CompletableFuture實體(一)_求教多執行緒拷貝指定目錄方案

import java.io.IOException;

import java.nio.file.FileSystems;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.attribute.BasicFileAttributes;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.Objects;

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.TimeUnit;



public class Test {

    private static final ExecutorService serivce = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());



    public Test() {

        // TODO Auto-generated constructor stub

    }



    private static List<CompletableFuture<Void>> execFileCopy(String src, String tar) {

        List<CompletableFuture<Void>> lst = Collections.synchronizedList(new ArrayList<CompletableFuture<Void>>());



        try {

            Path target = FileSystems.getDefault().getPath(tar);

            Files.walkFileTree(Paths.get(src), new SimpleFileVisitor<Path>() {

                public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {

                    Objects.requireNonNull(dir);

                    Objects.requireNonNull(attrs);

                    Path targetPath = target.resolve(dir.subpath(0, dir.getNameCount()));

                    Files.createDirectories(targetPath);

                    return FileVisitResult.CONTINUE;

                }



                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {

                    Objects.requireNonNull(file);

                    Path targetPath = target.resolve(file.subpath(0, file.getNameCount()));

                    lst.add(CompletableFuture.runAsync(() -> {

                        try {

                            Files.copy(file, targetPath);

                        } catch (IOException e) {

                            // TODO Auto-generated catch block

                            e.printStackTrace();

                        }

                    }, serivce));

                    return FileVisitResult.CONTINUE;

                }

            });

        } catch (IOException e) {

            e.printStackTrace();

        }

        return lst;

    }



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

        long s = System.currentTimeMillis();

        String tar = "E:\\3";

        String src = "F:\\angular2"; // 共734M大小目錄 內含386M檔案(1)、185M檔案(1)、其余26，918個檔案均為K級碎片檔案

        

        List<CompletableFuture<Void>> list = execFileCopy(src, tar);

        CompletableFuture<Void> controlFuture = CompletableFuture.allOf(list.toArray(new CompletableFuture[]{}));

        while(!controlFuture.isDone()) {}

        System.out.println("exception found: " + controlFuture.isCompletedExceptionally());

        

        System.out.println((System.currentTimeMillis() - s) / 1000); // 耗時27秒 系統環境（i5-3337U 4G記憶體 256GSSD硬碟 Win10）

    }

}

標籤：Java SE

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