Java执行hadoop的基本操作实例代码

Java执行hadoop的基本操作实例代码

java执行hadoop的基本操作实例代码

向HDFS上传本地文件

public static void uploadInputFile(String localFile) throws IOException{

Configuration conf = new Configuration();

String hdfsPath = "hdfs://localhost:9000/";

String hdfsInput = "hdfs://localhost:9000/user/hadoop/input";

FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);

fs.copyFromLocalFile(new Path(localFile), new Path(hdfsInput));

fs.close();

System.out.println("已经上传文件到input文件夹啦");

}

将output文件下载到本地

public static void getOutput(StrinGmUUkZtKkg outputfile) throws IOException{

String remoteFile = "hdfs://localhost:9000/user/hadoop/output/part-r-00000";

Path path = new Path(remoteFile);

Configuration conf = new Configuration();

String hdfsPath = "hdfs://localhost:9000/";

FileSystem fs = FileSystem.get(URI.create(hdfsPath),conf);

fs.copyToLocalFile(path, new Path(outputfile));

System.out.println("已经将输出文件保留到本地文件");

fs.close();

}

删除hdfs中的文件

public static void deleteOutput() throws IOException{GmUUkZtKk

Configuration conf = new Configuration();

String hdfsOutput = "hdfs://localhost:9000/user/hadoop/output";

String hdfsPath = "hdfs://localhost:9000/";

Path path = new Path(hdfsOutput);

FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);

fs.deleteOnExit(path);

fs.close();

System.out.println("output文件已经删除");

}

执行mapReduce程序

创建Mapper类和Reducer类

public static class TokenizerMapper extends Mapper

private final static IntWritable one = new IntWritable(1);

private Text word = new Text();

public void map(Object key, Text value, Context context) throws IOException, InterruptedException{

String line = value.toString();

line = line.replace("\\", "");

String regex = "性别：(.*?)";

Pattern pattern = Pattern.compile(regex);

Matcher matcher = pattern.matcher(line);

while(matcher.find()){

String term = matcher.group(1);

word.set(term);

context.write(word, one);

}

}

}

public static class IntSumReducer extends Reducer{

private IntWritable result = new IntWritable();

public void reduce(Text key, Iterable values, Context context) throws IOException, InterruptedException{

int sum = 0;

for(IntWritable val :values){

sum+= val.get();

}

result.set(sum);

context.write(key, result);

}

}

执行mapReduce程序

public static void runMapReduce(String[] args) throws Exception {

Configuration conf = new Configuration();

String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();

if(otherArgs.length != 2){

System.err.println("Usage: wordcount ");

System.exit(2);

}

Job job = new Job(conf, "word count");

job.setJarByClass(WordCount.class);

job.setMapperClass(TokenizerMapper.class);

job.setCombinerClass(IntSumReducer.class);

job.setReducerClass(IntSumReducer.class);

job.setOutputKeyClass(Text.class);

job.setOutputValueClass(IntWritable.class);

FileInputFormat.addInputPath(job, new Path(otherArgs[0]));

FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));

System.out.println("mapReduce 执行完毕！");

System.exit(job.waitForCompletion(true)?0:1);

}

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