MapReduce对输入多文件的处理

时间：2021-01-12 18:21:54

 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
}
}



 

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