無法在項目 grpc_hello_server 上執行目標 org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile)：編譯失敗

Question

我正在嘗試使用下面的代碼實驗室創建一個帶有 Java 的 gRPC 服務。 我創建了一個示例原型文件。 使用 maven 編譯 .proto 時，出現構建失敗錯誤。 它說 javax.annotation.Generated 注釋 class 未找到。

你能幫我找到問題的根本原因和解決問題的步驟嗎？ 我覺得這應該是一個版本控制問題，但不清楚如何解決它。

https://codelabs.developers.google.com/codelabs/cloud-grpc-java/index.html?index=..%2F..index#2

錯誤：

[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /home/grpc_hello_server/target/generated-sources/protobuf/grpc-java/com/example/grpc/GreetingServiceGrpc.java:[20,18] cannot find symbol
  symbol:   class Generated
  location: package javax.annotation
[INFO] 1 error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  9.845 s
[INFO] Finished at: 2020-06-29T16:56:21-07:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project grpc_hello_server: Compilation failure
[ERROR] /home/grpc_hello_server/target/generated-sources/protobuf/grpc-java/com/example/grpc/GreetingServiceGrpc.java:[20,18] cannot find symbol
[ERROR]   symbol:   class Generated
[ERROR]   location: package javax.annotation
[ERROR]
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException.  

pom.xml

  <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example.grpc</groupId>
  <artifactId>grpc_hello_server</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>grpc_hello_server</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-netty</artifactId>
        <version>1.7.0</version>
    </dependency>

    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-protobuf</artifactId>
        <version>1.7.0</version>
    </dependency>

    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-stub</artifactId>
        <version>1.7.0</version>
    </dependency>
  </dependencies>
  <properties>
    <maven.compiler.source>1.6</maven.compiler.source>
    <maven.compiler.target>1.6</maven.compiler.target>
  </properties>
  <build>
      <extensions>
          <extension>
              <groupId>kr.motd.maven</groupId>
              <artifactId>os-maven-plugin</artifactId>
              <version>1.6.2</version>
          </extension>
      </extensions>
      <plugins>
          <plugin>
              <groupId>org.xolstice.maven.plugins</groupId>
              <artifactId>protobuf-maven-plugin</artifactId>
              <version>0.5.0</version>
              <configuration>
                  <protocArtifact>com.google.protobuf:protoc:3.4.0:exe:${os.detected.classifier}</protocArtifact>
                  <pluginId>grpc-java</pluginId>
                  <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.7.0:exe:${os.detected.classifier}</pluginArtifact>
              </configuration>
              <executions>
                  <execution>
                      <goals>
                          <goal>compile</goal>
                          <goal>compile-custom</goal>
                      </goals>
                  </execution>
              </executions>
          </plugin>
      </plugins>
  </build>
</project>

Answer 1

您使用 Java 1.6 的任何原因？

    <maven.compiler.source>1.6</maven.compiler.source>
    <maven.compiler.target>1.6</maven.compiler.target>

你能把它改成1.7，看看它是否有效？

Answer 2

問題是由於在 pom.xml 中缺少 Java 9+ 的依賴項

    <dependency> <!-- necessary for Java 9+ -->
        <groupId>org.apache.tomcat</groupId>
        <artifactId>annotations-api</artifactId>
        <version>6.0.53</version>
        <scope>provided</scope>
    </dependency>