第二次调用 Hadoop Java API

环境：Hadoop1.2.

例1：读取一个大约200k大小的本地文件，并将其第101-120字节的内容写入HDFS成为一个新文

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.util.Progressable;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;

public class InputTest {
    public static void main(String[] args) throws Exception {
        String localSrc = args[0];
        String dst = args[1];
        InputStream in = new BufferedInputStream(new FileInputStream(localSrc));
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(URI.create(dst), conf);
        OutputStream out = fs.create(new Path(dst), new Progressable() {
            public void progress() {
                System.out.print(".");
            }
        });
        in.read(new byte[100], 0, 100);
        IOUtils.copyBytes(in, out, 20, 20, true);
    }
}

例2. 读取HDSF中的一个约200k大小的文件，并将其第101-120字节的内容写入本地文件系统

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

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;

public class OutputTest {
    public static void main(String[] args) {
        try {
            String dst = args[0];
            String localSrc = args[1];
            File localFile = new File(localSrc);
            if (!localFile.exists()) {
                localFile.mkdirs();
            }

            Configuration conf = new Configuration();
            FileSystem fs = FileSystem.get(URI.create(dst), conf);
            InputStream in = fs.open(new Path(dst));
            OutputStream out = new BufferedOutputStream(new FileOutputStream(localFile));
            in.read(new byte[100], 0, 100);
            IOUtils.copyBytes(in, out, 20, 20, true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}