1、讀取檔案

   /**
     * 測試讀取檔案
     * @throws IOException
     */
    @Test
    public void testSave() throws IOException {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        FSDataInputStream fis = fs.open(new Path("hdfs://s150:8020/usr/xiaoqiu/hadoop/mydir1/hello1.txt"));
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        IOUtils.copyBytes(fis,baos,1024);
        fis.close();
        System.out.println(new String(baos.toByteArray()));
    }
 

2、寫入檔案

    /**
     * 測試寫入檔案
     */
    @Test
    public void testWrite () throws IOException {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        FSDataOutputStream fos =  fs.create(new Path("hdfs://s150:8020/usr/xiaoqiu/hadoop/mydir1/hello1.txt"));
        fos.write("hello world".getBytes());
        fos.close();
    }
 

3、定製副本數和blocksize

 /**
     * 定製副本數和blocksize
     */
    @Test
    public void testWrite2 () throws IOException {
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        FSDataOutputStream fos = fs.create(new Path("hdfs://s150:8020/usr/xiaoqiu/hadoop/mydir1/hello1.txt"),
                true,
                1024,
                (short)2,
                1024);
        fos.write("how are you ".getBytes());
        fos.close();

    }
 

[[email protected] /soft/hadoop/etc/hadoop]$ cat hdfs-site.xml
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
  <name>dfs.replication</name>
  <value>2</value>
</property>
<property>
   <name>dfs.namenode.fs-limits.min-block-size</name>
   <value>1024</value>
</property>
</configuration>