例子代码走起，
MD5 md5sum = new MD5();
md5sum.md5sum("/sdcard/xxx/yy.java");
MD5类文件：
import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;
public class MD5 {
private static final char HEX_DIGITS[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F' };
public MD5() {
// System.out.println(md5sum("/init.rc"));
}
// public static void main(String[] args)
//{
// System.out.println(md5sum("/init.rc"));
//}
public static String toHexString(byte[] b) {
StringBuilder sb = new StringBuilder(b.length * 2);
for (int i = 0; i < b.length; i++) {
sb.append(HEX_DIGITS[(b[i] & 0xf0) >>> 4]);
sb.append(HEX_DIGITS[b[i] & 0x0f]);
}
return sb.toString();
}
public String md5sum(String filename) {
InputStream fis;
byte[] buffer = new byte[1024];
int numRead = 0;
MessageDigest md5;
try{
fis = new FileInputStream(filename);
md5 = MessageDigest.getInstance("MD5");
while((numRead=fis.read(buffer)) > 0) {
md5.update(buffer,0,numRead);
}
fis.close();
return toHexString(md5.digest());
} catch (Exception e) {
System.out.println("error");
return null;
}
}
}
