Best Way to Write Bytes in the Middle of a File in Java

问题

What is the best way to write bytes in the middle of a file using Java?

回答1:

Reading and Writing in the middle of a file is as simple as using a RandomAccessFile in Java.

RandomAccessFile, despite its name, is more like an InputStream and OutputStream and less like a File. It allows you to read or seek through bytes in a file and then begin writing over whichever bytes you care to stop at.

Once you discover this class, it is very easy to use if you have a basic understanding of regular file i/o.

A small example:

public static void aMethod(){
    RandomAccessFile f = new RandomAccessFile(new File("whereDidIPutTHatFile"), "rw");
    long aPositionWhereIWantToGo = 99;
    f.seek(aPositionWhereIWantToGo); // this basically reads n bytes in the file
    f.write("Im in teh fil, writn bites".getBytes());
    f.close();
}

回答2:

Use RandomAccessFile

• Tutorial
• Javadocs

回答3:

Open the file in write mode without truncating it, seek to the desired offset, and write the desired data. Just be careful about text/binary mode.

回答4:

I think it’s best to create file chunks every time. And when the file is downloaded, connect them together. Now I'm working on it.

来源：https://stackoverflow.com/questions/181408/best-way-to-write-bytes-in-the-middle-of-a-file-in-java