Gradle执行Java类（不修改build.gradle）

问题描述

有运行Gradle，它只是使用命令行方式来启动gradle。

maven编译和运行的gradle模拟是什么
使用 JavaExec 。举例如下： build.gradle

  task execute（类型：JavaExec）{
 main = mainClass 
 classpath = sourceSets.main.runtimeClasspath 
} 
  

运行 gradle -PmainClass = Boo执行。你得到

  $ gradle -PmainClass = Boo执行
：compileJava 
：compileGroovy UP-TO-DATE 
：processResources UP-TO-DATE 
：类
：执行
我是BOO！ 
  

mainClass 是一个属性，命令行。 classpath 设置为拾取最新的类。

如果不传入

  $ gradle execute 
 
失败：生成失败，出现异常。 
 
 *其中：
构建文件'xxxx / build.gradle'行：4 
 
 *出错：
评估根项目时出现问题富。 
>无法在任务'execute'上找到属性'mainClass'。 
  

更新来自评论：

在Gradle中没有 mvn exec：java 等价，您需要应用应用程序插件或者执行JavaExec任务。

There is simple Eclipse plugin to run Gradle, that just uses command line way to launch gradle.

What is gradle analog for maven compile and runmvn compile exec:java -Dexec.mainClass=example.Example

This way any project with gradle.build could be run.

UPDATE: There was similar question What is the gradle equivalent of maven's exec plugin for running Java apps? asked before, but solution suggested altering every project build.gradle

package runclass;

public class RunClass {
    public static void main(String[] args) {
        System.out.println("app is running!");
    }
}

Then executing gradle run -DmainClass=runclass.RunClass

:run FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':run'.
> No main class specified

解决方案

Use JavaExec. As an example put the following in build.gradle

task execute(type:JavaExec) {
   main = mainClass
   classpath = sourceSets.main.runtimeClasspath
}

To run gradle -PmainClass=Boo execute. You get

$ gradle -PmainClass=Boo execute
:compileJava
:compileGroovy UP-TO-DATE
:processResources UP-TO-DATE
:classes
:execute
I am BOO!

mainClass is a property passed in dynamically at command line. classpath is set to pickup the latest classes.

If you do not pass in the mainClass property, this fails as expected.

$ gradle execute

FAILURE: Build failed with an exception.

* Where:
Build file 'xxxx/build.gradle' line: 4

* What went wrong:
A problem occurred evaluating root project 'Foo'.
> Could not find property 'mainClass' on task ':execute'.

UPDATED from comments:

There is no mvn exec:java equivalent in gradle, you need to either apply the application plugin or have a JavaExec task.

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