MultipartFile与File互转&inputStream转File

很多时候，在对文件上传和下载的时候，内置的MultipartFile文件类型有时候并不符合我们的操作要求，需要对MultipartFile文件类型进行转换。

	/**
	 * MultipartFile 转 File
	 * 
	 * @param file
	 * @throws Exception
	 */
	public static void multipartFileToFile(@RequestParam MultipartFile file) throws Exception {
		File toFile = null;
		if (file.equals("") || file.getSize() <= 0) {
			file = null;
		} else {
			InputStream ins = null;
			ins = file.getInputStream();
			toFile = new File(file.getOriginalFilename());
			inputStreamToFile(ins, toFile);
			ins.close();
		}
	}

	/**
	 * File 转 MultipartFile
	 * 
	 * @param file
	 * @throws Exception
	 */
	public static void fileToMultipartFile(File file) throws Exception {
		FileInputStream fileInput = new FileInputStream(file);
		MultipartFile toMultipartFile = new MockMultipartFile("file", file.getName(), "text/plain",
				IOUtils.toByteArray(fileInput));
		toMultipartFile.getInputStream();
	}

	/**
	 * InputStream 转 File
	 * 
	 * @param ins
	 * @param file
	 */
	public static void inputStreamToFile(InputStream ins, File file) {
		try {
			OutputStream os = new FileOutputStream(file);
			int bytesRead = 0;
			byte[] buffer = new byte[8192];
			while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {
				os.write(buffer, 0, bytesRead);
			}
			os.close();
			ins.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}