Java IO.pdf - Nguyen Dang Binh

public class EasyDigestOutputStream extends FilterOutputStream {
private boolean on = true;
private boolean closed = false;
protected byte[] result = null;
protected MessageDigest digest;
public EasyDigestOutputStream(OutputStream out, String algorithm)
throws NoSuchAlgorithmException {
super(out);
digest = MessageDigest.getInstance(algorithm);
}
public EasyDigestOutputStream(OutputStream out, String algorithm,
String provider) throws NoSuchAlgorithmException,
NoSuchProviderException {
super(out);
digest = MessageDigest.getInstance(algorithm, provider);
}
{
}
public void write(int b) throws IOException {
if (on) digest.update((byte)b);
out.write(b);
}
Java I/O
public void write(byte[] data, int offset, int length) throws IOException
}
if (on) digest.update(data, offset, length);
out.write(data, offset, length);
public void on(boolean on) {
this.on = on;
}
public void close() throws IOException {
out.close();
result = digest.digest();
closed = true;
}
public byte[] getDigest() {
return result;
}
Example 10.5 is similar to the FileDigest of Example 10.3 rewritten to use the
EasyDigestOutputStream. This program produces the same digests as Example 10.3, but it's
quite a bit shorter and doesn't require any explicit mucking around with MessageDigest
objects. That's all hidden inside the EasyDigestOutputStream class.
Example 10.5. EasyFileDigest
import java.net.*;
import java.io.*;
import com.macfaq.security.*;
import com.macfaq.io.*;
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