gradle5删除左移符号支持导致无法编译

错误现象

FAILURE: Build failed with an exception.

* Where:
Script 'http://sc.dev.xxxx.com:8080/script/gateway.gradle' line: 87

* What went wrong:
A problem occurred evaluating script.
> Could not find method leftShift() for arguments [gateway_3jdkdl89l6uef4r948spaebo1$_run_closure12@13b89f08] on task ':replaceBuildInfo' of type org.gradle.api.DefaultTask.

* 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 8s

打开脚本查看第87行如下：

task replaceBuildInfo << {
    def buildFile = file("build/libs/application.yml")
    def gitVersion
    try {
        gitVersion = 'git rev-parse HEAD'.execute().text.trim()
        println 'Git commit: ' + gitVersion
    } catch (Exception e) {
        gitVersion = 'GET FAILED:' + e.getMessage()
    }
    if (buildFile.exists()) {
        def cfgContent = buildFile.getText().replaceAll("\\\$\\{commit\\}", gitVersion)
        cfgContent = cfgContent.replaceAll("\\\$\\{version\\}", v)
        buildFile.write(cfgContent)
    }
    buildFile = file("build/libs/bootstrap.yml")
    if (buildFile.exists()) {
        def cfgContent = buildFile.getText().replaceAll("\\\$\\{commit\\}", gitVersion)
        cfgContent = cfgContent.replaceAll("\\\$\\{version\\}", v)
        buildFile.write(cfgContent)
    }
}

起初以为是文件读取不到，找了另外几个项目对比项目结构，发现并无二致。
后来搜索关键字Could not find method leftShift() for arguments得到解释为 gradle4.x 就废弃了task中左移符号<<的支持，但依然能使用，在 gradle5.x 则彻底移除了左移符号<<的支持。

详见：

Gradle 5.0 Release Notes

Remove Task#leftShift · Issue #6266 · gradle/gradle

解决办法

修改原脚本

最彻底的方案当然是修改原脚本，将左移符号<<更改为doList块。如下：

// 修改前
task replaceBuildInfo << {
    def buildFile = file("build/libs/application.yml")
    def gitVersion
    try {
        gitVersion = 'git rev-parse HEAD'.execute().text.trim()
        println 'Git commit: ' + gitVersion
    } catch (Exception e) {
        gitVersion = 'GET FAILED:' + e.getMessage()
    }
    if (buildFile.exists()) {
        def cfgContent = buildFile.getText().replaceAll("\\\$\\{commit\\}", gitVersion)
        cfgContent = cfgContent.replaceAll("\\\$\\{version\\}", v)
        buildFile.write(cfgContent)
    }
    buildFile = file("build/libs/bootstrap.yml")
    if (buildFile.exists()) {
        def cfgContent = buildFile.getText().replaceAll("\\\$\\{commit\\}", gitVersion)
        cfgContent = cfgContent.replaceAll("\\\$\\{version\\}", v)
        buildFile.write(cfgContent)
    }
}
replaceBuildInfo.dependsOn(taskXxx)

// 修改后
task hello {
    dependsOn 'taskXxx'
    doLast {
      def buildFile = file("build/libs/application.yml")
      def gitVersion
      try {
          gitVersion = 'git rev-parse HEAD'.execute().text.trim()
          println 'Git commit: ' + gitVersion
      } catch (Exception e) {
          gitVersion = 'GET FAILED:' + e.getMessage()
      }
      if (buildFile.exists()) {
          def cfgContent = buildFile.getText().replaceAll("\\\$\\{commit\\}", gitVersion)
          cfgContent = cfgContent.replaceAll("\\\$\\{version\\}", v)
          buildFile.write(cfgContent)
      }
      buildFile = file("build/libs/bootstrap.yml")
      if (buildFile.exists()) {
          def cfgContent = buildFile.getText().replaceAll("\\\$\\{commit\\}", gitVersion)
          cfgContent = cfgContent.replaceAll("\\\$\\{version\\}", v)
          buildFile.write(cfgContent)
      }
  }
}

详见：
Build Script Basics

降级gradle

修改脚本固然是根本办法，但是团队开发的规范和限制也不是能一下子就突破的。固针对具体项目使用指定版本。

项目自定义版本

项目根目录下会有一个gradle文件夹
修改此文件夹下gradle/wrapper/gradle-wrapper.properties文件中distributionUrl属性

1 2	#distributionUrl=https\://services.gradle.org/distributions/gradle-5.4.1-bin.zip distributionUrl=https\://services.gradle.org/distributions/gradle-4.7-bin.zip