“undefined reference to JNI_GetCreatedJavaVM”和“File format not recognized”错误原因分析
如果编译时，报如下所示错误：
../../third-party/hadoop/lib/libhdfs.a(jni_helper.c.o): In function `getGlobalJNIEnv':
/root/hadoop-2.4.0-src/hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/jni_helper.c:446: undefined reference to `JNI_GetCreatedJavaVMs'
/root/hadoop-2.4.0-src/hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/jni_helper.c:505: undefined reference to `JNI_CreateJavaVM'
/root/hadoop-2.4.0-src/hadoop-hdfs-project/hadoop-hdfs/src/main/native/libhdfs/jni_helper.c:505: undefined reference to `JNI_CreateJavaVM'
是因为链接时，没有加上库文件libjvm.so。加上libjvm.so重编译，如果又遇到如下所示的错误：
../../third-party/libjvm.so: file not recognized: File format not recognized
这问题是因为libjvm.so不能被识别，libjvm.so的版本过高导致的
nm ../../third-party/libjvm.so | grep JNI_CreateJavaVM
nm: ../../third-party/libjvm.so: 不可识别的文件格式
查看nm的版本：
nm --version
GNU nm 2.16.91.0.5 20051219 (SUSE Linux)
Copyright 2005 Free Software Foundation, Inc.
本程序是自由软件；您可以按照 GNU 通用公共许可证
的条款对其进行再发行。本程序没有任何担保。
现在换成高一点的版本试试：
./nm --version
GNU nm 2.17.50.0.6-20.el5 20061020
Copyright 2005 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License. This program has absolutely no warranty.
再次执行，一切正常，需要升级GCC了，或者降低JRE或JDK的版本试试：
./nm libjvm.so | grep JNI_CreateJavaVM
00000000006307c0 T JNI_CreateJavaVM