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需求

需求分析

代码实现

public class WordCount {      private static Map
   
     wordFrequencyMap = new HashMap<>();      public static void main(String[] args) throws IOException, InterruptedException, URISyntaxException {          Connection_Texture fs = FileSystem.get("hdfs://hadoop01:9000", new Configuration(), "root");          FSDataInputStream inputStream = fs.open(new Path("/data/ghm.txt"));          BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));          String line = null;          while ((line = reader.readLine()) != null) {              // 按空格或Tab分割单词              String[] words = line.split("\\s+");              for (String word : words) {                  Integer count = wordFrequencyMap.getOrDefault(word, 0);                  if (count >= 0) {                      count++;                      wordFrequencyMap.put(word, count);                  }              }          }          Path outputPath = new Path("/user/hdfs-wordcount/part-r-0001");          FSDataOutputStream outputStream = fs.create(outputPath);          TreeSet
    
     
      > entrySet = wordFrequencyMap.entrySet();          for (Map.Entry
      
        entry : entrySet) {              String entryKey = entry.getKey();              Integer entryValue = entry.getValue();              outputStream.write((entryKey + "=" + entryValue + "\r\n").getBytes());              System.out.println("[INFO] 处理结果：" + entryKey + "=" + entryValue);          }          reader.close();          inputStream.close();          fs.close();      }  }
      
     
    
   

以上代码实现了对指定HDFS文件的单词频率统计，按键值对存储至目标文件中。开发者可通过hdfs dfs -ls /user/hdfs-wordcount等命令验证输出结果。