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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