rename file after file upload

public void handleFileUpload(FileUploadEvent event) {


         ExternalContext extContext = FacesContext.getCurrentInstance().getExternalContext();
              File result = new File(extContext.getRealPath("//admin//images") + "//" + event.getFile().getFileName());
           // File result = new File("D:\\Netbeans Project\\mcGrawLibPro\\mcGrawLibPro-war\\web\\item", event.getFile().getFileName());
              File bg = new File(extContext.getRealPath("//admin//images")+"//macback.png");
            try {




                    bg.renameTo(new File(extContext.getRealPath("//admin//images")+"//bg.png"));
                    File f1 = new File(extContext.getRealPath("//admin//images") + "//macback.png" );
                    result.renameTo(f1);



                //System.out.println(f1);
                System.out.println(result);
                FileOutputStream fileOutputStream = new FileOutputStream(result);

                byte[] buffer = new byte[BUFFER_SIZE];

                int bulk;
                InputStream inputStream = event.getFile().getInputstream();
                while (true) {
                  bulk = inputStream.read(buffer);
                  if (bulk < 0) {
                         break;
                         }
                  fileOutputStream.write(buffer, 0, bulk);
            开发者_JS百科      fileOutputStream.flush();
                  }

                  fileOutputStream.close();
                  inputStream.close();

                  FacesMessage msg = new FacesMessage("OK",
                      event.getFile().getFileName() + " was upload.");
                  FacesContext.getCurrentInstance().addMessage(null, msg);

                  } catch (IOException e) {
                        e.printStackTrace();

                  FacesMessage error = new FacesMessage("Can't upload!");
                  FacesContext.getCurrentInstance().addMessage(null, error);
                  }
        }

my problem is when i upload a picture type png such as aaa.png, it can upload on server but it not rename, after upload aaa.png and i re-upload this picture(aaa.png) it can change name but it have 2 file one is aaa.png and one is macback.png

What's wrong in my code?

Thank you !

Here's what I think you are trying to do:

1. When you upload a file, you want to call it macback.png, not its original file name.
2. When you upload a second file, you want to rename macback.png to bg.png first, then save the uploaded file as macback.png.

If that is the case, first you need to test for the existence of the macback.png file and rename it if it exists. Then you create a File object for the macback.png file and open a FileOutputStream to that file to write the uploaded file to.

Something like this:

public void handleFileUpload(FileUploadEvent event) {
    ExternalContext extContext = FacesContext.getCurrentInstance().getExternalContext();
    File result = new File(extContext.getRealPath("//admin//images") + "//macback.png");
    if(result.exists()) {
        result.renameTo(new File(extContext.getRealPath("//admin//images")+"//bg.png"));
    }

    try {
        File targetFile = new File(extContext.getRealPath("//admin//images") + "//macback.png" );

        FileOutputStream fileOutputStream = new FileOutputStream(targetFile);
        byte[] buffer = new byte[BUFFER_SIZE];

        int bulk;
        InputStream inputStream = event.getFile().getInputstream();
        while (true) {
            bulk = inputStream.read(buffer);
            if (bulk < 0) {
                break;
            }
            fileOutputStream.write(buffer, 0, bulk);
            fileOutputStream.flush();
        }

        fileOutputStream.close();
        inputStream.close();

        FacesMessage msg = new FacesMessage("OK",
        event.getFile().getFileName() + " was upload.");
        FacesContext.getCurrentInstance().addMessage(null, msg);

    } catch (IOException e) {
        e.printStackTrace();

        FacesMessage error = new FacesMessage("Can't upload!");
        FacesContext.getCurrentInstance().addMessage(null, error);
    }
}

Ok, so let's see if I got it this time:

1. You want the first A.png to save as A.png.
2. The second time A.png is uploaded, you want the first A.png to be renamed to macback.png and the second A.png to be stored as A.png.

If that's the case, try this:

public void handleFileUpload(FileUploadEvent event) {
    ExternalContext extContext = FacesContext.getCurrentInstance().getExternalContext();
    File result = new File(extContext.getRealPath("//admin//images") + "//" + event.getFile().getFileName());
    if(result.exists()) {
        result.renameTo(new File(extContext.getRealPath("//admin//images")+"//mackback.png"));
    }

    try {
        File targetFile = new File(extContext.getRealPath("//admin//images") + "//" + event.getFile().getFileName() );

        FileOutputStream fileOutputStream = new FileOutputStream(targetFile);
        byte[] buffer = new byte[BUFFER_SIZE];

        int bulk;
        InputStream inputStream = event.getFile().getInputstream();
        while (true) {
            bulk = inputStream.read(buffer);
            if (bulk < 0) {
                break;
            }
            fileOutputStream.write(buffer, 0, bulk);
            fileOutputStream.flush();
        }

        fileOutputStream.close();
        inputStream.close();

        FacesMessage msg = new FacesMessage("OK",
        event.getFile().getFileName() + " was upload.");
        FacesContext.getCurrentInstance().addMessage(null, msg);

    } catch (IOException e) {
        e.printStackTrace();

        FacesMessage error = new FacesMessage("Can't upload!");
        FacesContext.getCurrentInstance().addMessage(null, error);
    }
}

I believe the issue is you are trying to rename result to f1 too early. At the point where you are calling result.renameTo(f1) you have not yet created the file referenced by result so the rename has no effect. You cannot rename a file before it exists on disk.

Now, you don't really need to rename result. Since you have not created the file, you can simply use f1 as the argument to FileOutputStream instead of result.