hadoop上运行java程序
1，分词统计
import java.io.IOException;import java.util.Iterator;import java.util.StringTokenizer;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.LongWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapred.FileInputFormat;import org.apache.hadoop.mapred.FileOutputFormat;import org.apache.hadoop.mapred.JobClient;import org.apache.hadoop.mapred.JobConf;import org.apache.hadoop.mapred.MapReduceBase;import org.apache.hadoop.mapred.Mapper;import org.apache.hadoop.mapred.OutputCollector;import org.apache.hadoop.mapred.Reducer;import org.apache.hadoop.mapred.Reporter;import org.apache.hadoop.mapred.TextInputFormat;import org.apache.hadoop.mapred.TextOutputFormat;public class WordCount { public static class Map extends MapReduceBase implements Mapper { private final static IntWritable one = new IntWritable(1); private Text word = new Text(); public void map(LongWritable key, Text value, OutputCollector output, Reporter reporter) throws IOException { String line = value.toString(); StringTokenizer tokenizer = new StringTokenizer(line); while (tokenizer.hasMoreTokens()) { word.set(tokenizer.nextToken()); output.collect(word, one); } } } public static class Reduce extends MapReduceBase implements Reducer { public void reduce(Text key, Iterator values, OutputCollector output, Reporter reporter) throws IOException { int sum = 0; while (values.hasNext()) { sum += values.next().get(); } output.collect(key, new IntWritable(sum)); } } public static void main(String[] args) throws Exception { JobConf conf = new JobConf(WordCount.class); conf.setJobName("wordcount"); conf.setOutputKeyClass(Text.class); conf.setOutputValueClass(IntWritable.class); conf.setMapperClass(Map.class); conf.setCombinerClass(Reduce.class); conf.setReducerClass(Reduce.class); conf.setInputFormat(TextInputFormat.class); conf.setOutputFormat(TextOutputFormat.class); FileInputFormat.setInputPaths(conf, new Path(args[0])); FileOutputFormat.setOutputPath(conf, new Path(args[1])); JobClient.runJob(conf); }}?
Eclipse打包
JAR File->................反正自己会了，忽略掉吧，简单的说
生成JAR文件，上传到/opt/hadoop/下
然后在hdfs上建立一个文件夹，hadoop fs -mkdir /test
hadoop fs -put /root/wordtestnum.txt? /test
然后执行hadoop jar /opt/hadoop/count.jar /test/wordtestnum.txt??? /test/out
查看运行结果hadoop fs -cat /test/out/part-00000
二，统计平均分
import java.io.IOException;import java.util.Iterator;import java.util.StringTokenizer;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.LongWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapred.FileInputFormat;import org.apache.hadoop.mapred.FileOutputFormat;import org.apache.hadoop.mapred.JobClient;import org.apache.hadoop.mapred.JobConf;import org.apache.hadoop.mapred.MapReduceBase;import org.apache.hadoop.mapred.Mapper;import org.apache.hadoop.mapred.OutputCollector;import org.apache.hadoop.mapred.Reducer;import org.apache.hadoop.mapred.Reporter;import org.apache.hadoop.mapred.TextInputFormat;import org.apache.hadoop.mapred.TextOutputFormat;public class StaticScore {public static class Map extends MapReduceBase implementsMapper<LongWritable, Text, Text, IntWritable> {// private Text word = new Text();public void map(LongWritable key, Text value,OutputCollector<Text, IntWritable> output, Reporter reporter)throws IOException {String line = value.toString();StringTokenizer tokenizerArticle = new StringTokenizer(line, "\n");while (tokenizerArticle.hasMoreTokens()) {StringTokenizer tokenizerLine = new StringTokenizer(tokenizerArticle.nextToken());String strName = tokenizerLine.nextToken();String strScore = tokenizerLine.nextToken();Text name = new Text(strName);int scoreInt = Integer.parseInt(strScore);output.collect(name, new IntWritable(scoreInt));}}}public static class Reduce extends MapReduceBase implementsReducer<Text, IntWritable, Text, IntWritable> {public void reduce(Text key, Iterator<IntWritable> values,OutputCollector<Text, IntWritable> output, Reporter reporter)throws IOException {int sum = 0;int count = 0;while (values.hasNext()) {sum += values.next().get();count++;}int average = (int) sum / count;output.collect(key, new IntWritable(average));}}public static void main(String[] args) throws Exception {JobConf conf = new JobConf(StaticScore.class);conf.setJobName("staticscore");conf.setOutputKeyClass(Text.class);conf.setOutputValueClass(IntWritable.class);conf.setMapperClass(Map.class);conf.setCombinerClass(Reduce.class);conf.setReducerClass(Reduce.class);conf.setInputFormat(TextInputFormat.class);conf.setOutputFormat(TextOutputFormat.class);FileInputFormat.setInputPaths(conf, new Path(args[0]));FileOutputFormat.setOutputPath(conf, new Path(args[1]));JobClient.runJob(conf);}}?
TXT文本：
[code="html"]罗玉网? 122
曾子明? 88
欧汉声? 89
汪涵??? 90
曾子明? 78
汪涵??? 89
汪涵??? 99
代码解释详见：https://www.ibm.com/developerworks/cn/opensource/os-cn-hadoop2/
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