gradle - 如何从命令行向gradle询问属性的值？

Question

例如，如果我希望shell脚本能够获得rootProject.name的值，我该怎么做？理想情况下，我想使用一些参数来调用./gradlew，并使其将属性值(以及其他所有内容)打印到stdout。

Answer 1

为了清楚起见，这是我的Gradle包装器版本:

$ ./gradlew --version

------------------------------------------------------------
Gradle 5.4.1
------------------------------------------------------------

Build time:   2019-04-26 08:14:42 UTC
Revision:     261d171646b36a6a28d5a19a69676cd098a4c19d

Kotlin:       1.3.21
Groovy:       2.5.4
Ant:          Apache Ant(TM) version 1.9.13 compiled on July 10 2018
JVM:          11.0.2 (Oracle Corporation 11.0.2+9-LTS)
OS:           Mac OS X 10.14.4 x86_64

这是一项现有任务，可让您大致了解可用的属性:

$ ./gradlew properties


> Task :properties

------------------------------------------------------------
Root project
------------------------------------------------------------

allprojects: [root project 'myProject', project ':otherProject', ...]
...
rootDir: /path/to/rootDir
rootProject: root project 'myProject'
...
version: 2.3.0
...

这是我为打印项目属性而构建的自定义任务

class ResolveProperties extends DefaultTask {

  @Input
  String prop

  ResolveProperties() {
    // if no --prop=<property> is provided, default to spitting out all properties
    prop = "properties"
  }

  @Option(option = 'prop', description = 'Set the property to be evaluated for the project.')
  void setProp(final String prop) {
    this.prop = prop
  }

  @TaskAction
  void resolveProp() {
    List<String> propPath = this.prop.tokenize('.')
    int n = propPath.size()
    def currentProp = project
    propPath.eachWithIndex { p, i ->
        if(currentProp.hasProperty(p)) {
          currentProp = currentProp.property(p)
        }
        else {
          throw new GradleException("failed to resolve property: ${this.prop}")
        }
    }
    println "${this.prop} -> ${currentProp}"
  }
}

task resolveProperties(type: ResolveProperties)

这就是我将自定义任务与 --prop参数(由 @Option(option = 'prop'指示)一起使用的方式。我正在使用 -q(安静)Gradle选项来抑制一些额外的输出。

$ ./gradlew -q resolveProperties --prop=rootProject.name
rootProject.name -> onestop
resolveProperties took 0 seconds
$ ./gradlew -q resolveProperties --prop=rootProject.version
rootProject.version -> 2.3.0
resolveProperties took 0 seconds
$ ./gradlew -q resolveProperties --prop=rootProject.group
rootProject.group -> org.cedar.onestop
resolveProperties took 0 seconds

由于找不到属性时会抛出 GradleException，因此在Bash中，您可以检查命令的返回码以了解何时解析该值。成功输出的格式取决于您，您可以轻松对其进行解析。

$ ./gradlew -q resolveProperties --prop=does.not.exist
resolveProperties took 0 seconds

FAILURE: Build failed with an exception.

* Where:
Build file '/Users/elliott/Documents/GitHub/onestop/build.gradle' line: 259

* What went wrong:
Execution failed for task ':resolveProperties'.
> failed to resolve property: does.not.exist

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 0s

如果发生类似上面的失败，我们将在Bash中得到一个非零的返回码，并且我们知道我们不需要尝试解析出该值:

$ echo $?
1

不幸的是，我不知道Gradle中是否有一种简单的方法仅将您关心的值提供给 stdout(防止进行某些解析)，但是这可以使您获得大部分灵活性。