private void assertMsg(Message msg) {
assertNotNull(msg);
assertEquals(9999L, msg.getId());
assertEquals("test", msg.getTopic());
assertFalse(msg.hasAttribute());
assertEquals(0, MessageAccessor.getFlag(msg));
assertEquals("hello", new String(msg.getData()));
}
/**
* 从binary数据中解出消息
*
* @param topic
* @param data
* @param offset
* @return
* @throws InvalidMessageException
*/
public static final DecodedMessage decodeMessage(
final String topic, final byte[] data, final int offset) throws InvalidMessageException {
final ByteBuffer buf = ByteBuffer.wrap(data, offset, HEADER_LEN);
final int msgLen = buf.getInt();
final int checksum = buf.getInt();
vailidateMessage(offset + HEADER_LEN, msgLen, checksum, data);
final long id = buf.getLong();
// 取flag
final int flag = buf.getInt();
String attribute = null;
int payLoadOffset = offset + HEADER_LEN;
int payLoadLen = msgLen;
if (payLoadLen > MAX_READ_BUFFER_SIZE) {
throw new InvalidMessageException("Too much long payload length:" + payLoadLen);
}
// 如果有属性，需要解析属性
if (MessageFlagUtils.hasAttribute(flag)) {
// 取4个字节的属性长度
final int attrLen = getInt(offset + HEADER_LEN, data);
// 取消息属性
final byte[] attrData = new byte[attrLen];
System.arraycopy(data, offset + HEADER_LEN + 4, attrData, 0, attrLen);
attribute = ByteUtils.getString(attrData);
// 递增payloadOffset，加上4个字节的消息长度和消息长度本身
payLoadOffset = offset + HEADER_LEN + 4 + attrLen;
// payload长度递减，减去4个字节的消息长度和消息长度本身
payLoadLen = msgLen - 4 - attrLen;
}
// 获取payload
final byte[] payload = new byte[payLoadLen];
System.arraycopy(data, payLoadOffset, payload, 0, payLoadLen);
final Message msg = new Message(topic, payload);
MessageAccessor.setFlag(msg, flag);
msg.setAttribute(attribute);
MessageAccessor.setId(msg, id);
return new DecodedMessage(
payLoadOffset + payLoadLen,
msg,
ByteBuffer.wrap(data, offset, payLoadOffset + payLoadLen - offset));
}