第2课书面作业

1 在Hadoop集群中编译并运行《权威指南》中的例3.2
2 自行在本地文件系统生成一个大约一百多字节的文本文件，写一段程序（可以利用Java API或C API），读入这个文件，并将其第101-120字节的内容写入HDFS成为一个新文件，提供代码和执行结果演示抓图
3 2的反向操作，在HDFS中生成一个大约一百多字节的文本文件，写一段程序（可以利用Java API或C API），读入这个文件，并将其第101-120字节的内容写入本地文件系统成为一个新文件，提供代码和执行结果演示抓图

1

hadoop.png 运行结果.png

2
package com.keon.hadoop;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
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.*;
import java.net.URI;

/**

• Created by keon on 16/8/14.
  */

public class Exercise2 {

static String PATH = "/exercise2_2";
static String PATH_NEW = "/exercise2_2_1";

public static void main(String[] args) throws IOException {
    Configuration conf = new Configuration();

    FileSystem fs = FileSystem.get(URI.create(PATH), conf);

    FSDataInputStream in = fs.open(new Path(PATH));

    System.out.println("读取全部");
    IOUtils.copyBytes(in, System.out, 4096, false);

    byte[] buffer = new byte[20];
    in.read(101, buffer, 0, 20);

    System.out.println("读取101-120,结果");
    System.out.println(new String(buffer));

    in.close();

    InputStream in2 = new ByteArrayInputStream(buffer);
    FileSystem fs2 = FileSystem.get(URI.create(PATH_NEW), conf);
    OutputStream out2 = fs2.create(new Path(PATH_NEW), new Progressable() {
        @Override
        public void progress() {
            System.out.print("...");
        }
    });

    System.out.print("读取写入:");
    IOUtils.copyBytes(in2, out2, 4096, true);
}

}

运行结果.png hadoop.png

3
package com.keon.hadoop;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
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.*;
import java.net.URI;

/**

• Created by keon on 16/8/14.
  */

public class Exercise3 {

static String PATH = "/exercise2_3";
static String PATH_NEW = "output/exercise2_3_1";

static String content = "别让生活的压力挤走快乐：不管昨天发生了什么，不管昨天的自己有多难堪，有多无奈，有多苦涩，都过去了，不会再来，也无法更改。就让昨天把所有的苦、所有的累、所有的痛远远地带走吧，而今天，我要收拾心情，重新上路！";

public static void main(String[] args) throws IOException {
    Configuration conf = new Configuration();

    InputStream in = new ByteArrayInputStream(content.getBytes());
    FileSystem fs = FileSystem.get(URI.create(PATH), conf);
    OutputStream out = fs.create(new Path(PATH), new Progressable() {
        @Override
        public void progress() {
            System.out.print("...");
        }
    });
    System.out.print("写入中:");
    IOUtils.copyBytes(in, out, 4096, true);
    System.out.println("");

    FSDataInputStream in2 = fs.open(new Path(PATH));

    System.out.println("读取全部");
    IOUtils.copyBytes(in2, System.out, 4096, false);

    byte[] buffer = new byte[20];
    in2.read(101, buffer, 0, 20);
    in2.close();

    System.out.println("读取101-120,结果");
    System.out.println(new String(buffer));

    File file = new File(PATH_NEW);
    if (!file.exists()) {
        file.createNewFile();
    }
    FileOutputStream fop = new FileOutputStream(file);
    fop.write(buffer);
    fop.flush();
    fop.close();
}

}

运行结果.png hadoop.png