如何运行akka grpc java示例

Question

好的，按照使用Java 8的先决条件和说明，项目创建工作。

sbt new akka/akka-grpc-quickstart-java.g8

然后继续使用指南

./gradlew compileJava也能工作。

但是，./gradlew --info runServer失败了，出现了折叠错误/问题：

Task ':runServer' is not up-to-date because:
Task has not declared any outputs.

和

Error: Main method not found in class com.example.helloworld.GreeterServer, please define the main method as:
   public static void main(String[] args)

原始帖子：

我在运行Akka-GRPC示例时遇到了困难。我试着跟踪这里的导游，但是当我下载示例项目时，它似乎不完整。

这就是树命令的输出：

.
├── build.sbt
├── project
│   ├── build.properties
│   └── plugins.sbt
├── sbt
├── sbt.bat
└── sbt-dist
    ├── bin
    │   ├── sbt
    │   ├── sbt.bat
    │   ├── sbt-launch.jar
    │   └── sbt-launch-lib.bash
    └── conf
        ├── sbtconfig.txt
        └── sbtopts

4 directories, 11 files

在项目结构中没有源文件或梯度pom.xml。

接下来，我克隆了来自GitHub的示例存储库并遵循了自述文件中的指令，主要是命令sbt new akka/akka-grpc-quickstart-java.g8。

$ sbt new akka/akka-grpc-quickstart-java.g8
[info] Loading settings for project akka-grpc-quickstart-java-g8-build from paradox.sbt,giter8.sbt ...
[info] Loading project definition from /home/johannes/IdeaProjects/akka-grpc-quickstart-java.g8/project
error: error while loading String, class file '/modules/java.base/java/lang/String.class' is broken
(class java.lang.NullPointerException/null)
[error] java.io.IOError: java.lang.RuntimeException: /packages cannot be represented as URI
...//had to remove stacktrace was too long for this post
[error]     at xsbt.boot.Boot.main(Boot.scala)
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore? [error] java.io.IOError: java.lang.RuntimeException: /packages cannot be represented as URI
[error] Use 'last' for the full log.

然后，我进入了项目/源文件夹。/src/main/g8/源文件所在的位置，并尝试按照指南中的说明进行操作。由于某些属性错误，这也无法工作：

在此之前，我必须在./ gradle /wrapper/gradle-wrapper.properties中设置另一个gradle版本(6.1.1，是4.5.1)，以使其与Java 13兼容。

$ ./gradlew compileJava

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'g8'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not find gradle.plugin.com.lightbend.akka.grpc:akka-grpc-gradle-plugin:$akka_grpc_version$.
     Searched in the following locations:
       - file:/home/johannes/.m2/repository/gradle/plugin/com/lightbend/akka/grpc/akka-grpc-gradle-plugin/$akka_grpc_version$/akka-grpc-gradle-plugin-$akka_grpc_version$.pom
       - https://plugins.gradle.org/m2/gradle/plugin/com/lightbend/akka/grpc/akka-grpc-gradle-plugin/$akka_grpc_version$/akka-grpc-gradle-plugin-$akka_grpc_version$.pom
     Required by:
         project :

* 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 4s

我试图至少暂时地将这些属性硬编码到build.gradle文件中：

     //classpath 'gradle.plugin.com.lightbend.akka.grpc:akka-grpc-gradle-plugin:$akka_grpc_version$'
     classpath 'gradle.plugin.com.lightbend.akka.grpc:akka-grpc-gradle-plugin:0.7.3'

但这也只让我了解到：

$ ./gradlew compileJava

FAILURE: Build failed with an exception.

* Where:
Build file '/home/johannes/IdeaProjects/akka-grpc-quickstart-java.g8/src/main/g8/build.gradle' line: 20

* What went wrong:
A problem occurred evaluating root project 'g8'.
> Failed to apply plugin [id 'com.google.protobuf']
   > Could not create an instance of type com.google.protobuf.gradle.ProtobufSourceDirectorySet.
      > 'void org.gradle.api.internal.file.DefaultSourceDirectorySet.<init>(java.lang.String, java.lang.String, org.gradle.api.internal.file.FileResolver, org.gradle.api.internal.file.collections.DirectoryFileTreeFactory)'

* 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 1s

由于字符限制，再次不能包括整个堆栈跟踪。

我遗漏了什么？我应该进一步采取哪一种方法？

Answer 1

编辑:同时，拉请求被接受，主回购(https://github.com/akka/akka-grpc-quickstart-java.g8)是最新的.

我使用sbt .下载了这个项目，但是pom.xml中有一个错误(固定版本：https://github.com/olitazl/akka-grpc-quickstart-java.g8)

示例项目的问题是在public类中缺少GreeterServer修饰符。

因此，您必须将public添加到GreeterServer类和方法main中。

    public class GreeterServer ...
    public static void main(...)

如果您重新创建您的项目从我的回购，问题也是修复那里。