用了t-io很长时间了，但是没有深层次的 阅读代码，写本篇博客为了记录下 对 tio 协议（Packet）中 消息头的长度（HEADER_LENGTH）的理解
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import org.nutz.log.Log;
import org.nutz.log.Logs;
public class ByteBufferTest {
private static final Log log = Logs.get();
private final static byte MSG_TYPE = 8;
public static void main(String[] args) throws Exception{
/**
* 消息头的长度 1+4
* 所谓 1 是 协议定义的消息类型 例如 byte MSG_TYPE = 8; 占一个字节
* 所谓 4 是 消息体的长度 int类型 占4个字节
*/
int headerLen = 5;
String body = "hello tio";
int bodyLen = body.length();//消息体长度
int allLen = headerLen + bodyLen;
ByteBuffer buffer = null;
buffer = ByteBuffer.allocate(allLen);
buffer.order(ByteOrder.BIG_ENDIAN);
buffer.put(ByteBufferTest.MSG_TYPE);
log.infof("[encode1]-limit=%s,position=%s", buffer.limit(),buffer.position());
buffer.putInt(bodyLen);
log.infof("[encode2]-limit=%s,position=%s", buffer.limit(),buffer.position());
buffer.put(new String(body).getBytes("UTF-8"));
log.infof("[encode3]-limit=%s,position=%s", buffer.limit(),buffer.position());
buffer.position(0);
byte type = buffer.get();//消息类型
System.out.println("消息类型:" + type);
int bodyLength = buffer.getInt();//消息体长度
System.out.println("消息体长度:" + bodyLength);
byte[] dst = new byte[bodyLength];//消息内容
buffer.get(dst);
System.out.println("消息内容:" + new String(dst));
}
/**
* int 转byte
* int 类型 占4个字节
* @param val
* @return
*/
public static byte[] intToByte(int val){
byte[] b = new byte[4];
b[0] = (byte)(val & 0xff);
b[1] = (byte)((val >> 8) & 0xff);
b[2] = (byte)((val >> 16) & 0xff);
b[3] = (byte)((val >> 24) & 0xff);
return b;
}
}
