以Yarn模式启动Flink报错Exception in thread “main“ java.lang.NoClassDefFoundError: org/apache/hadoop/yarn/ex

启动Hadoop集群和Yarn后，使用Yarn模式启动Flink时报错：

[root@hadoop01 bin]# ./yarn-session.sh -nm test-yarn-flink
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/yarn/exceptions/YarnException
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
        at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
        at java.lang.Class.getMethod0(Class.java:3018)
        at java.lang.Class.getMethod(Class.java:1784)
        at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:650)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:632)
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.yarn.exceptions.YarnException
        at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        ... 7 more

解决方案：

下载对应的jar，按照Hadoop的版本（我的是2.7.5）下载。

https://repo.maven.apache.org/maven2/org/apache/flink/flink-shaded-hadoop-2-uber/2.7.5-8.0/

 然后放到Flink的lib目录下。

重新启动，成功。