利用Callable，统计目录下有多少个文件中包含指定的关键字_matchcounter counter=new matchcounter(file, keywor-优快云博客

本文介绍了一个使用Java编写的程序，该程序能够并发地在指定目录及其子目录中搜索包含特定关键词的所有文件。通过使用FutureTask和Callable接口实现多线程处理，有效地提高了搜索效率。

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import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;

public class FutureTest {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		System.out.print("Enter base directory (C:/Program Files/Java/jdk1.7.0/src):");
		String directory = in.nextLine();
		System.out.print("Enter keyword (java):");
		String keyword = in.nextLine();
		
		MatchCounter counter = new MatchCounter(new File(directory), keyword);
		FutureTask<Integer> task = new FutureTask<Integer>(counter);
		Thread t = new Thread(task);
		t.start();
		
		try {
			System.out.println(task.get() + " matching files.");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

class MatchCounter implements Callable<Integer> {

	public MatchCounter(File directory, String keyword) {
		this.directory = directory;
		this.keyword = keyword;
	}
	
	@Override
	public Integer call() throws Exception {
		count = 0;
		
		try {
			File[] files = directory.listFiles();
			ArrayList<FutureTask<Integer>> results = new ArrayList<FutureTask<Integer>>();
			
			for(File file : files) {
				if(file.isDirectory()) {
					//再为每一个目录在启动一个线程
					MatchCounter counter = new MatchCounter(file, keyword);
					FutureTask<Integer> task = new FutureTask<Integer>(counter);
					results.add(task);
					
					Thread t = new Thread(task);
					t.start();
				} else {
					if(search(file)) {
						count++;
					}
				}
			}
			
			//把文件遍历完后，再对匹配的文件个数进行统计
			for(FutureTask<Integer> result : results) {
				count += result.get();
			}
		} catch (Exception e) {
		}
		
		return count;
	}
	
	private boolean search(File file) {
		try {
			Scanner in = new Scanner(new FileInputStream(file));
			boolean found = false;
			//找到有关键字，返回true
			while(!found && in.hasNextLine()) {
				String line = in.nextLine();
				if(line.contains(keyword)) {
					found = true;
				}
			}
			in.close();
			return found;
		} catch (Exception e) {
			return false;
		}
	}
	
	private int count;
	private File directory;
	private String keyword;
}