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This article mainly explains "what are the ways to copy and cut files in java". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's way of thinking to study and learn "what are the ways to copy and cut files in java".

I. copy of files

The traditional method of file copy in IO, using the input and output stream, is actually recreating and writing a file. If the target file already exists, overwrite it, recreate a file, and write the data. This method is not friendly enough to overwrite the original file without giving any hint, which may lead to the loss of the original data.

@ Testvoid testCopyFile1 () throws IOException {File fromFile = newFile ("D:\ data\\ test\\ newFile.txt"); File toFile = newFile ("D:\ data\\ test2\\ copyedFile.txt"); try (InputStream inStream = new FileInputStream (fromFile); OutputStream outStream = new FileOutputStream (toFile);) {byte [] buffer = new byte [1024]; int length While ((length = inStream.read (buffer)) > 0) {outStream.write (buffer, 0, length); outStream.flush ();}

The method of file copy in Java NIO is simple to use. FileAlreadyExistsException is thrown when the target file already exists, NoSuchFileException is thrown when the source file does not exist, and different Exception is given for different exception scenarios, which is more helpful for us to write more robust programs.

@ Testvoid testCopyFile2 () throws IOException {Path fromFile = Paths.get ("D:\ data\\ test\\ newFile.txt"); Path toFile = Paths.get ("D:\ data\\ test2\\ copyedFile.txt"); Files.copy (fromFile, toFile);}

If you do not want to throw a FileAlreadyExistsException but overwrite it when the target file already exists, you can also choose to use the following options flexibly

StandardCopyOption.REPLACE_EXISTING to ignore the exception that already exists in the file, and overwrite it if it exists

/ / replace the target file Files.copy (fromFile, toFile, StandardCopyOption.REPLACE_EXISTING) if it exists

The properties of the StandardCopyOption.COPY_ATTRIBUTES copy file, the last modification time, the last access time and other information, not only the contents of the copy file, but also the attributes attached to the file are copied.

CopyOption [] options = {StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES / / copy file attributes, last modified time, recent access time, etc.}; Files.copy (fromFile, toFile, options); II. File renaming

In NIO, you can use the Files.move method to move files within the same folder and change the name. When the target file already exists, there is also a FileAlreadyExistsException, and you can also use StandardCopyOption to handle the exception.

@ Testvoid testRenameFile () throws IOException {Path source = Paths.get ("D:\ data\\ test\\ newFile.txt"); Path target = Paths.get ("D:\ data\\ test\\ renameFile.txt"); / / replace the REPLACE_EXISTING file Files.move (source, target,StandardCopyOption.REPLACE_EXISTING) if it exists;}

The effect of the following implementation is the same as that of the code above, and the resolveSibling function is to merge the parent path of the source file with the parameter file name into a new file path.

Resolve series functions deal with path delimiter, path and file name merging in various systems such as windows and linux, which has better operating system compatibility than their own handwritten code to deal with path delimiter and path and file name merging of different operating systems.

@ Testvoid testRenameFile2 () throws IOException {Path source = Paths.get ("D:\ data\\ test\\ newFile.txt"); / / this way of writing is simpler and more compatible with Files.move (source, source.resolveSibling ("renameFile.txt"));}

Traditional IO uses the renameTo method of the File class to rename. If it fails, it returns false without any exception thrown. You don't know the reason for your failure, because the source file doesn't exist. Or did it fail because the target file already exists? Therefore, the author does not recommend using this method.

@ Testvoid testRenameFile3 () throws IOException {File source = newFile ("D:\ data\\ test\\ newFile.txt"); boolean succeeded = source.renameTo (newFile ("D:\ data\\ test\\ renameFile.txt"); System.out.println (succeeded); / / failed false, no exception} 3. File cut

File clipping is actually still Files.move. If the destination folder of move does not exist or the source file does not exist, NoSuchFileException will be thrown.

@ Testvoid testMoveFile () throws IOException {Path fromFile = Paths.get ("D:\ data\\ test\\ newFile.txt"); / / File Path anotherDir = Paths.get ("D:\ data\\ test\\ anotherDir"); / / destination folder Files.createDirectories (anotherDir); Files.move (fromFile, anotherDir.resolve (fromFile.getFileName ()), StandardCopyOption.REPLACE_EXISTING);}

The resolve function parses the anotherDir path and merges the parameter file name into a new file path.

Thank you for reading, these are the contents of "what are the ways to copy and cut files in java?" after the study of this article, I believe you have a deeper understanding of the way of copying and cutting files in java, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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