从Eclipse向上游推送到Heroku服务器失败

我能够提交更改，但当我向上游推进时，我得到的信息是：

Repository git@heroku.com:protected-garden-XXXX.git

pre-receive hook declined
Compressing source files... done.
Building source:

-----> Java app detected
-----> Installing OpenJDK 1.6... done
-----> Installing Maven 3.3.1... done
-----> Executing: mvn -B -DskipTests=true clean install
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/maven/cli/MavenCli : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:401)
    at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:254)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
    at org.codehaus.plexus.classworlds.launcher.Launcher.getMainClass(Launcher.java:144)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:266)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)

 !     ERROR: Failed to build app with Maven
       We're sorry this build is failing! If you can't find the issue in application code,
       please submit a ticket so we can help: https://help.heroku.com/


 !     Push rejected, failed to compile Java app

Verifying deploy...

!   Push rejected to protected-garden-XXXX.

---

因为我使用了默认示例Eclipse>>>项目>>>：从模板创建Heroku应用程序，选择嵌入式Jetty Servlet应用程序，只更改HelloServlet第20行中的文本，然后提交，所以可能会出现什么问题。

Heroku支持团队的回答：解决了我的问题

Heroku使用Maven 3构建带有pom.xml文件的项目，它不会在任何版本的Java 6上运行。它需要Java7或更高版本。就我个人而言，我建议直接使用最新版本Java 8，因为Oracle或OpenJDK团队不再支持Java 7

您可以通过指定

java.runtime.version=1.8

在：

system.properties 

文件，然后推送应用程序。您还需要在本地安装相同版本的Java，以便在推送应用程序之前测试应用程序