为什么我的 Java9 模块服务不起作用？

Question

---------------------------------------------
package org.zpf.service;
public interface Services {
    void test();
}
module org.zpf.service.Services {
    exports org.zpf.service;
}
---------------------------------------------
package org.zpf.impl;
import org.zpf.service.Services;

public class Impl implements Services {
@Override
public void test() {
    System.out.println("Impl-1");
 }
}

module org.zpf.impl.Impl {
    requires org.zpf.service.Services;
    provides org.zpf.service.Services with org.zpf.impl.Impl;
}
----------------------------------------------
public class Demo {
   public static void main(String[] args) {
      ServiceLoader.load(Services.class).forEach(Services::test);
   }
}

module org.zpf.demo.Demo {
    requires org.zpf.service.Services;
    uses org.zpf.service.Services;
}

我正在用 IntelliJ IDEA 运行这段代码，但是看起来子模块没有运行。以下是程序的输出：

/Library/Java/JavaVirtualMachines/jdk-11.0.1.jdk/Contents/Home/bin/java "-javaagent:/Applications/IntelliJ IDEA 2018.3.app/Contents/lib/idea_rt.jar=61434:/Applications/IntelliJ IDEA 2018.3.app/Contents/bin" -Dfile.encoding=UTF-8 -p /Users/tubetrue01/IDEA/Test/Demo/target/classes:/Users/tubetrue01/IDEA/Test/Services/target/classes -m org.zpf.demo.Demo/org.zpf.demo.Demo

Process finished with exit code 0

Answer 1

您需要做的就是确保模块

module org.zpf.impl  // fixing the name from that of question

存在于模块路径中。从命令行执行您共享的命令，并添加到impl 模块的路径，正如预期的那样。

.../jdk-11.jdk/Contents/Home/bin/java -p .../Desktop/modular/out/production/demo:.../Desktop/modular/out/production/modular:.../Desktop/modular/out/production/impl -m org.zpf.demo.Demo/org.zpf.demo.Demo

打印扩展输出

Impl-1

---

在您的命令行中（格式化只是为了便于阅读）

-p /Users/tubetrue01/IDEA/Test/Demo/target/classes:
   /Users/tubetrue01/IDEA/Test/Services/target/classes

应该修改成类似

-p /Users/tubetrue01/IDEA/Test/Demo/target/classes:
   /Users/tubetrue01/IDEA/Test/Services/target/classes:
   /Users/tubetrue01/IDEA/Test/Impl/target/classes

---

使用 IntelliJ IDEA，您可以执行以下步骤：

1. 项目结构 > 模块
2. 选择Demo 模块> 导航到依赖项
3. 添加依赖 [Modal 左下角 (+)] > 模块依赖
4. 选择Impl 模块并应用。
5. 现在运行Demo 课程。