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Let's Play! - Java Tutorial 5.0 英文版

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Trail: Putting It All Together
Lesson: BINGO!

Let's Play!

To play BINGO by yourself, you need follow all of the steps outlined in this section to run both the Game application and the Player application. The Game application allows many Player applications, running anywhere on your network, to register for games. So, if you wish to play against other people, invite them to play using the Game application that you start. After you've completed steps 1 through 5, all players need to follow steps 6, 7, and 8.

Both the Game and the Player applications use Swing components. You can use either JDK 1.2 or JDK 1.1 to compile and run these programs. This section includes instructions for both releases. Using JDK 1.2 is a bit simpler because it already includes the Swing components. If you are using JDK 1.1, you need to add the JFC/Swing release to your JDK release. To do so, follow the steps outlined in Getting Started with Swing to download the Swing release and to set up your environment. . The JDK 1.1 instructions in the following steps require these environment variables. Additionally, these instructions assume that your PATH environment variable includes the path to the bin directory of your JDK release.

Here are the steps required to build and play BINGO.

• Step 1: Download the Source
• Step 2: Compile the Source
• Step 3: Run rmiregistry
• Step 4: Run the Game
• Step 5: Start the Games
• Step 6: Run the Player
• Step 7: Join the Next Game
• Step 8: Play

Step 1: Download the Source

More than 50 source files in three directories compose this example. For your convenience, we include a downloadable zip archive that contains all of the source files necessary to build the BINGO Game and Player applications.

Compressed / Uncompressed	FTP Download
38 KB / 109 KB	tut-bingo.zip

After you download and unzip tut-bingo.zip, you should see a directory named example-swing whose structure is shown in the following figure:

             example-swing
                   |
       +-----------+-----------+--------------+---------------+
       |                       |              |               |
     bingo                bingo.policy     chit.gif     invisible.gif
       |
+------+--------+
|      |        |
game  player  shared

[PENDING: replace with real, non-ASCII, diagram]

The game, player, and shared directories each contain a number of .java files that have not been compiled. The bingo.policy file is a security-related file required only by JDK 1.2. The two .gif files are images that the Player application displays on BINGO cards.

Step 2: Compile the Source

First, compile the sources in the bingo/game and bingo/player directories using javac.

JDK 1.2 on Solaris

javac bingo/game/*.java
javac bingo/player/*.java

JDK 1.2 on Win32

javac bingo\game\*.java
javac bingo\player\*.java

JDK 1.1 with Swing on Solaris

javac -classpath .:$SWING_HOME/swing.jar:$JAVA_HOME/lib/classes.zip bingo/game/*.java
javac -classpath .:$SWING_HOME/swing.jar:$JAVA_HOME/lib/classes.zip bingo/player/*.java

JDK 1.1 with Swing on Win32

javac -classpath .;%SWING_HOME%\swing.jar;%JAVA_HOME%\lib\classes.zip bingo\game\*.java
javac -classpath .;%SWING_HOME%\swing.jar;%JAVA_HOME%\lib\classes.zip bingo\player\*.java

The files in bingo/shared get compiled as a side effect of compiling the source files in the bingo/game and bingo/player directories. So you don't have to compile them explicitly.

Next, create the stubs files required by RMI using the rmic utility program, which lives in the same directory as javac in the JDK release. The command is the same for JDK 1.2 and JDK 1.1 and for Solaris and Win32.

rmic -d . bingo.game.RegistrarImpl

Step 3: Run rmiregistry

You need to run a utility program called rmiregistry, which creates, starts, and manages a registry of remote objects. The Game and the Player applications use remote objects to communicate. Before running rmiregistry, make sure your CLASSPATH environment variable is not set. Typically, rmiregistry is executed in the background.

Any JDK on Solaris

unsetenv CLASSPATH
rmiregistry &

Any JDK on Win32

unset CLASSPATH
start rmiregistry

If you already have rmiregistry running, you will get an error stating that port 1099 is busy. You can either kill the rmiregistry process and start a new one or, if no other Game applications are running on your machine, you can just start the game.

Step 4: Run the Game

Now, run the Game application.

JDK 1.2

java -Djava.security.policy=bingo.policy bingo.game.BINGO

JDK 1.1 with Swing on Solaris

java -classpath .:$SWING_HOME/swing.jar:$JAVA_HOME/lib/classes.zip bingo.game.BINGO

JDK 1.1 with Swing on Win32

java -classpath .;%SWING_HOME%\swing.jar;%JAVA_HOME%\lib\classes.zip bingo.game.BINGO

The command for running the Game application under JDK 1.2 specifies a security policy (implemented by a policy file) that grants permissions to the Game application. The policy file we provide, bingo.policy, removes all security restrictions. Such a permissive policy is appropriate only for testing and not for real-world use. Refer to the Security in Java 2 SDK 1.2 for a complete tutorial on security in JDK 1.2 and how to implement a more realistic security policy.

Here's a snapshot of the Game application when it first appears on the screen:

This figure has been reduced to fit on the page.
Click the image to view it at its natural size.

[PENDING: take a new picture, why does the application look so scrunched when run in 1.2?]

Step 5: Start the Games

To start the games rolling:

1. Enter the number of seconds the game should pause between calling balls. If you want a fast game with one card, 3 seconds works well. Add a couple of seconds for each additional card. If many players are playing consider using 10 - 20 seconds.
2. After the first player registers, the Game begins a count down. During the countdown period other players can register for this game. After the countdown period expires the game begins and registration closes for this game. Enter how long the countdown period should last. If you're playing alone, use 10 seconds so that there's enough time for your BINGO card to appear on screen.
3. Enter the maximum number of players allowed to play in a single game.
4. Enter the maximum number of cards each player is allowed to play in a single game.
5. Push the Let the Games Begin button.

The Game will continually serve up games until you stop them by clicking the No More New Games button (or kill the Game process). The No More New Games button tells the Game not to start any more games after the current game is finished. Pushing this button will not stop the current game.

Step 6: Run the Player

Now run the Player and instruct your friends to run the Player as well.

JDK 1.2

java bingo.player.Player

JDK 1.1 with Swing on Solaris

java -classpath .:$SWING_HOME/swing.jar:$JAVA_HOME/lib/classes.zip bingo.player.Player

JDK 1.1 with Swing on Win32

java -classpath .;%SWING_HOME%\swing.jar;%JAVA_HOME%\lib\classes.zip bingo.player.Player

Here's a snapshot of the Player application when it first appears on screen:

Step 7: Join the Next Game

To join the next game, follow these steps:

1. If you want, type in your name.
2. If you want, type in a different seed value. This is the value used to generate your BINGO cards. The default value is the value returned from System.currentTimeMillis when the window gets created. You will always play the same cards if you always use the same seed.
3. Type the name of the computer on your network on which the Game is running. The Player application figures out the name of the host on which the Player application is running and enters this name in the host name text field. If you are running your own Game then you can just leave this value as is. If you want to play with a Game running on another machine, type the name of that machine into the text field.
4. Choose the number of cards you'd like to play.
5. Click the Join the Next Game button.

   If you're running a Game then you should see your name appear in the player list.

   After a time, you will see one of these windows for each card you requested.

   

Step 8: Play

Periodically, the Game announces a BINGO ball. The current ball is displayed on the left side of the player's light board. The right side shows all of the balls that have been called in this game thus far.

Mark the numbers on your card as the balls are called. When you have 5 adjacent numbers marked horizontally, vertically or diagonally, push the Bingo! I Won! Bingo! button.

If you really won, the Game will stop the current game, and tell you that you've won. If not, the current game continues until somebody wins, or until the balls run out.

But wait! Don't push the Bingo! I Won! Bingo! button too often. If you "cry wolf" (push the Bingo! I Won! Bingo! button and don't have a winning card) three times, you're kicked out of the game. After all, that's very disruptive to the other players!

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