第一版
代码如下，非常简单：
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
|
public class TimeClientHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
ByteBuf m = (ByteBuf) msg; // (1)
try {
long currentTimeMillis = (m.readUnsignedInt() - 2208988800L) * 1000L;
System.out.println(new Date(currentTimeMillis));
ctx.close();
} finally {
m.release();
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
ctx.close();
}
}
|
第二版
代码如下，还没有写过这种类型的代码：
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
|
public class TimeClientHandler2 extends ChannelInboundHandlerAdapter {
private ByteBuf buf;
@Override
public void handlerAdded(ChannelHandlerContext ctx) {
buf = ctx.alloc().buffer(4);
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) {
buf.release();
buf = null;
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
ByteBuf m = (ByteBuf) msg;
buf.writeBytes(m);
m.release();
if (buf.readableBytes() >= 4) {
long currentTimeMillis = (buf.readUnsignedInt() - 2208988800L) * 1000L;
System.out.println(new Date(currentTimeMillis));
ctx.close();
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
ctx.close();
}
}
|
在handlerRemove中清理掉创建的缓存是一个非常棒的写法。
参考资料
- Writing a Time Client 写个时间客户端
- Dealing with a Stream-based Transport 处理一个基于流的传输