Question

我想知道如何从Vaadin上传组件中获取文件。以下是Vaadin Website的示例但除了OutputStreams之外，它不包括如何保存它。救命啊！

Answer 1

要在Vaadin中接收文件上传，您必须实现Receiver界面，它为您提供receiveUpload(filename, mimeType)方法，用于接收信息。执行此操作的最简单的代码是（以Vaadin 7 docs为例）：

class FileUploader implements Receiver {
    private File file;
    private String BASE_PATH="C:\";

    public OutputStream receiveUpload(String filename,
                                  String mimeType) {
        // Create upload stream
        FileOutputStream fos = null; // Stream to write to
        try {
            // Open the file for writing.
            file = new File(BASE_PATH + filename);
            fos = new FileOutputStream(file);
        } catch (final java.io.FileNotFoundException e) {
            new Notification("Could not open file<br/>",
                         e.getMessage(),
                         Notification.Type.ERROR_MESSAGE)
            .show(Page.getCurrent());
            return null;
        }
        return fos; // Return the output stream to write to
    }
};

有了这个，Uploader会在C:\中写一个文件。如果您希望在上传成功完成后获得某些内容，则可以实施SucceeddedListener或FailedListener。以上面的例子为例，结果（SucceededListener）可以是：

class FileUploader implements Receiver {
    //receiveUpload implementation

    public void uploadSucceeded(SucceededEvent event) {
        //Do some cool stuff here with the file
    }
}

如何保存上传的文件

1 个答案: