/**
* Converts the payload to the binary form.
*
* @return Binary representation of the payload
*/
private String getBinaryPayload() {
final StringBuilder builder = new StringBuilder();
for (final Fragment fragment : fragments) {
for (int i : fragment.getPayload().toCharArray()) {
if (i < 89) {
i -= 48;
} else {
i -= 56;
}
final StringBuilder binary = new StringBuilder(Integer.toBinaryString(i));
while (binary.length() < 6) {
binary.insert(0, "0");
}
builder.append(binary);
}
}
return builder.toString();
}
/**
* Adds a fragment to the assembler.
*
* @param fragment An AIS message fragment
* @return an assembled message or null if the message is not complete
*/
public RawMessage addFragment(final Fragment fragment) {
final int actualFragment = fragment.getCurrentFragment();
final int totalFragments = fragment.getTotalFragments();
final int expectedFragment = fragments.size() + 1;
if (actualFragment == expectedFragment) {
fragments.add(fragment);
} else {
fragments.clear();
if (actualFragment == 1) {
fragments.add(fragment);
}
}
RawMessage message = null;
if (totalFragments == fragments.size()) {
message = new RawMessage();
message.setFragments(new ArrayList<Fragment>(fragments));
message.setBinary(getBinaryPayload());
fragments.clear();
}
return message;
}