java文件md5验证

代码如下:

File file = new File("d:/1.dat");

FileInputStream fs = new FileInputStream(file);

BufferedInputStream bi = new BufferedInputStream(fs);

ByteArrayOutputStream bo = new ByteArrayOutputStream();

byte[] b = new byte[bi.available()];

int i;

while ((i = bi.read(b, 0, b.length)) != -1)

{

bo.write(b, 0, i);

}

bo.close();

System.out.print(Md5.MD5(new String(bo.toByteArray())));

public final static String MD5(String s)

{

char hexDigits[] = {‘0’, ‘1’, ‘2’, ‘3’, ‘4’, ‘5’, ‘6’, ‘7’, ‘8’, ‘9’, ‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’};

try

{

byte[] strTemp = s.getBytes();

MessageDigest mdTemp = MessageDigest.getInstance("MD5");

mdTemp.update(strTemp);

byte[] md = mdTemp.digest();

int j = md.length;

char str[] = new char[j * 2];

int k = 0;

for (int i = 0; i < j; i++)

{

byte byte0 = md[i];

str[k++] = hexDigits[byte0 >>> 4 & 0xf];

str[k++] = hexDigits[byte0 & 0xf];

}

return new String(str);

}

catch (Exception e)

{

return null;

}

}

Md5.MD5就是通过string生成md5编码.

后来在网上下载了一个看文件的md5编码的软件,和我出来的结果不一样.

查询一些资料,好像应该是读文件签名或者认证的md5,如果文件比较大,也不可能把所有的文件数据读到内存.

如果读文件认证的md5或者文件hashcode的md5