics at a specific time, for a number of different groups of parameters. Each group represents one entityÑfor example, an individual link to another siteÑand within each group is a number of different parameters. It is possible to use this applet to display data dynamically (on the fly), but in order to do that you need a dynamic data source, say from a CGI program. The author's documentation explains how to do this.

The timestamp is separated from the groups by white space (one or more spaces or tabs), and the groups are also separated from each other by white space. The end-of-line character signifies that there are no more statistics from that point in time.

The timestamp takes the format "HH:MM Day dd/mm/yy". To use U.S.-style dates, 19:20 Sun 03/17/96, use the usdates applet parameter. Each group looks like:


name="groupname",param=value[,param=value...]

Each group must have a name string parameter, and all the parameters apart from the name must be numeric, either in floating-point or integer representations. Scientific notation is not supported. Figure 10.27 shows the top of the data file used to create the graph shown in figure 10.25.

Sample HTML code

Use the following HTML code to include TimeGraph in your Web page:

<applet code="TimeGraph.class" width=500 height=300>

<param name="cabbase" value="TimeGraph.cab">

<param name="src" value="Dublin-Inet">

</applet>

Parameters

In addition to the usual height, width, code, and codebase parameters, the parameters you can use with TimeGraph are as follows:

src This is the name of the statistics file.

graph# This specifies which series to graph where # takes on the graph number 1-8.

markdaytime This parameter causes the applet to differentiate between night and day, where daytime is between 8 a.m. and 6 p.m.

markweekend This parameter cause the applet to differentiate between week and weekend.

usdates This parameter causes the applet to expect U.S.-format dates in the form of mm/dd/yy instead of dd/mm/yy.

memory This parameter is used for dynamic data sources. It causes the applet to only retain the specified number of the most recent data points.

10.1.20 Trees and Ferns

The Trees and Ferns applet draws pretty reasonable looking trees and ferns (figure 10.28) using an LGrammer algorithm. In addition, the applet is double-buffered to prevent flickering and multithreaded. One thread is solely responsible for drawing the tree or fern in an off-screen buffer. The main thread handles user interface and periodically copies whatever the other thread has finished out of the off-screen buffer and plops it into the main window.

Sample HTML code

Use the following HTML code to include Trees and Ferns in your Web page:

<applet code="LGrammer.class" WIDTH=300 HEIGHT=310>

</APPLET>

Parameters

Other than the usual height, width, code, and codebase parameters, Trees and Ferns does not use parameters.

Support

Here are links to home sites for the applets discussed in Java Applets and Channels Without Programming.

Check links for licensing information with respect to applets not included on the CD-ROM. At the time of publication, the applets described in the book were free for non-commercial use. Things change, however.

When an applet name is "unlinked" it means that a web presence for the applet has not been available for quite some time. Moreover, many (or most) of the links listed here have gone out of service. Recall that Java Applets and Channels Without Programming appeared in the early days of Java applet development. As time passes, fewer and fewer of the applets described in the book are maintained on the Web by their authors. You may have luck finding current or new homes for some of these applets through various web search engines.

Readers who wish to ask questions, reports bugs, or submit usage hints should send mail to the Manning Publications webmaster.

Chapter 3: Changing The Way Text Is Displayed

Chapter 4: Ticker Tape Type Text Displays

Chapter 5: Lines, Buttons, Bullets, And Counters With Java
          Lines
          Buttons
          Bullets
          Counters

Chapter 6: Date And Time Applets
Calendars

Chapter 7: Working With Links And E-Mail
Links
EMail

Chapter 8: Working With Images And Animation
Images
Animation

Chapter 9: Kid's Stuff
Games

Chapter 10: Miscellaneous

Chapter 11: Major Applets

Links to More Applets