常见数据类型-HadoopDataType（仅仅作为记录）

package mapred;

import org.apache.hadoop.io.ArrayWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;

/** hadoop数据类型与java数据类型 */
public class HadoopDataType {
    /** 使用hadoop的Text类型数据 */
    public static void testText() {
        System.out.println("testText");
        Text text = new Text("hello hadoop!");
        System.out.println(text.getLength());
        System.out.println(text.find("a"));
        System.out.println(text.toString());
    }

    /** 使用ArrayWritable */
    public static void testArrayWritable() {
        System.out.println("testArrayWritable");
        ArrayWritable arr = new ArrayWritable(IntWritable.class);
        IntWritable year = new IntWritable(2017);
        IntWritable month = new IntWritable(07);
        IntWritable date = new IntWritable(01);
        arr.set(new IntWritable[] { year, month, date });
        System.out.println(String.format("year=%d,month=%d,date=%d",
                ((IntWritable) arr.get()[0]).get(),
                ((IntWritable) arr.get()[1]).get(),
                ((IntWritable) arr.get()[2]).get()));
    }

    /** 使用MapWritable */
    public static void testMapWritable() {
        System.out.println("testMapWritable");
        MapWritable map = new MapWritable();
        Text k1 = new Text("name");
        Text v1 = new Text("tonny");
        Text k2 = new Text("password");
        map.put(k1, v1);
        map.put(k2, NullWritable.get());
        System.out.println(map.get(k1).toString());
        System.out.println(map.get(k2).toString());
    }

    // 入口 main
    public static void main(String[] args) {
        testText();
        testArrayWritable();
        testMapWritable();
    }
}

13
7
hello hadoop!
testArrayWritable
year=2017,month=7,date=1
testMapWritable
tonny
(null)