当需要对一个大文件计算MD5校验和时，JDK提供的方法速度是非常快的，甚至比操作系统提供的本地工具还要快。详情可以查看这个链接 http://www.twmacinta.com/myjava/fast_md5.php
这里有一个简单的示例，来自 http://www.javalobby.org/java/forums/t84420.html：
public static void main(String[] args) throws NoSuchAlgorithmException, FileNotFoundException {
MessageDigest digest = MessageDigest.getInstance("MD5");
File f = new File("c:\\myfile.txt");
InputStream is = new FileInputStream(f);
byte[] buffer = new byte[8192];
int read = 0;
try {
while( (read = is.read(buffer)) > 0) {
digest.update(buffer, 0, read);
}
byte[] md5sum = digest.digest();
BigInteger bigInt = new BigInteger(1, md5sum);
String output = bigInt.toString(16);
System.out.println("MD5: " + output);
}
catch(IOException e) {
throw new RuntimeException("Unable to process file for MD5", e);
}
finally {
try {
is.close();
}
catch(IOException e) {
throw new RuntimeException("Unable to close input stream for MD5 calculation", e);
}
}
}
如果需要对一个较短字符串进行处理，只要使用String的getBytes方法即可
分享到：
2011-07-13 09:19
浏览 2725
评论
转播
