ManifestClassPath Task

## Manifestclasspath

Since Apache Ant 1.7

### Description

Converts a Path into a property whose value is appropriate for a Manifest's `Class-Path` attribute.

This task is often used to work around command line limitations on Windows when using very long class paths when launching an application. The long class path normally specified on the command line is replaced by a single (possibly empty) jar file which an in-manifest `Class-Path` attribute whose value lists all the jar and zip files the classpath should contain. The files referenced from this attribute must be found relatively to the jar file itself, usually in the same directory. JVM automatically uses all file entries listed in the `Class-Path` attributes of a jar to locate/load classes. Note though that it silently ignores entries for which it cannot find any corresponding file.

Note that the property value created may be longer than a manifest's maximum 72 characters per line, but will be properly wrapped as per the Jar specification by the `<manifest>` element, where the defined property is re-referenced.

For this task to work properly the relative path from the file given in the `jarfile` attribute to the elements of the nested `classpath` must be the same as you expect them to be when deploying the jar.

### Parameters

Attribute | Description | Required
--- | --- | ---
property | the name of the property to set. This property must not already be set. | Yes
jarfile | the filename for the Jar which will contain the manifest that will use the property this task will set. This file need not exist yet, but its parent directory must exist. | Yes
maxParentLevels | The maximum number of parent directories one is allowed to traverse to navigate from the jar file to the path entry. Put differently, the maximum number of .. which is allowed in the relative path from the jar file to a given class path entry. Specify 0 to enforce a path entry to be in the same directory (or one of its sub-directories) as the jar file itself. | No; defaults to 2

### Parameters specified as nested elements

#### classpath

A path-like element, which can be defined in-place, or refer to a path defined elsewhere using the `<classpath refid="pathid"/>` syntax. This classpath must not be empty, and is required.

### Examples

Assuming a path with id=classpath was already defined, convert this path relatively to the `build/` directory that will contain `acme.jar`, which can later be created with `<jar>` with a nested `<manifest>` element that lists an `<attribute name="Class-Path" value="${jar.classpath}"/>`.

    <manifestclasspath property="jar.classpath"
                       jarfile="build/acme.jar">
        <classpath refid="classpath"/>
    </manifestclasspath>