与HDFS交互- By java API编程

（1）”/usr/local/hadoop/share/hadoop/common”目录下的hadoop-common-2.9.1.jar和haoop-nfs-2.9.1.jar；
（2）“/usr/local/hadoop/share/hadoop/common/lib”目录下的所有JAR包；
（3）“/usr/local/hadoop/share/hadoop/hdfs”目录下的haoop-hdfs-2.9.1.jar和haoop-hdfs-nfs-2.9.1.jar；
（4）“/usr/local/hadoop/share/hadoop/hdfs/lib”目录下的所有JAR包。

//工具类

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.net.URI;

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 Temp {
    public void createFileOnHDFS() {
        String rootPath="hdfs://Kouri:9000/";
        Configuration conf=new Configuration();
        conf.set("fs.defaultFS", "hdfs://Kouri:9000");
        conf.set("fs.hdfs.impl", "org.apache.hadoop.hdfs.DistributedFileSystem");
        try {
            FileSystem fs=FileSystem.get(URI.create(rootPath),conf);
            Path hdfsPath=new Path(rootPath+"/user/hadoop/demo1.txt");
            System.out.println(""+fs.getHomeDirectory());
            String con="hello world";
            FSDataOutputStream fout=fs.create(hdfsPath);
            BufferedOutputStream bout=new BufferedOutputStream(fout);
            bout.write(con.getBytes(),0,con.getBytes().length);
            bout.close();
            fout.close();
            System.out.println(hdfsPath+"创建");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

//测试类

public class Test {
    public static void main(String []args) {
        Temp temp=new Temp();
        temp.createFileOnHDFS();
    }
}