ForkJoin统计文件夹中包含关键词的数量

2018-06-09总结:

ForkJoin确实可以很快速的去解析文件并统计关键词的数量,但是如果文件过大就会出现内存溢出,是否可以通过虚拟内存方式解决内存溢出的问题呢?

package com.oxygen.forkjoin.model;

import java.util.List;
/**
 * 文档
 * @author renguanyu
 *
 */
public class Document {

    private List<String> lines;

    public Document(List<String> lines) {
        super();
        this.lines = lines;
    }

    public List<String> getLines() {
        return lines;
    }

    public void setLines(List<String> lines) {
        this.lines = lines;
    }

}

package com.oxygen.forkjoin.model;

import java.util.List;
/**
 * 文件夹
 * @author renguanyu
 *
 */
public class Folder {

    private List<Folder> subFolders;
    private List<Document> documents;

    public Folder(List<Folder> subFolders, List<Document> documents) {
        this.subFolders = subFolders;
        this.documents = documents;
    }

    public List<Folder> getSubFolders() {
        return subFolders;
    }

    public void setSubFolders(List<Folder> subFolders) {
        this.subFolders = subFolders;
    }

    public List<Document> getDocuments() {
        return documents;
    }

    public void setDocuments(List<Document> documents) {
        this.documents = documents;
    }

}

package com.oxygen.forkjoin.service;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import com.oxygen.forkjoin.model.Document;
/**
 * 文档服务
 * @author renguanyu
 *
 */
public class DocumentService {

    /**
     * 读取文件中所以数据
     * @param file 文件
     * @return 文档
     */
    public static Document fromFile(File file) {
        List<String> lines = new ArrayList<>();
        try(BufferedReader reader = new BufferedReader(new FileReader(file))) {
            String line = reader.readLine();
            while (line != null) {
                lines.add(line);
                line = reader.readLine();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return new Document(lines);
    }

}

package com.oxygen.forkjoin.service;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ForkJoinPool;

import com.oxygen.forkjoin.model.Document;
import com.oxygen.forkjoin.model.Folder;
import com.oxygen.forkjoin.task.FolderSearchTask;
/**
 * 文件夹服务
 * @author renguanyu
 *
 */
public class FolderService{

    /**
     * 递归查询文件夹中所有的数据
     * 1.在内存中建立文件夹的结构
     * 2.把数据都加载到这个结构中,方便下一步计算
     * @param dir 文件夹
     * @return 文件夹
     */
    public static Folder fromDirectory(File dir) {
        List<Document> documents = new ArrayList<>();
        List<Folder> subFolders = new ArrayList<>();
        for (File entry : dir.listFiles()) {
            if (entry.isDirectory()) {
                subFolders.add(FolderService.fromDirectory(entry));
            } else {
                documents.add(DocumentService.fromFile(entry));
            }
        }
        return new Folder(subFolders, documents);
    }

    /**
     * 获取关键词总数
     * @param targetFolder 目标文件夹
     * @param keyword 关键词
     * @throws IOException
     */
    public static long getKeywordTotal(String targetFolder, String keyword) {
        ForkJoinPool forkJoinPool = new ForkJoinPool();
        //把文件夹中的数据加载到内存中,我这个文件夹中就一个日志文件
        File dir = new File(targetFolder);
        Folder folder = FolderService.fromDirectory(dir);
        //创建一个搜索任务
        FolderSearchTask task = new FolderSearchTask(folder, keyword);
        //开始执行fork/join任务
        long counts = forkJoinPool.invoke(task);
        return counts;
    }

}

package com.oxygen.forkjoin.task;
import java.util.List;
import java.util.concurrent.RecursiveTask;

import com.oxygen.forkjoin.model.Document;
/**
 * 文档搜索任务
 * @author renguanyu
 *
 */
public class DocumentSearchTask extends RecursiveTask<Long> {

    private static final long serialVersionUID = 1L;

    private Document document;
    private String searchedWord;

    public DocumentSearchTask(Document document, String searchedWord) {
        super();
        this.document = document;
        this.searchedWord = searchedWord;
    }

    @Override
    protected Long compute() {
        long count = 0;
        List<String> lines = document.getLines();
        for (String line : lines) {
            String[] words = line.trim().split("(\\s|\\p{Punct})+");
            for (String word : words) {
                if (searchedWord.equals(word)) {
                    count = count + 1;
                }
            }
        }
        return count;
    }

}

package com.oxygen.forkjoin.task;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.RecursiveTask;

import com.oxygen.forkjoin.model.Document;
import com.oxygen.forkjoin.model.Folder;
/**
 * 文件夹搜索任务
 * @author renguanyu
 *
 */
public class FolderSearchTask extends RecursiveTask<Long> {

    private static final long serialVersionUID = 1L;

    private Folder folder;
    private String searchedWord;

    public FolderSearchTask(Folder folder, String searchedWord) {
        super();
        this.folder = folder;
        this.searchedWord = searchedWord;
    }
    //计算方法
    @Override
    protected Long compute() {
        long count = 0L;
        List<RecursiveTask<Long>> forks = new ArrayList<>();
        //获取文件夹下的子文件夹
        for (Folder subFolder : folder.getSubFolders()) {
            //递归文件夹搜索任务
            FolderSearchTask task = new FolderSearchTask(subFolder, searchedWord);
            //把任务添加到分叉列表,用于合并任务
            forks.add(task);
            //放到工作队列中
            task.fork();
        }
        //获取文件夹下的文档
        for (Document document : folder.getDocuments()) {

            DocumentSearchTask task = new DocumentSearchTask(document, searchedWord);
            //把任务添加到分叉列表,用于合并任务
            forks.add(task);
            //放到工作队列中
            task.fork();
        }
        //合并工作队列中各个线程计算结果的值
        for (RecursiveTask<Long> task : forks) {
            count = count + task.join();
        }
        return count;
    }
}

package com.oxygen.forkjoin.test;

import java.io.IOException;
import com.oxygen.forkjoin.service.FolderService;
/**
 * 测试程序
 * @author renguanyu
 *
 */
public class MainTest {

    public static void main(String[] args) throws IOException {

        long startTime = System.currentTimeMillis();

        long counts = FolderService.getKeywordTotal("C:\\test\\logs\\", "null");

        long stopTime = System.currentTimeMillis();

        long completeTime = stopTime - startTime;

        System.out.println(counts + " , fork / join search took " + completeTime + "ms");
    }
}

原文地址：https://www.cnblogs.com/q651231292/p/9158915.html