hadoop hdfs 文件系统操作

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import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.io.IOUtils;
import org.junit.Test;

import java.io.FileOutputStream;
import java.io.IOException;

/**
 * 2018-7-15
 * 对hdfs文件系统的增删改查
 * 底层是数据的操作
 */
public class MyHDFSBaseHandle {
    @Test
    // 读数据
    public void test() throws IOException {
        Configuration conf = new Configuration();

        //代码入口点，初始化hdfs文件系统
        FileSystem fs = FileSystem.get(conf);

        //通过fs读数据
        Path p = new Path("/test.txt");
        FSDataInputStream fis = fs.open(p);

        int len = 0;
        byte[] buff = new byte[1024];
        while((len = fis.read(buff)) != -1) {
            System.out.println(new String(buff,0,len));
        }
    }

    @Test
    //出现 winutil问题
    // 写入文件
    public void test2() throws Exception{
        System.setProperty("HADOOP_USER_NAME", "centos");
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        Path p = new Path("/t3.txt");
        FSDataOutputStream out = fs.create(p);
        out.write("the people's republic of china".getBytes());
        out.flush();
        out.close();
    }

    @Test
    // 文件的追加
    public void test3() throws Exception{
        System.setProperty("HADOOP_USER_NAME", "centos");
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        Path p = new Path("/t3.txt");
        FSDataOutputStream append = fs.append(p);
        append.write("i love this computer! it's has big power.".getBytes());
        append.flush();
        append.close();
    }

    @Test
    // 删除文件
    public void test4() throws Exception {
        System.setProperty("HADOOP_USER_NAME", "centos");
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        Path p = new Path("/t3.txt");
        fs.delete(p, true);
        fs.close();
    }

    @Test
    // 把hdfs内的文件复制到本地
    public void test5() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        Path p = new Path("/aa/t2.txt");
        FSDataInputStream in = fs.open(p);

        FileOutputStream out = new FileOutputStream("tt.txt");
        IOUtils.copyBytes(in, out, 1024);
        in.close();
        out.close();
        fs.close();
    }

    @Test
    /**
     * 列出文件信息
     */
    public void test6() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        FileStatus[] status = fs.listStatus(new Path("/"));
        for(FileStatus satus1 : status) {
            System.out.println(satus1.getPath());
        }
        fs.close();
    }


}