编译hadoop的libhdfs.a

hadoop提供了CMake来编译libhdfs，因此在编译之前需要先安装好CMake工具。


然后进入libhdfs的源代码目录，如：/usr/local/hadoop-2.7.1-src/hadoop-hdfs-project/hadoop-hdfs/src


执行cmake以生成Makefile文件（假设jdk的安装目录为/usr/local/jdk1.7.0_55）：
cmake -DGENERATED_JAVAH=/usr/local/jdk1.7.0_55 -DJAVA_HOME=/usr/local/jdk1.7.0_55 .


成功之后，会在目录下生成Makefile文件，接下来就可以执行make编译生成libhdfs.so和libhdfs.a了。


如果遇到下面这样的错误：
/usr/local/jdk1.7.0_55/jre/lib/amd64/server/libjvm.so: file not recognized: File format not recognized


则需要考虑升级链接器ld，参考说明：http://blog.chinaunix.net/uid-20682147-id-4239779.html。
ld是GNU binutils的成员，可以从下载到新的版本。
注意在升级gcc和ld之后，需要更新下环境变量PATH，再重执行cmake，否则可能引用的仍然是老版本的gcc和ld。


/usr/local/hadoop-2.7.1-src/hadoop-hdfs-project/hadoop-hdfs/src # cmake -DGENERATED_JAVAH=/usr/local/java_1_7 -DJAVA_HOME=/usr/local/java_1_7
-- The C compiler identification is GNU 4.1.2
-- The CXX compiler identification is GNU 4.1.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
JAVA_HOME=/usr/local/java_1_7, JAVA_JVM_LIBRARY=/usr/local/java_1_7/jre/lib/amd64/server/libjvm.so
JAVA_INCLUDE_PATH=/usr/local/java_1_7/include, JAVA_INCLUDE_PATH2=/usr/local/java_1_7/include/linux
Located all JNI components successfully.
-- Performing Test HAVE_BETTER_TLS
-- Performing Test HAVE_BETTER_TLS - Success
-- Performing Test HAVE_INTEL_SSE_INTRINSICS
-- Performing Test HAVE_INTEL_SSE_INTRINSICS - Success
-- Looking for dlopen in dl
-- Looking for dlopen in dl - found
-- Found JNI: /usr/local/java_1_7/jre/lib/amd64/libjawt.so  
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.20") 
-- checking for module 'fuse'
--   package 'fuse' not found
-- Failed to find Linux FUSE libraries or include files.  Will not build FUSE client.
-- Configuring done
-- Generating done
-- Build files have been written to: /usr/local/hadoop-2.7.1-src/hadoop-hdfs-project/hadoop-hdfs/src


接下来就可以执行make来编译生成libhdfs.a了。
没有提供install，需要手工安装头文件hdfs.h和库文件libhdfs.a。


注1：hadoop-2.8.0的编译目录为：
hadoop-2.8.0-src/hadoop-hdfs-project/hadoop-hdfs-native-client/src


注2：如遇到错误“JVM_ARCH_DATA_MODEL is not defined”，解决方法：
cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=/usr/local/hdfs-2.8.0 -DJVM_ARCH_DATA_MODEL=64