How to copy image in java using bufferedreader/writer

问题

    File file = new File("download.png");
    File newfile = new File("D:\\Java.png");
    BufferedReader br=null;
    BufferedWriter bw=null;
    try {
        FileReader fr = new FileReader(file);
        FileWriter fw = new FileWriter(newfile);
        br = new BufferedReader(fr);
        bw = new BufferedWriter(fw);
        char[] buf = new char[1024];
        int bytesRead;
        while ((bytesRead = br.read(buf)) > 0) {
            bw.write(buf, 0, bytesRead);
        }
        bw.flush();
        }
        catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            br.close();
        bw.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        }

Whats wrong with this code. Is it possible with BufferedReader and Writer Class?? I know how to to make copy of image using InputStream and OutputStream, So don't paste solution using that!!

回答1:

Whats wrong with this code.

You're using text-based classes for binary data.

Is it possible with BufferedReader and Writer Class?

Not while you're dealing with binary data, no.

I know how to to make copy of image using InputStream and OutputStream, So don't paste solution using that!

That's the solution you should use, because those are the classes designed for binary data.

Fundamentally, using Reader or Writer for non-text data is broken, and asking for trouble. If you open up the file in a text editor and don't see text, it's not a text file... (Alternatively, it could be a text file that you're using the wrong encoding for, but things like images and sound aren't naturally text.)

回答2:

Use javax.imageio.ImageIO utility class, which has lots of utility method related to images processing.

try{
    File imagefile = new File("download.png");
    BufferedImage image = ImageIO.read(imagefile);
    ImageIO.write(image, "png",new File("D:\\Java.png"));
    .....
}

来源：https://stackoverflow.com/questions/42278750/how-to-copy-image-in-java-using-bufferedreader-writer