如何从命令行向gradle询问属性的值? [英] How can I ask gradle for the value of a property from the command line?

问题描述

例如，如果我希望shell脚本能够获取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，并让它将属性值(而不是其他值)打印到stdout.

For example, if I wanted a shell script to be able to get the value of rootProject.name, how could I do this? Ideally, I'd like to invoke ./gradlew with some set of arguments and have it print the property value (and nothing else) to stdout.

推荐答案

为清楚起见，这是我的Gradle包装器版本:

For clarity, here is my Gradle wrapper version:

$ ./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，可让您了解可用的属性:

This is an existing task to give you an idea of the properties available:

$ ./gradlew properties


> Task :properties

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

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

这是我用来打印项目属性的自定义任务

Here is a custom task I've built to print out a project property

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)

这就是我如何使用带有--prop参数(由@Option(option = 'prop'表示.)的自定义任务.我正在使用-q(安静)Gradle选项来抑制一些额外的输出.

And this is how I use my custom task with a --prop parameter (indicated by @Option(option = 'prop'. I'm using the -q (quiet) Gradle option to suppress some of the extra output.

$ ./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.

Because we are throwing a GradleException when we can't find the property, in Bash you can check the return code of the command to know when to parse out the value. The formatting of a successful output is up to you and you could make it easily parsed.

$ ./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中获得一个非零的返回码，并且我们知道我们不需要尝试解析出该值:

In case of a failure like the one above, we get a non-zero return code in Bash, and we know we don't need to try and parse out the value:

$ echo $?
1

不幸的是，我不知道Gradle中仅提供 的简单方法来将您关心的值提供给stdout(防止进行某些解析)，但这可以帮助您实现大部分的学习具有一定的灵活性.

Unfortunately, I don't know a simple way in Gradle to only give the value you are concerned with to stdout (prevent some parsing), but this gets you most of the way there with some flexibility.

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