我想用java对一个大文件进行字数统计。由于一台机器,我无法使用地图缩减。我想使用Redis来存储单词的频率,而不是使用哈希映射。在实际中,数据是源源不断的。
我以为我会在 redis 排序集中推送每个字数。但我不知道这是不是的最佳解决方案。请提供计算流数据字数的最佳解决方案。
用于字数统计的 Java 代码 -
public class WordCount {
public static void main(String args[]) {
Map<String, Integer> wordMap = wordMap("filename");
List<Entry<String, Integer>> list = sortByValue(wordMap);
for (Map.Entry<String, Integer> entry : list) {
System.out.println(entry.getKey() + " => " + entry.getValue());
}
}
public static Map<String, Integer> wordMap(String fileName) {
Map<String, Integer> wordMap = new HashMap<>();
try (FileInputStream fis = new FileInputStream(fileName);
DataInputStream dis = new DataInputStream(fis);
BufferedReader br = new BufferedReader(new InputStreamReader(dis))) {
// words are separated by whitespace
Pattern pattern = Pattern.compile("\s+");
String line = null;
while ((line = br.readLine()) != null) {
line = line.toLowerCase();
String[] words = pattern.split(line);
for (String word : words) {
if (wordMap.containsKey(word)) {
wordMap.put(word, (wordMap.get(word) + 1));
} else {
wordMap.put(word, 1);
}
}
}
} catch (IOException ioex) {
ioex.printStackTrace();
}
return wordMap;
}
public static List<Entry<String, Integer>> sortByValue(Map<String, Integer> wordMap) {
Set<Entry<String, Integer>> entries = wordMap.entrySet();
List<Entry<String, Integer>> list = new ArrayList<>(entries);
Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
@Override
public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2)
{
return (o2.getValue()).compareTo(o1.getValue());
}
});
return list;
}
}
有一个
很好的例子,说明如何使用Redisson在Java上执行Map Reduce在Redis数据上。