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);
    }

}