MapReduce对输入多文件的处理

MultipleInputs类指定不同的输入文件路径以及输入文化格式

现有两份数据

phone

123,good number

124,common number

125,bad number

user

zhangsan,123

lisi,124

wangwu,125

现在需要把user和phone按照phone number连接起来。得到下面的结果

zhangsan,123,good number

lisi,123,common number

wangwu,125,bad number

分析思路

还是相当于两张表的一对一join操作。join时对value设置个Bean(JavaBean实现writablecomparable接口)，key为外键值

join的优化,详见http://blog.csdn.net/u010366796/article/details/44649933，设置KeyBean(外健和标识flag属性)，进行排序

本例中将通过value进行排序，即在value的JavaBean中通过实习CompareTo()方法，完成排序，使得phone表位于首位

1.对value实现JavaBean(实现writablecomparable接口)

package test.mr.multiinputs;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.io.WritableComparable;

/*
 * 自定义的JavaBean
 */
public class FlagString implements WritableComparable<FlagString> {
	private String value;
	private int flag; // 标记 0:表示phone表 1：表示user表

	public FlagString() {
		super();
		// TODO Auto-generated constructor stub
	}

	public FlagString(String value, int flag) {
		super();
		this.value = value;
		this.flag = flag;
	}

	public String getValue() {
		return value;
	}

	public void setValue(String value) {
		this.value = value;
	}

	public int getFlag() {
		return flag;
	}

	public void setFlag(int flag) {
		this.flag = flag;
	}

	@Override
	public void write(DataOutput out) throws IOException {
		out.writeInt(flag);
		out.writeUTF(value);

	}

	@Override
	public void readFields(DataInput in) throws IOException {
		this.flag = in.readInt();
		this.value = in.readUTF();
	}

	@Override
	public int compareTo(FlagString o) {
		if (this.flag >= o.getFlag()) {
			if (this.flag > o.getFlag()) {
				return 1;
			}
		} else {
			return -1;
		}
		return this.value.compareTo(o.getValue());
	}

}

2.多map类，map1(实现对phone表文件操作)

package test.mr.multiinputs;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class MultiMap1 extends Mapper<LongWritable, Text, Text, FlagString> {
	private String delimiter; // 定义分隔符,由job端设置

	@Override
	protected void setup(
			Mapper<LongWritable, Text, Text, FlagString>.Context context)
			throws IOException, InterruptedException {
		delimiter = context.getConfiguration().get("delimiter", ",");
	}

	@Override
	protected void map(LongWritable key, Text value,
			Mapper<LongWritable, Text, Text, FlagString>.Context context)
			throws IOException, InterruptedException {
		String line = value.toString().trim();
		if (line.length() > 0) {
			String[] str = line.split(delimiter);
			if (str.length == 2) {
				context.write(new Text(str[0].trim()),
						new FlagString(str[1].trim(), 0)); // flag=0,表示phone表
			}
		}
	}
}

2.map2(实现对user表文件操作)

package test.mr.multiinputs;

import java.io.IOException;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class MultiMap2 extends Mapper<LongWritable, Text, Text, FlagString> {
	private String delimiter; // 设置分隔符

	@Override
	protected void setup(
			Mapper<LongWritable, Text, Text, FlagString>.Context context)
			throws IOException, InterruptedException {
		delimiter = context.getConfiguration().get("delimiter", ",");
	}

	@Override
	protected void map(LongWritable key, Text value,
			Mapper<LongWritable, Text, Text, FlagString>.Context context)
			throws IOException, InterruptedException {
		String line = value.toString().trim();
		if (line.length() > 0) {
			String[] str = line.split(delimiter);
			if (str.length == 2) {
				context.write(new Text(str[1].trim()),
						new FlagString(str[0].trim(), 1)); // flag=1为user表
			}
		}
	}
}

3.reduce类

package test.mr.multiinputs;

import java.io.IOException;

import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class MultiRedu extends Reducer<Text, FlagString, NullWritable, Text> {
	private String delimiter; // 设置分隔符

	@Override
	protected void setup(
			Reducer<Text, FlagString, NullWritable, Text>.Context context)
			throws IOException, InterruptedException {
		delimiter = context.getConfiguration().get("delimiter", ",");
	}

	@Override
	protected void reduce(Text key, Iterable<FlagString> values,
			Reducer<Text, FlagString, NullWritable, Text>.Context context)
			throws IOException, InterruptedException {
		// 最后输出的格式为: uservalue,key,phonevalue
		String phoneValue = "";
		String userValue = "";
		int num = 0;
		for (FlagString value : values) {
			// 第一个即为phone表
			if (num == 0) {
				phoneValue = value.getValue();
				num++;
			} else {
				userValue = value.getValue();
				context.write(NullWritable.get(),
						new Text(userValue + key.toString() + phoneValue));
			}
		}
	}
}

4.job类(关键!!实现多文件的输入格式等)

package test.mr.multiinputs;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.MultipleInputs;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

/*
 * MultipleInputs类指定不同的输入文件路径以及输入文化格式
 现有两份数据
 phone
 123,good number
 124,common number
 123,bad number

 user
 zhangsan,123
 lisi,124
 wangwu,125

 现在需要把user和phone按照phone number连接起来。得到下面的结果
 zhangsan,123,good number
 lisi,123,common number
 wangwu,125,bad number
 */
public class MultiMapMain extends Configuration implements Tool {
	private String input1 = null; // 定义的多个输入文件
	private String input2 = null;
	private String output = null;
	private String delimiter = null;

	@Override
	public void setConf(Configuration conf) {

	}

	@Override
	public Configuration getConf() {
		return new Configuration();
	}

	@Override
	public int run(String[] args) throws Exception {
		setArgs(args);
		checkParam();// 对参数进行检测

		Configuration conf = new Configuration();
		Job job = new Job(conf);
		job.setJarByClass(MultiMapMain.class);

		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(FlagString.class);

		job.setReducerClass(MultiRedu.class);
		job.setOutputKeyClass(NullWritable.class);
		job.setOutputValueClass(Text.class);

		// MultipleInputs类添加文件路径
		MultipleInputs.addInputPath(job, new Path(input1),
				TextInputFormat.class, MultiMap1.class);
		MultipleInputs.addInputPath(job, new Path(input2),
				TextInputFormat.class, MultiMap2.class);

		FileOutputFormat.setOutputPath(job, new Path(output));
		job.waitForCompletion(true);
		return 0;
	}

	private void checkParam() {
		if (input1 == null || "".equals(input1.trim())) {
			System.out.println("no input phone-data path");
			userMaunel();
			System.exit(-1);
		}
		if (input2 == null || "".equals(input2.trim())) {
			System.out.println("no input user-data path");
			userMaunel();
			System.exit(-1);
		}
		if (output == null || "".equals(output.trim())) {
			System.out.println("no output path");
			userMaunel();
			System.exit(-1);
		}
		if (delimiter == null || "".equals(delimiter.trim())) {
			System.out.println("no delimiter");
			userMaunel();
			System.exit(-1);
		}

	}

	// 用户手册
	private void userMaunel() {
		System.err.println("Usage:");
		System.err.println("-i1 input \t phone data path.");
		System.err.println("-i2 input \t user data path.");
		System.err.println("-o output \t output data path.");
		System.err.println("-delimiter data delimiter \t default comma.");
	}

	// 对属性进行赋值
	// 设置输入的格式:-i1 xxx(输入目录) -i2 xxx(输入目录) -o xxx(输出目录) -delimiter x(分隔符)
	private void setArgs(String[] args) {
		for (int i = 0; i < args.length; i++) {
			if ("-i1".equals(args[i])) {
				input1 = args[++i]; // 将input1赋值为第一个文件的输入路径
			} else if ("-i2".equals(args[i])) {
				input2 = args[++i];
			} else if ("-o".equals(args[i])) {
				output = args[++i];
			} else if ("-delimiter".equals(args[i])) {
				delimiter = args[++i];
			}
		}
	}

	public static void main(String[] args) throws Exception {
		Configuration conf = new Configuration();
		ToolRunner.run(conf, new MultiMapMain(), args); // 调用run方法
	}
}