Docker启动springboot项目并报告java版本错误

Question

我使用下面的dockerfile生成一个图像调用userservice

FROM java:8-alpine
COPY ./userservice.jar /tmp/userservice.jar
ENTRYPOINT java -jar /tmp/userservice.jar

然后我使用以下命令运行容器

Exception in thread "main" java.lang.UnsupportedClassVersionError: com/imortal/UserApplication has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:151)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:46)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:107)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:88)

所以我去检查编译的字节码版本，确实是52，我不知道为什么这个错误还是报告

javap -verbose .\UserApplication.class
public class com.imortal.UserApplication
minor version: 0
major version: 52
flags: (0x0021) ACC_PUBLIC, ACC_SUPER
this_class: #2                          // 
com/imortal/UserApplication
super_class: #4                         // java/lang/Object
interfaces: 0, fields: 0, methods: 2, attributes: 2

Answer 1

使用具有兼容jdk版本的docker映像，这样它就不会与您所拥有的所有微服务产生任何冲突。出现此问题可能是因为您的一个微服务构建在其他jdk版本上。