package org.springblade.mdm.utils;

import java.io.*;
import java.util.Arrays;

public class CustomBinaryReader {
	/**
	 * 从输入流读取数据到输出流
	 * @param inputStream
	 * @param os
	 * @throws IOException
	 */
	public static void read(InputStream inputStream, OutputStream os) throws IOException {
		byte[] buffer = new byte[1024];
		try (DataInputStream in = new DataInputStream(
			new BufferedInputStream(inputStream))) {

			// 读取并验证Magic Number
			byte[] magic = new byte[4];
			in.readFully(magic);
			if (!Arrays.equals(magic, CustomBinaryWriter.MAGIC_NUMBER)) {
				throw new RuntimeException("不是有效的自定义文件格式");
			}

			// 读取版本号
			short version = in.readShort();
			if (version > CustomBinaryWriter.VERSION) {
				throw new RuntimeException("不支持的版本: " + version);
			}

			while(in.read(buffer) != -1){
				os.write(buffer);
			}

		}
	}
}