第三十八章. Eclipse 插件

若要完全覆盖现有 Eclipse 文件，请执行clean任务和其相应的生成任务，例如gradle cleanEclipse eclipse (按此顺序)。如果你想要让它成为默认行为，请将tasks.eclipse.dependsOn(cleanEclipse)添加到构建脚本。这样一来，我们就没有必要显式执行 clean 任务。
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.

一个完全覆盖会导致现有的所有内容被丢弃，从而丢失在 IDE 中直接做的任何修改。另外， beforeMerged hook 可以实现只覆盖现有的某些部分的内容。下面的示例从Classpath域对象中删除现有的所有依赖关系:
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' }
    }
}

生成的.classpath文件将只包含 Gradle 生成的依赖项，而没有其他可能存在于原始文件的依赖项。(对于依赖项，这也是默认行为。)其他部分的.classpath文件将会被合并或者保留。对.project文件中的natures的处理也是一样：

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 hook 允许操作完全填充的域对象。通常，这是自定义 Eclipse 文件的首选的方法。下面的例子展示了如何导出一个 Eclipse 项目的所有依赖项：
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 hook 允许在文件写入到磁盘之前，操纵内存中的 XML 的表示形式。尽管 Groovy 的 XML 支持对其有很大作用，但这种方法比起操纵域对象依然不大方便 。作为回报，你可以对生成的文件进行全面的控制，包括未由域对象建模的那些部分。
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'
}