public static void copyFile(File src, File dst) throws IOException
{
    long p = 0, dp, size;
    FileChannel in = null, out = null;

    try
    {
        if (!dst.exists()) dst.createNewFile();

        in = new FileInputStream(src).getChannel();
        out = new FileOutputStream(dst).getChannel();
        size = in.size();

        while ((dp = out.transferFrom(in, p, size)) > 0)
        {
            p += dp;
        }
    }
    finally {
        try
        {
            if (out != null) out.close();
        }
        finally {
            if (in != null) in.close();
        }
    }
}

在Java 7中很容易…

File src = new File("original.txt");
File target = new File("copy.txt");

Files.copy(src.toPath(), target.toPath(), StandardCopyOption.REPLACE_EXISTING);

public static void copyFile(File src, File dst) throws IOException
{
    long p = 0, dp, size;
    FileChannel in = null, out = null;

    try
    {
        if (!dst.exists()) dst.createNewFile();

        in = new FileInputStream(src).getChannel();
        out = new FileOutputStream(dst).getChannel();
        size = in.size();

        while ((dp = out.transferFrom(in, p, size)) > 0)
        {
            p += dp;
        }
    }
    finally {
        try
        {
            if (out != null) out.close();
        }
        finally {
            if (in != null) in.close();
        }
    }
}

我会避免使用像apache commons这样的mega api。这是一个简单的操作，它内置于新的NIO包中的JDK中。在之前的回答中已经链接到它，但是NIO api中的关键方法是新函数“transferTo”和“transferFrom”。

http://java.sun.com/javase/6/docs/api/java/nio/channels/FileChannel.html transferTo(长,长% 20,% 20 java.nio.channels.writablebytechannel)

其中一篇链接的文章展示了如何使用transferFrom将这个函数集成到你的代码中:

public static void copyFile(File sourceFile, File destFile) throws IOException {
    if(!destFile.exists()) {
        destFile.createNewFile();
    }

    FileChannel source = null;
    FileChannel destination = null;

    try {
        source = new FileInputStream(sourceFile).getChannel();
        destination = new FileOutputStream(destFile).getChannel();
        destination.transferFrom(source, 0, source.size());
    }
    finally {
        if(source != null) {
            source.close();
        }
        if(destination != null) {
            destination.close();
        }
    }
}

学习NIO可能有点棘手，所以在尝试一夜之间学习NIO之前，您可能想要相信这个机制。从个人经验来看，如果你没有经验，并且是通过java介绍到IO的，那么学习它可能是一件非常困难的事情。io流。

快速和工作与所有版本的Java和Android:

private void copy(final File f1, final File f2) throws IOException {
    f2.createNewFile();

    final RandomAccessFile file1 = new RandomAccessFile(f1, "r");
    final RandomAccessFile file2 = new RandomAccessFile(f2, "rw");

    file2.getChannel().write(file1.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, f1.length()));

    file1.close();
    file2.close();
}

现在在Java 7中，你可以使用下面的try-with-resource语法:

public static void copyFile( File from, File to ) throws IOException {

    if ( !to.exists() ) { to.createNewFile(); }

    try (
        FileChannel in = new FileInputStream( from ).getChannel();
        FileChannel out = new FileOutputStream( to ).getChannel() ) {

        out.transferFrom( in, 0, in.size() );
    }
}

或者，更好的是，这也可以使用Java 7中引入的新Files类来完成:

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

很时髦，是吧?