Linux下编译java并生成jar包

下面是WordCount.java类

   
   
   

    
    
    
package com.ll;
    
    
    

    
    
    
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<LongWritable, Text, Text, IntWritable> {
    
    
    
 private final static IntWritable one = new IntWritable(1);
    
    
    
 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 tokenizer = new StringTokenizer(line);
    
    
    
 while (tokenizer.hasMoreTokens()) {
    
    
    
 word.set(tokenizer.nextToken());
    
    
    
 output.collect(word, one);
    
    
    
 }
    
    
    
 }
    
    
    
 }
    
    
    

    
    
    
 public static class Reduce extends MapReduceBase implements
    
    
    
 Reducer<Text, IntWritable, Text, IntWritable> {
    
    
    
 public void reduce(Text key, Iterator<IntWritable> values,
    
    
    
 OutputCollector<Text, IntWritable> 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);
    
    
    
 }
    
    
    
}
   
   
   

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使用Linux命令行编译java代码，并生成jar包

   
   
   

    
    
    
mkdir wordcount_classes 
    
    
    
javac -classpath ${HADOOP_HOME}/hadoop-${HADOOP_VERSION}-core.jar -d wordcount_classes/ WordCount.java 
    
    
    
jar -cvf /usr/joe/wordcount121.jar -C wordcount_classes/ .
   
   
   

说明：

• javac ：用于编译java--->class文件；
  
• -classpath：后面指定依赖的jara包存储的位置；
  
• -d：指定输出目录；
  

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