第三十八章. Eclipse 插件

要完全覆盖现有 Eclipse 文件，请执行 clean 任务及其相应的生成任务，例如 gradle cleanEclipse eclipse（按此顺序）。如果要让它成为默认行为，请添加 tasks.eclipse.dependsOn(cleanEclipse) 到构建脚本中。这样我们就不用显式执行清理任务了。
To completely overwrite existing Eclipse files, execute a clean task together with its corresponding generation task, for example gradle cleanEclipse eclipse (in that order). If you want to make this the default behavior, add tasks.eclipse.dependsOn(cleanEclipse) to your build script. This makes it unnecessary to execute the clean task explicitly.

完全覆盖同样可以用于个人文件，例如通过执行 gradle cleanEclipseClasspath eclipseClasspath。
Complete overwrite works equally well for individual files, for example by executing gradle cleanEclipseClasspath eclipseClasspath.

完全覆盖会导致现有的所有内容被丢弃，从而丢失在 IDE 中直接做的任何更改。作为另一种选择，beforeMerged 钩子使得可以只覆盖现有内容的某些部分。以下示例从 Classpath 域对象中删除现有的所有依赖：
A complete overwrite causes all existing content to be discarded, thereby losing any changes made directly in the IDE. Alternatively, the beforeMerged hook makes it possible to overwrite just certain parts of the existing content. The following example removes all existing dependencies from the Classpath domain object:

eclipse.classpath.file {
    beforeMerged { classpath ->
        classpath.entries.removeAll { entry -> entry.kind == 'lib' || entry.kind == 'var' }
    }
}

所产生的 .classpath 文件将仅包含 Gradle-generated 的依赖项，但不包含可能存在于原始文件中的任何其他依赖。（对于依赖项条目，这也是默认行为。）.classpath文件的其余部分将保持原样或合并。对 .project 文件的自然处理了是一样：

The resulting .classpath file will only contain Gradle-generated dependency entries, but not any other dependency entries that may have been present in the original file. (In the case of dependency entries, this is also the default behavior.) Other sections of the .classpath file will be either left as-is or merged. The same could be done for the natures in the .project file:

eclipse.project.file.beforeMerged { project ->
    project.natures.clear()
}

whenMerged 钩子允许操作完全填充的域对象。通常，这是自定义 Eclipse 文件的首选方法。下面的例子展示了如何导出一个 Eclipse 项目的所有依赖：
The whenMerged hook allows to manipulate the fully populated domain objects. Often this is the preferred way to customize Eclipse files. Here is how you would export all the dependencies of an Eclipse project:

eclipse.classpath.file {
    whenMerged { classpath ->
        classpath.entries.findAll { entry -> entry.kind == 'lib' }*.exported = false
    }
}

withXml钩子允许在文件写入磁盘之前操作内存中的 XML 表示形式。尽管 Groovy 的 XML 支持对其帮助很大，但这种方法比起操作域对象依然很不方便。作为回报，你可以对生成的文件进行完全的控制，包括未由域对象建模的部分。
The withXmlhook allows to manipulate the in-memory XML representation just before the file gets written to disk. Although Groovy's XML support makes up for a lot, this approach is less convenient than manipulating the domain objects. In return, you get total control over the generated file, including sections not modeled by the domain objects.

apply plugin: 'eclipse-wtp'

eclipse.wtp.facet.file.withXml { provider ->
    provider.asNode().fixed.find { it.@facet == 'jst.java' }.@facet = 'jst2.java'
}