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Trail: Deployment
Lesson: Packaging Programs in JAR Files
Packaging Programs in JAR Files
Using JAR Files: The Basics
Creating a JAR File
Viewing the Contents of a JAR File
Extracting the Contents of a JAR File
Updating a JAR File
Running JAR-Packaged Software
Working with Manifest Files: The Basics
Understanding the Default Manifest
Modifying a Manifest File
Setting an Application's Entry Point
Adding Classes to the JAR File's Classpath
Setting Package Version Information
Sealing Packages within a JAR File
Signing and Verifying JAR Files
Understanding Signing and Verification
Signing JAR Files
Verifying Signed JAR Files
Using JAR-related APIs
The JarClassLoader Class
The JarRunner Class
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Working with Manifest Files: The Basics

> JAR files support a wide range of functionality, including electronic signing, version control, package sealing, and others. What gives a JAR file this versatility? The answer is the JAR file's manifest.

> The manifest is a special file that can contain information about the files packaged in a JAR file. By tailoring this "meta" information that the manifest contains, you enable the JAR file to serve a variety of purposes.

> This lesson will explain the contents of the manifest file and show you how to work with it, with examples for the basic features:

### Understanding the Default Manifest

> When you create a JAR file, a default manifest is created automatically. This section describes the default manifest.

### Modifying a Manifest File

> This section shows you the basic method of modifying a manifest file. The later sections demonstrate specific modifications you may want to make.

### Setting an Application's Entry Point

> This section describes how to use the `Main-Class` header in the manifest file to set an application's entry point.

### Adding Classes to the JAR File's Classpath

> This section describes how to use the `Class-Path` header in the manifest file to add classes in other JAR files to the classpath when running an applet or application.

### Setting Package Version Information

> This section describes how to use the package version headers in the manifest file.

### Sealing Packages within a JAR File

> This section describes how to seal packages within a JAR file by modifying the manifest file.

### Additional Information

> A specification of the manifest format is part of the on-line JDK documentation.

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