java - 无效的目标版本 : 12 when pushing the heroku repo

Question

每当我 git push heroku master 时都会出错，这就是错误

无法在项目后端执行目标 org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile): fatal error 编译:无效目标版本:12

我不确定为什么这个错误不断出现，我想我用我的 pom.xml 文件修复了它，但似乎我做错了什么

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.backend</groupId>
    <artifactId>backend</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>12</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>webjars-locator-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>sockjs-client</artifactId>
            <version>1.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>stomp-websocket</artifactId>
            <version>2.3.3</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>3.3.7</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
        <groupId>com.google.firebase</groupId>
        <artifactId>firebase-admin</artifactId>
        <version>6.10.0</version>
        </dependency>
        <dependency>
        <groupId>org.quartz-scheduler</groupId>
        <artifactId>quartz-jobs</artifactId>
        <version>2.2.1</version>
        </dependency>
    </dependencies>

    <build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
             <configuration>
                <release>12</release>
            </configuration>
        </plugin>
    </plugins>
   </build>
</project>

请告诉我如何解决这个问题。

谢谢

Answer 1

您需要在项目的根目录中创建一个名为system.properties 的文件，其中包含以下行:

java.runtime.version=12

但是，Heroku 不支持运行时版本 12，仅支持奇数(在撰写本文时为 11、13、15)。参见 https://devcenter.heroku.com/articles/java-support#supported-java-versions

确保您的 pom.xml 和 system.properties 都针对相同的版本，否则会很头疼。