引用自:http://blog.csdn.net/johnnywww/article/details/7530364
现在计划做通过C访问Hadoop,选择了LibHDFS,打算用Eclipse(V3.7.2) CDT和cygwin测试。
1.下载CDT,通过Eclipse Install New Software,在地址安装。
2.Cygwin安装开发库,包含gcc, gcc-core,gcc-g++, gcc-mingw-core, gcc-mingw-g++, make , gdb, binutils
3.添加cygwin的bin目录到Windows的Path环境变量里
4.在Windows下执行gcc,运行报错,显示“访问被拒绝” (access denied),检查g++.exe, gcc.exe是否只有1k大小,如果是,那么文件是符号链接,那么把文件重命名一下(备份)。然后把g++-3.exe(或者g++-4.exe)拷贝一份,重命名为g++.exe。 把gcc-3.exe拷贝一份,重命名为gcc.exe,参加文章。
5.编写代码
- #include "hdfs.h"
- int main(int argc, char **argv) {
- if (argc != 4) {
- fprintf(stderr, "Usage: hdfs_write \n");
- exit(-1);
- }
- hdfsFS fs = hdfsConnect("default", 0);
- if (!fs) {
- fprintf(stderr, "Oops! Failed to connect to hdfs!\n");
- exit(-1);
- }
- const char* writeFileName = argv[1];
- tSize fileTotalSize = strtoul(argv[2], NULL, 10);
- tSize bufferSize = strtoul(argv[3], NULL, 10);
- hdfsFile writeFile = hdfsOpenFile(fs, writeFileName, O_WRONLY, bufferSize,
- 0, 0);
- if (!writeFile) {
- fprintf(stderr, "Failed to open %s for writing!\n", writeFileName);
- exit(-2);
- }
- // data to be written to the file
- char* buffer = malloc(sizeof(char) * bufferSize);
- if (buffer == NULL) {
- return -2;
- }
- int i = 0;
- for (i = 0; i < bufferSize; ++i) {
- buffer[i] = 'a' + (i % 26);
- }
- // write to the file
- tSize nrRemaining;
- for (nrRemaining = fileTotalSize; nrRemaining > 0; nrRemaining -=
- bufferSize) {
- int curSize =
- (bufferSize < nrRemaining) ? bufferSize : (int) nrRemaining;
- hdfsWrite(fs, writeFile, (void*) buffer, curSize);
- }
- free(buffer);
- hdfsCloseFile(fs, writeFile);
- hdfsDisconnect (fs);
- return 0;
- }
6.增加环境变量HADOOP_HOME,在cygwin目录下执行
- export HADOOP_HOME=/home/test/hadoop0.20.2
或在/etc/profile文件中增加上述内容。
7.在cygwin里面执行
- gcc writeHDFS.c -I ${HADOOP_HOME}/src/c++/libhdfs -I /usr/local/jdk/include -I/usr/local/jdk/include/win32 -L${HADOOP_HOME}/c++/Linux-i386-32/lib -lhdfs -o writeHDFS
8.在linux里面执行
- gcc writeHDFS.c -I ${HADOOP_HOME}/src/c++/libhdfs -I ${JAVA_HOME}/include -I ${JAVA_HOME}/include/linux -L${HADOOP_HOME}/c++/Linux-i386-32/lib -lhdfs -L${JAVA_HOME}/jre/lib/i386/client -ljvm -o writeHDFS
9.运行./writeHDFS老报错,提示error
while loading shared libraries: libhdfs.so.0: cannot open shared object
file: No such file or
directory,由于hadoop的c++/Linux-i386-32/lib目录下libhdfs.so、libhdfs.so.0、
libhdfs.so.0.0.0文件相同,先将libhdfs.so.0改为libhdfs.so.0.bak,再执行
- ln -s ./libhdfs.so.0.0.0 ./libhdfs.so.0
然后运行
- sudo vi /etc/ld.so.conf
添加如下内容
- /home/pc01/hadoop-1.0.1/c++/Linux-i386-32/lib
- /usr/local/lib/jdk1.7.0_03/jre/lib/i386/server
再运行
- sudo /sbin/ldconfig -v