Question

我想将文件从一个位置复制到Java中的另一个位置。这样做的最佳方式是什么？

这是我到目前为止所做的：

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？

Answer 1

您可以使用this（或任何变体）：

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

此外，我建议您使用File.separator或/代替\\，以使其符合多个操作系统，问题/答案可用here。

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);

将List个文件移动到一个目录中：

List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
    Files.copy(file.toPath(),
        (new File(path + file.getName())).toPath(),
        StandardCopyOption.REPLACE_EXISTING);
}

Answer 2

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 lib：

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());
}

效果测试：

    File source = new File("/Users/pankaj/tmp/source.avi");
    File dest = new File("/Users/pankaj/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/pankaj/tmp/sourceChannel.avi");
    dest = new File("/Users/pankaj/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/pankaj/tmp/sourceApache.avi");
    dest = new File("/Users/pankaj/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/pankaj/tmp/sourceJava7.avi");
    dest = new File("/Users/pankaj/tmp/destJava7.avi");
    start = System.nanoTime();
    copyFileUsingJava7Files(source, dest);
    System.out.println("Time taken by Java7 Files Copy = "+(System.nanoTime()-start));

结果：

/*
 * File copy:
 * Time taken by Stream Copy            = 44582575000
 * Time taken by Channel Copy           = 104138195000
 * Time taken by Apache Commons IO Copy = 108396714000
 * Time taken by Java7 Files Copy       = 89061578000
 */

链接：

Answer 3

使用Java中的New Java File类＆gt; = 7。

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中使用如下所示的创建方法：

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是您要复制到新文件fileTo到另一个文件夹的文件。

致谢 - @Scott：Standard concise way to copy a file in Java?

Answer 4

  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() );
        }
    }

Answer 5

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

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/

Answer 6

Files.exists（）

Files.createDirectory（）

Files.copy（）

覆盖现有文件： Files.move（）

Files.delete（）

Files.walkFileTree（） enter link description here

Answer 7

将文件从一个位置复制到另一位置意味着需要将整个内容复制到另一位置。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!!!!!!!!!!!!!!"); }该方法期望源位置是原始文件位置，目标位置是目标位置的新文件夹位置相同类型的文件（与原始文件相同）。目标位置需要在我们的系统中存在，否则我们需要创建一个文件夹位置，然后在该文件夹位置中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人。

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如何将文件从一个位置复制到另一个位置？

7 个答案: