springboot将MultipartFile转换为File的处理方法

采用流处理的方式，直接调用MultipartFile的getInputStream方法即可。

BufferedReader br = new BufferedReader(new InputStreamReader(file.getInputStream()));
try {
	String read = null;
	while ((read = br.readLine()) != null) {
		result = result + read + "\r\n";
	}
} catch (Exception e) {
	e.printStackTrace();
}