如何使用“java”命令从 gradle 执行 jar 中的主类
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How to execute a main class in a jar from gradle using the 'java' command
提问by JBT
I have these files under the <project_root>folder:
我在文件<project_root>夹下有这些文件：
./build.gradle
./build/libs/vh-1.0-SNAPSHOT.jar
./libs/groovy-all-2.1.7.jar
./src/main/groovy/vh/Main.groovy
In the build.gradlefile, I have this task:
在build.gradle文件中，我有这个任务：
task vh( type:Exec ) {
commandLine 'java -cp libs/groovy-all-2.1.7.jar:build/libs/' +
project.name + '-' + version + '.jar vh.Main'
}
The Main.groovyfile is simple:
该Main.groovy文件很简单：
package vh
class Main {
static void main( String[] args ) {
println 'Hello, World!'
}
}
After plugging in the string values, the command line is:
插入字符串值后，命令行为：
java -cp libs/groovy-all-2.1.7.jar:build/libs/vh-1.0-SNAPSHOT.jar vh.Main
If I run the command directly from shell, I get correct output. However, if I run gradle vh, it will fail. So, how do I make it work? Thank you very much.
如果我直接从 shell 运行命令，我会得到正确的输出。但是，如果我运行gradle vh，它将失败。那么，我该如何让它发挥作用呢？非常感谢。
采纳答案by Peter Niederwieser
Exec.commandLineexpects a listof values: one value for the executable, and another value for each argument. To execute Java code, it's better to use the JavaExectask:
Exec.commandLine需要一个值列表：可执行文件的一个值，每个参数的另一个值。要执行 Java 代码，最好使用以下JavaExec任务：
task vh(type: JavaExec) {
main = "vh.Main"
classpath = files("libs/groovy-all-2.1.7.jar", "build/libs/${project.name}-${version}.jar")
}
Typically, you wouldn't have to hardcode the class path like that. For example, if you are using the groovyplugin, and groovy-allis already declared as a compiledependency (and knowing that the second Jar is created from the mainsources), you would rather do:
通常，您不必像那样对类路径进行硬编码。例如，如果您正在使用groovy插件，并且groovy-all已经声明为compile依赖项（并且知道第二个 Jar 是从main源创建的），您宁愿这样做：
classpath = sourceSets.main.runtimeClasspath
To find out more about the Execand JavaExectask types, consult the Gradle Build Language Reference.
要了解有关任务类型Exec和JavaExec任务类型的更多信息，请参阅Gradle 构建语言参考。
