将Maven插件升级到Java 11

Question

我正在将我的Maven构建的Java 8应用程序升级到Java 11。在我的POM中，我指定:

<properties>
  <java.version>1.11</java.version>
  <maven.compiler.source>${java.version}</maven.compiler.source>
  <maven.compiler.target>${java.version}</maven.compiler.target>
</properties>

当我使用普通的Maven构建调用来构建我的应用程序时:

mvn verify -Plocal -Dspring-boot.run.jvmArguments="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005"

我得到：

[INFO] Scanning for projects...
[INFO] 
[INFO] -----------------------< example.com:myapp-svc >------------------------
[INFO] Building myapp-svc 1
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-checkstyle-plugin:3.1.2:check (validate) @ myapp-svc ---
[WARNING] Old version of checkstyle detected. Consider updating to >= v8.30
[WARNING] For more information see: https://maven.apache.org/plugins/maven-checkstyle-plugin/examples/upgrading-checkstyle.html
[INFO] Starting audit...
Audit done.
[INFO] You have 0 Checkstyle violations.
[INFO] 
[INFO] --- jacoco-maven-plugin:0.8.7:prepare-agent (default) @ myapp-svc ---
[INFO] argLine set to -javaagent:/Users/myuser/.m2/repository/org/jacoco/org.jacoco.agent/0.8.7/org.jacoco.agent-0.8.7-runtime.jar=destfile=/Users/myuser/workspace/myapp-svc/target/jacoco.exec
[INFO] 
[INFO] --- maven-resources-plugin:3.1.0:resources (default-resources) @ myapp-svc ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 6 resources
[INFO] Copying 154 resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ myapp-svc ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 456 source files to /Users/myuser/workspace/myapp-svc/target/classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.076 s
[INFO] Finished at: 2021-11-12T12:52:52-05:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project myapp-svc: Fatal error compiling: error: invalid target release: 1.11 -> [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] 
[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/MojoExecutionException

因此，看起来＜code＞maven编译器插件：3.8.1

那么，我怎么知道是什么把它拉进来并使用它呢？或者如果这不是正在发生的事情，那是什么，我该如何修复它？

Answer 1

删除 1. 前缀。

<java.version>11</java.version>

从Java 9和更高版本开始，Java版本编号方案发生了变化，去掉了永不改变的< code>1。*。

有关官方文档和说明，请参阅 JEP 223：新版本字符串方案，从版本号中删除初始 1 元素部分。

引用JEP 223：

该提案从JDK版本号中删除了最初的1元素。也就是说，它表明JDK9的第一个版本将具有版本号9.0.0，而不是1.9.0。

近二十年后，很明显当前版本号方案的第二个元素是JDK的事实上的< code>$MAJOR版本号。

因此，您的POM应该使用：

<java.version>11</java.version>

顺便说一下，如果将POM中与编译器、构建和测试相关的其他部分更新为最新版本，则可以替换元素对＜code＞

因此，您的代码片段：

<properties>
  <java.version>1.11</java.version>
  <maven.compiler.source>${java.version}</maven.compiler.source>
  <maven.compiler.target>${java.version}</maven.compiler.target>
</properties>

...变成这样：

<properties>
  <java.version>11</java.version>
  <maven.compiler.release>${java.version}</maven.compiler.release>
</properties>

在我自己的作品中，我甚至没有一个< code>java.version元素。我简单地使用这个片段，指定UTF-8作为特征编码，Java 17作为编译和构建版本。

  <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <maven.compiler.release>17</maven.compiler.release>
  </properties>

随着UTF-8成为跨平台的新Java18默认值（参见JEP 400： UTF-8 by Default），将来我可能会删除第一个元素，

  <properties>
      <maven.compiler.release>17</maven.compiler.release>
  </properties>

以下是我的Apache Maven快速入门原型的修改版本，作为完整示例。

<?xml version="1.0" encoding="UTF-8"?>

<!-- Modified by Basil Bourque as of 2021-11 to use the latest versions. -->
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>work.basil.example</groupId>
    <artifactId>Quickie</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>Quickie</name>
    <url>http://www.basil.work</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.release>17</maven.compiler.release>
    </properties>

    <dependencies>

        <!-- https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>5.8.1</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.1.0</version>
                </plugin>
                <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.2.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>3.0.0-M5</version>
                </plugin>
                <plugin>
                    <artifactId>maven-jar-plugin</artifactId>
                    <version>3.2.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>3.0.0-M1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>3.0.0-M1</version>
                </plugin>
                <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
                <plugin>
                    <artifactId>maven-site-plugin</artifactId>
                    <version>3.9.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-project-info-reports-plugin</artifactId>
                    <version>3.1.2</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

Answer 2

替换<代码>