hadoop实战多表关联

xiaochuan

　　多表关联处理获取结果，大致意思把数据切割成左右表

package org.apache.hadoop.examples;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
public class STjoin {
public static int time = 0;
public static class Map extends Mapper<Object, Text, Text, Text> {
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String childname = new String();
String parentname = new String();
String type = new String();
String line = value.toString();
int i = 0;
while (line.charAt(i) != ' ') {
i++;
}
String[] values = { line.substring(0, i), line.substring(i + 1) };
if (values[0].compareTo("child") != 0) {
childname = values[0];
parentname = values[1];
type = "1";
context.write(new Text(values[1]), new Text(type + "+"
+ childname + "+" + parentname));
type = "2";
context.write(new Text(values[0]), new Text(type + "+"
+ childname + "+" + parentname));
}
}
}
public static class IntSumReducer extends Reducer<Text, Text, Text, Text> {
public void reduce(Text key, Iterable<IntWritable> values,
Context context) throws IOException, InterruptedException {
if (time == 0) {
context.write(new Text("grandchild"), new Text("grandparent"));
time++;
}
int grandchildnum = 0;
String grandchild[] = new String[10];
int grandparentnum = 0;
String grandparent[] = new String[10];
Iterator ite = values.iterator();
while (ite.hasNext()) {
String record = ite.next().toString();
int len = record.length();
int i = 2;
if (len == 0)
continue;
char type = record.charAt(0);
String childname = new String();
String parentname = new String();
System.out.println("------------------" + record);
while (record.charAt(i) != '+') {
childname = childname + record.charAt(i);
i++;
// System.out.println("childname" + childname);
}
i = i + 1;
while (i < len) {
parentname = parentname + record.charAt(i);
i++;
// System.out.println("parentname" + parentname);
}
if (type == '1') {
grandchild[grandchildnum] = childname;
grandchildnum++;
} else {
grandparent[grandparentnum] = parentname;
grandparentnum++;
}
}
if (grandparentnum != 0 && grandchildnum != 0) {
for (int i = 0; i < grandchildnum; i++) {
for (int j = 0; j < grandparentnum; j++) {
context.write(new Text(grandchild), new Text(
grandparent[j]));
}
}
}
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf, args)
.getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: wordcount <in> <out>");
System.exit(2);
}
Job job = new Job(conf, "stsort");
job.setJarByClass(STjoin.class);
job.setMapperClass(Map.class);
job.setReducerClass(IntSumReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}