一、创建maven下项目
二、pom引用
<dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-client</artifactId> <version>2.7.1</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>2.7.1</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-hdfs</artifactId> <version>2.7.1</version> </dependency> 三、如图四、本地调式
5、远程调式
示例代码：
package com.hadoop; import org.apache.hadoop.conf.Configuration; 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.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 java.util.Iterator; import java.util.StringTokenizer; import java.io.IOException; /** * Created by jing on 17/6/6. */ public class HdfsUpload { public static void main(String[] args) throws Exception { if (args.length != 2) { System.err.println("参数无效"); System.exit(-1); } Configuration conf = new Configuration(); //主要设置 conf.set("fs.defaultFS","hdfs://192.168.46.225:9000"); Job job = Job.getInstance(); job.setJarByClass(HdfsUpload.class); job.setJobName("HdfsUpload"); FileInputFormat.addInputPath(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); job.setMapperClass(WcMapper.class); job.setReducerClass(WcReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); System.exit(job.waitForCompletion(true) ? 0 : 1); } } class WcReducer extends Reducer<Text, IntWritable, Text, IntWritable> { public void reduce(Text key, Iterable<IntWritable> values, Mapper.Context context) throws IOException, InterruptedException { int sum= 0; Iterator<IntWritable> iterator=values.iterator(); while (iterator.hasNext()){ sum +=iterator.next().get(); } context.write(key,new IntWritable(sum)); } } class WcMapper extends Mapper<LongWritable, Text, Text, IntWritable> { //注1 private static final int MISSING = 9999; private final static IntWritable one =new IntWritable(1); private Text word = new Text(); @Override public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String line= value.toString(); StringTokenizer tokenizer = new StringTokenizer(line); while (tokenizer.hasMoreTokens()){ word.set(tokenizer.nextToken()); context.write(word,one); } } }