在通过Hadoop的C的API 访问HDFS的时候，编译和运行出现了不少问题，在这边，做个总结吧：
系统：Ubuntu 11.04，Hadoop-0.20.203.0
样例代码就是参考官方文档中提供到：
#include "hdfs.h" int main(int argc, char **argv) { hdfsFS fs = hdfsConnect("default", 0); const char* writePath = "/tmp/testfile.txt"; hdfsFile writeFile = hdfsOpenFile(fs, writePath, O_WRONLY|O_CREAT, 0, 0, 0); if(!writeFile) { fprintf(stderr, "Failed to open %s for writing!\n", writePath); exit(-1); } char* buffer = "Hello, World!"; tSize num_written_bytes = hdfsWrite(fs, writeFile, (void*)buffer, strlen(buffer)+1); if (hdfsFlush(fs, writeFile)) { fprintf(stderr, "Failed to 'flush' %s\n", writePath); exit(-1); } hdfsCloseFile(fs, writeFile); }编译：官网这样描述
See the Makefile for hdfs_test.c in the libhdfs source directory (${HADOOP_HOME}/src/c++/libhdfs/Makefile) or something like:
gcc above_sample.c -I${HADOOP_HOME}/src/c++/libhdfs -L${HADOOP_HOME}/libhdfs -lhdfs -o above_sample
但是我两个方法都试了，不行，后面发现原来是要少了：
LIB = -L$(HADOOP_INSTALL)/c++/Linux-i386-32/lib/ libjvm=/usr/lib/jvm/java-6-openjdk/jre/lib/i386/client/libjvm.so所以完整到makefile就是：
HADOOP_INSTALL=/home/fzuir/hadoop-0.20.203.0 PLATFORM=Linux-i386-32 JAVA_HOME=/usr/lib/jvm/java-6-openjdk/ CPPFLAGS= -I$(HADOOP_INSTALL)/src/c++/libhdfs LIB = -L$(HADOOP_INSTALL)/c++/Linux-i386-32/lib/ libjvm=/usr/lib/jvm/java-6-openjdk/jre/lib/i386/client/libjvm.so LDFLAGS += -lhdfs testHdfs: testHdfs.c gcc testHdfs.c $(CPPFLAGS) $(LIB) $(LDFLAGS) $(libjvm) -o testHdfs clean: rm testHdfs好了，编译通过，但是运行的时候出现以下错误信息：
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/configuration/Configuration
...
Call to org.apache.hadoop.fs.Filesystem::get(URI, Configuration) failed!
Exception in thread "main" java.lang.NullPointerException
Call to get configuration object from filesystem failed!
解决方法：将HADOOP_HOME和HADOOP_HOME/lib下所有到jar包加入/usr/lib/jvm/java-6-openjdk/jre/lib/ext/（其实只要需要到加入，但是不知道哪些是需要的）
最后，恭喜你，问题解决了。