/**
* 消息位置序列化为:
*
* <ul>
* <li>8个字节的offset
* <li>4个字节的长度
* <li>4个字节checksum:这是指整个消息存储数据的checksum，跟message的checksum不同
* <li>4个字节长度，存储的分区名的长度
* <li>存储的分区名
* </ul>
*
* @return
*/
public ByteBuffer encode() {
if (this.buf == null) {
final byte[] storeDescBytes = ByteUtils.getBytes(this.storeDesc);
final ByteBuffer buf = ByteBuffer.allocate(4 + 4 + 8 + 4 + this.storeDesc.length());
buf.putLong(this.getOffset());
buf.putInt(this.getLength());
buf.putInt(this.checksum);
buf.putInt(storeDescBytes.length);
buf.put(storeDescBytes);
buf.flip();
this.buf = buf;
}
return this.buf;
}
/**
* 将消息属性和消息payload打包，结构如下：</br></br> 0或者1个定长attribute + payload
*
* @param message
* @return
*/
public static final byte[] encodePayload(final Message message) {
final byte[] payload = message.getData();
final String attribute = message.getAttribute();
byte[] attrData = null;
if (attribute != null) {
attrData = ByteUtils.getBytes(attribute);
} else {
return payload;
}
final int attrLen = attrData == null ? 0 : attrData.length;
final ByteBuffer buffer = ByteBuffer.allocate(4 + attrLen + payload.length);
if (attribute != null) {
buffer.putInt(attrLen);
if (attrData != null) {
buffer.put(attrData);
}
}
buffer.put(payload);
return buffer.array();
}
