The Java TM Tutorial

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Trail: Security in JDK 1.2

## Lesson: Implementing Your Own Permission

> This lesson demonstrates how to write a class that defines its own special permission. The basic components in this lesson include:
> 1. A sample game called TerrysGame.

> 2. A class called HighScore, which is used by `TerrysGame` to store a user's latest high score.

> 3. A class called HighScorePermission, which is used to protect access to the user's stored high score value.

> 4. A user's security policy file, which grants permission to `TerrysGame` to update his/her high score.
> The basic scenario is as follows:
> 1. A user plays `TerrysGame`.

> 2. If the user reaches a new high score, `TerrysGame` uses the `HighScore` class to save this new value.

> 3. The `HighScore` class looks into the user's security policy to check if `TerrysGame` has permission to update the user's high score value.

> 4. If `TerrysGame` has permission to update the high score, then the HighScore class updates that value.

> We describe the key points of each of the basic components and then show a sample run:

> - TerrysGame

> - The HighScore Class

> - The HighScorePermission Class

> - A Sample Policy File

> - Putting It All Together

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