1.建立测试程序 WordCount.java
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import java.io.IOException;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import java.util.StringTokenizer;
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import org.apache.hadoop.conf.Configuration;
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import org.apache.hadoop.conf.Configured;
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import org.apache.hadoop.fs.Path;
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import org.apache.hadoop.io.IntWritable;
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import org.apache.hadoop.io.LongWritable;
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import org.apache.hadoop.io.Text;
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import org.apache.hadoop.mapred.FileInputFormat;
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import org.apache.hadoop.mapred.FileOutputFormat;
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import org.apache.hadoop.mapred.JobClient;
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import org.apache.hadoop.mapred.JobConf;
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import org.apache.hadoop.mapred.MapReduceBase;
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import org.apache.hadoop.mapred.Mapper;
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import org.apache.hadoop.mapred.OutputCollector;
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import org.apache.hadoop.mapred.Reducer;
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import org.apache.hadoop.mapred.Reporter;
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import org.apache.hadoop.util.Tool;
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import org.apache.hadoop.util.ToolRunner;
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public class WordCount extends Configured implements Tool {
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public static class MapClass extends MapReduceBase implements
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Mapper<LongWritable, Text, Text, IntWritable> {
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private final static IntWritable one = new IntWritable(1);
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private Text word = new Text();
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public void map(LongWritable key, Text value,
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OutputCollector<Text, IntWritable> output, Reporter reporter)
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throws IOException {
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String line = value.toString();
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StringTokenizer itr = new StringTokenizer(line);
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while (itr.hasMoreTokens()) {
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word.set(itr.nextToken());
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output.collect(word, one);
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}
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}
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}
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/**
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* A reducer class that just emits the sum of the input values.
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*/
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public static class Reduce extends MapReduceBase implements
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Reducer<Text, IntWritable, Text, IntWritable> {
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public void reduce(Text key, Iterator<IntWritable> values,
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OutputCollector<Text, IntWritable> output, Reporter reporter)
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throws IOException {
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int sum = 0;
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while (values.hasNext()) {
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sum += values.next().get();
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}
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output.collect(key, new IntWritable(sum));
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}
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}
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static int printUsage() {
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System.out.println("wordcount [-m ] [-r ] );
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ToolRunner.printGenericCommandUsage(System.out);
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return -1;
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}
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/**
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* The main driver for word count map/reduce program. Invoke this method to
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* submit the map/reduce job.
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*
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* @throws IOException
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* When there is communication problems with the job tracker.
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*/
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public int run(String[] args) throws Exception {
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JobConf conf = new JobConf(getConf(), WordCount.class);
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conf.setJobName("wordcount");
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// the keys are words (strings)
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conf.setOutputKeyClass(Text.class);
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// the values are counts (ints)
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conf.setOutputValueClass(IntWritable.class);
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conf.setMapperClass(MapClass.class);
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conf.setCombinerClass(Reduce.class);
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conf.setReducerClass(Reduce.class);
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List<String> other_args = new ArrayList<String>();
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for (int i = 0; i < args.length; ++i) {
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try {
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if ("-m".equals(args[i])) {
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conf.setNumMapTasks(Integer.parseInt(args[++i]));
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} else if ("-r".equals(args[i])) {
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conf.setNumReduceTasks(Integer.parseInt(args[++i]));
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} else {
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other_args.add(args[i]);
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}
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} catch (NumberFormatException except) {
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System.out.println("ERROR: Integer expected instead of "
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+ args[i]);
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return printUsage();
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} catch (ArrayIndexOutOfBoundsException except) {
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System.out.println("ERROR: Required parameter missing from "
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+ args[i - 1]);
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return printUsage();
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}
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}
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// Make sure there are exactly 2 parameters left.
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if (other_args.size() != 2) {
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System.out.println("ERROR: Wrong number of parameters: "
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+ other_args.size() + " instead of 2.");
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return printUsage();
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}
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FileInputFormat.setInputPaths(conf, other_args.get(0));
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FileOutputFormat.setOutputPath(conf, new Path(other_args.get(1)));
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JobClient.runJob(conf);
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return 0;
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}
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public static void main(String[] args) throws Exception {
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int res = ToolRunner.run(new Configuration(), new WordCount(), args);
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System.exit(res);
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}
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}
编译上述程序,利用下述命令将编译所得的class文件打包成jar包
$ bin/hadoop fs -cat /tmp/output/part-00000
jar cvf WordCount.jar *.class
接下来的操作和运行源码包中例子一样。就不多说了。
转载地址:http://blog.csdn.net/aspirinxp/article/details/6590468
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