java - 文件上传后重命名文件

Question

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);
                  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);
                  }
        }

我的问题是当我上传图片类型png(例如aaa.png)时，它可以在服务器上上传但不能重命名，上传aaa.png并且我重新上传此图片(aaa.png)后它可以更改名称但它有 2 个文件，一个是 aaa.png，一个是 macback.png

我的代码有什么问题？

谢谢!

Answer 1

我认为您正在尝试执行以下操作:

1. 上传文件时，您希望将其命名为 macback.png，而不是其原始文件名。
2. 上传第二个文件时，您需要先将 macback.png 重命名为 bg.png，然后将上传的文件另存为 macback.png。

如果是这种情况，首先您需要测试 macback.png 文件是否存在，如果存在则将其重命名。然后，为 macback.png 文件创建一个 File 对象，并打开该文件的 FileOutputStream 以将上传的文件写入其中。

类似这样的事情:

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);
    }
}