package com.reactnative.horsepush;

import java.io.File;
import java.io.FileInputStream;
import java.math.BigInteger;
import java.security.MessageDigest;

/**
 * 
 * @author 68xg.com
 * 
 */
public class HorsePushMd5 {
	private static char md5Chars[] = { '0', '1', '2', '3', '4', '5', '6', '7',
			'8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	private static MessageDigest messagedigest;

//	/* 获取一个文件的md5码 */
//	public static String getFileMD5String(File file)   {
//		String md5Str="";
//		try {
//			messagedigest = MessageDigest.getInstance("MD5");
//			FileInputStream in = new FileInputStream(file);
//			FileChannel ch = in.getChannel();
//			MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0,
//					file.length());
//			messagedigest.update(byteBuffer);
//
//			md5Str = bufferToHex(messagedigest.digest());
//		}catch (Exception e){ }
//		return md5Str;
//	}


	public static String getFileMD5String(File file) {
		if (!file.isFile()) {
			return "";
		}
		MessageDigest digest = null;
		FileInputStream in = null;
		byte buffer[] = new byte[1024];
		int len;
		try {
			digest = MessageDigest.getInstance("MD5");
			in = new FileInputStream(file);
			while ((len = in.read(buffer, 0, 1024)) != -1) {
				digest.update(buffer, 0, len);
			}
			in.close();
		} catch (Exception e) {
			return "";
		}
		BigInteger bigInt = new BigInteger(1, digest.digest());
		return bigInt.toString(16);
	}


	/* 获取一个字符串的md5码 */
	public static String getStringMD5String(String str) throws Exception {
		messagedigest = MessageDigest.getInstance("MD5");
		messagedigest.update(str.getBytes());
		return bufferToHex(messagedigest.digest());
	}

	/* 验证一个字符串和一个MD5码是否相等 */
	public static boolean check(String str, String md5) throws Exception {
		if (getStringMD5String(str).equals(md5))
			return true;
		else
			return false;
	}

	/* 验证一个文件和一个MD5码是否相等 */
	public static boolean check(File f, String md5) throws Exception {
		if (getFileMD5String(f).equals(md5))
			return true;
		else
			return false;
	}

	private static String bufferToHex(byte bytes[]) {
		return bufferToHex(bytes, 0, bytes.length);
	}

	private static String bufferToHex(byte bytes[], int m, int n) {
		StringBuffer stringbuffer = new StringBuffer(2 * n);
		int k = m + n;
		for (int l = m; l < k; l++) {
			appendHexPair(bytes[l], stringbuffer);
		}
		return stringbuffer.toString();
	}

	private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
		char c0 = md5Chars[(bt & 0xf0) >> 4];
		char c1 = md5Chars[bt & 0xf];
		stringbuffer.append(c0);
		stringbuffer.append(c1);
	}

}