Hadoop 学习笔记（一） HDFS API

http://www.cnblogs.com/liuling/p/2013-6-17-01.html 这个也不错 http://www.teamwiki.cn/hadoop/thrift      thrift编程

1.上传本地文件到ＨＤＦＳ

package proj;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class CopyFile {
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
//要点：没有这句会传到本地文件系统，而不是hdfs
conf.set("fs.default.name","hdfs://localhost:9000");
FileSystem hdfs = FileSystem.get(conf);
Path src = new Path("/codes/c/hello.c");
Path dst = new Path("in");
hdfs.copyFromLocalFile(src, dst);
System.out.println("Upload to" + conf.get("fs.default.name"));
FileStatus[] files = hdfs.listStatus(dst);
for (FileStatus fileStatus : files) {
System.out.println(fileStatus.getPath());
}
}
}

2.创建HDFS文件
package proj;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class CreateFile {

public static void main(String[] args) throws IOException {
Configuration conf = new Configuration();
//要点：没有这句会传到本地文件系统，而不是hdfs
conf.set("fs.default.name","hdfs://localhost:9000");
FileSystem hdfs = FileSystem.get(conf);
Path dfs = new Path("in/test.txt");
FSDataOutputStream outputStream = hdfs.create(dfs);
byte[] buff = "hello prince of persia".getBytes();
outputStream.write(buff, 0, buff.length);
System.out.println("run over");
}

}

3.重命名
package proj;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class Rename {

public static void main(String[] args) throws IOException {
Configuration conf = new Configuration();
//要点：没有这句会传到本地文件系统，而不是hdfs
conf.set("fs.default.name","hdfs://localhost:9000");
FileSystem hdfs = FileSystem.get(conf);
Path frpath = new Path("in/test.txt");
Path topath = new Path("in/test3.txt");
boolean isRename = hdfs.rename(frpath, topath);
System.out.println(isRename);
}

}