79

我想将文件从一个位置复制到 Java 中的另一个位置。做这个的最好方式是什么？

这是我到目前为止所拥有的：

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;
public class TestArrayList {
    public static void main(String[] args) {
        File f = new File(
            "D:\\CBSE_Demo\\Demo_original\\fscommand\\contentplayer\\config");
        List<String>temp=new ArrayList<String>();
        temp.add(0, "N33");
        temp.add(1, "N1417");
        temp.add(2, "N331");
        File[] matchingFiles = null;
        for(final String temp1: temp){
            matchingFiles = f.listFiles(new FilenameFilter() {
                public boolean accept(File dir, String name) {
                    return name.startsWith(temp1);
                }
            });
            System.out.println("size>>--"+matchingFiles.length);

        }
    }
}

这不会复制文件，最好的方法是什么？

4

8 回答 8

134

您可以使用此（或任何变体）：

Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING);

此外，我建议使用File.separatoror/而不是\\使其兼容多个操作系统，有关此问题的问题/答案可在此处获得。

由于您不确定如何临时存储文件，请查看ArrayList：

List<File> files = new ArrayList();
files.add(foundFile);

要将List文件移动到单个目录中：

List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
    Files.copy(file.toPath(),
        (new File(path + file.getName())).toPath(),
        StandardCopyOption.REPLACE_EXISTING);
}
于 2013-05-08T06:20:06.023 回答
81

使用流

private static void copyFileUsingStream(File source, File dest) throws IOException {
    InputStream is = null;
    OutputStream os = null;
    try {
        is = new FileInputStream(source);
        os = new FileOutputStream(dest);
        byte[] buffer = new byte[1024];
        int length;
        while ((length = is.read(buffer)) > 0) {
            os.write(buffer, 0, length);
        }
    } finally {
        is.close();
        os.close();
    }
}

使用频道

private static void copyFileUsingChannel(File source, File dest) throws IOException {
    FileChannel sourceChannel = null;
    FileChannel destChannel = null;
    try {
        sourceChannel = new FileInputStream(source).getChannel();
        destChannel = new FileOutputStream(dest).getChannel();
        destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
       }finally{
           sourceChannel.close();
           destChannel.close();
       }
}

使用 Apache Commons IO 库：

private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
    FileUtils.copyFile(source, dest);
}

使用 Java SE 7 Files 类：

private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
    Files.copy(source.toPath(), dest.toPath());
}

或者试试谷歌番石榴：

https://github.com/google/guava

文档： https ://guava.dev/releases/snapshot-jre/api/docs/com/google/common/io/Files.html

比较时间：

    File source = new File("/Users/sidikov/tmp/source.avi");
    File dest = new File("/Users/sidikov/tmp/dest.avi");


    //copy file conventional way using Stream
    long start = System.nanoTime();
    copyFileUsingStream(source, dest);
    System.out.println("Time taken by Stream Copy = "+(System.nanoTime()-start));
     
    //copy files using java.nio FileChannel
    source = new File("/Users/sidikov/tmp/sourceChannel.avi");
    dest = new File("/Users/sidikov/tmp/destChannel.avi");
    start = System.nanoTime();
    copyFileUsingChannel(source, dest);
    System.out.println("Time taken by Channel Copy = "+(System.nanoTime()-start));
     
    //copy files using apache commons io
    source = new File("/Users/sidikov/tmp/sourceApache.avi");
    dest = new File("/Users/sidikov/tmp/destApache.avi");
    start = System.nanoTime();
    copyFileUsingApacheCommonsIO(source, dest);
    System.out.println("Time taken by Apache Commons IO Copy = "+(System.nanoTime()-start));
     
    //using Java 7 Files class
    source = new File("/Users/sidikov/tmp/sourceJava7.avi");
    dest = new File("/Users/sidikov/tmp/destJava7.avi");
    start = System.nanoTime();
    copyFileUsingJava7Files(source, dest);
    System.out.println("Time taken by Java7 Files Copy = "+(System.nanoTime()-start));
于 2015-09-18T13:12:18.947 回答
9

在 Java >=7 中使用 New Java File 类。

创建以下方法并导入必要的库。

public static void copyFile( File from, File to ) throws IOException {
    Files.copy( from.toPath(), to.toPath() );
}

在 main 中使用如下创建的方法：

File dirFrom = new File(fileFrom);
File dirTo = new File(fileTo);

try {
        copyFile(dirFrom, dirTo);
} catch (IOException ex) {
        Logger.getLogger(TestJava8.class.getName()).log(Level.SEVERE, null, ex);
}

注意：- fileFrom 是您要复制到不同文件夹中的新文件 fileTo 的文件。

学分 - @Scott：用 Java 复制文件的标准简洁方法？

于 2015-05-19T14:04:25.023 回答
6 
  public static void copyFile(File oldLocation, File newLocation) throws IOException {
        if ( oldLocation.exists( )) {
            BufferedInputStream  reader = new BufferedInputStream( new FileInputStream(oldLocation) );
            BufferedOutputStream  writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
            try {
                byte[]  buff = new byte[8192];
                int numChars;
                while ( (numChars = reader.read(  buff, 0, buff.length ) ) != -1) {
                    writer.write( buff, 0, numChars );
                }
            } catch( IOException ex ) {
                throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
            } finally {
                try {
                    if ( reader != null ){                      
                        writer.close();
                        reader.close();
                    }
                } catch( IOException ex ){
                    Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() ); 
                }
            }
        } else {
            throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
        }
    }
于 2013-09-09T06:31:22.753 回答
1

文件.exists()

文件.createDirectory()

文件.copy()

覆盖现有文件：Files.move()

文件.delete()

Files.walkFileTree() 在此处输入链接描述

于 2019-01-05T12:44:29.143 回答
1

将文件从一个位置复制到另一个位置意味着，需要将整个内容复制到另一个位置。Files.copy(Path source, Path target, CopyOption... options) throws IOException此方法期望源位置是原始文件位置，目标位置是目标位置相同的新文件夹位置（与原始文件相同）。目标位置需要存在于我们的系统中，否则我们需要创建一个文件夹位置，然后在该文件夹位置我们需要创建一个与原始文件名同名的文件。然后使用复制功能，我们可以轻松地从一个位置复制文件给其他。

 public static void main(String[] args) throws IOException {
                String destFolderPath = "D:/TestFile/abc";
                String fileName = "pqr.xlsx";
                String sourceFilePath= "D:/TestFile/xyz.xlsx";
                File f = new File(destFolderPath);
                if(f.mkdir()){
                    System.out.println("Directory created!!!!");
                }
                else {
                    System.out.println("Directory Exists!!!!");
                }
                f= new File(destFolderPath,fileName);
                if(f.createNewFile())   {

                    System.out.println("File Created!!!!");
                }   else {
                    System.out.println("File exists!!!!");
                }

                Files.copy(Paths.get(sourceFilePath), Paths.get(destFolderPath, fileName),REPLACE_EXISTING);
                System.out.println("Copy done!!!!!!!!!!!!!!");


            }
于 2019-02-05T11:33:15.037 回答
1

您可以使用Java 8 Streaming API、PrintWriter和Files API来实现

try (PrintWriter pw = new PrintWriter(new File("destination-path"), StandardCharsets.UTF_8)) {
    Files.readAllLines(Path.of("src/test/resources/source-file.something"), StandardCharsets.UTF_8)
         .forEach(pw::println);
}

如果您想在复制时即时修改内容，请查看此链接以获取扩展示例 https://overflowed.dev/blog/copy-file-and-modify-with-java-streams/

于 2021-04-20T12:35:12.810 回答
0

我修改了其中一个答案以使其更有效率。

public void copy(){
    InputStream in = null;
    try {
        in = new FileInputStream(Files);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    try {
        OutputStream out = new FileOutputStream();
        try {
            // Transfer bytes from in to out
            byte[] buf = new byte[1024];
            while (true) {
                int len = 0;
                try {
                    if (!((len = in.read(buf)) > 0)) break;
                } catch (IOException e) {
                    e.printStackTrace();
                }
                try {
                    out.write(buf, 0, len);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        } finally {
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    } finally {
        try {
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

private void moveFile() {
    copy();
    File dir = getFilesDir();
    File file = new File(dir, "my_filename");
    boolean deleted = file.delete();
}
于 2022-02-09T17:18:56.603 回答