我的帧解码器有以下代码:
protected Object decode(ChannelHandlerContext channelHandlerContext,
Channel channel, ChannelBuffer channelBuffer) throws Exception {
//Header 1 + 4 length bytes
if (channelBuffer.readableBytes() < 5) {
return null;
}
System.out.println(channelBuffer.readerIndex());
//mark the reader index
channelBuffer.markReaderIndex();
//extract the length bytes and convert to an int value
//**note: length value of the message is a decimal not hex
StringBuilder lengthBuilder = new StringBuilder("");
for (int ctr = 1; ctr < 5; ctr += 1) {
lengthBuilder.append(String.format("%02x",
channelBuffer.getByte(ctr)));
}
int length = Integer.parseInt(hexToASCII(lengthBuilder.toString()));
System.out.println("This is the length: " + length);
System.out.println("reader index: " + channelBuffer.readerIndex());
channelBuffer.readerIndex(4);
//get the remaining bytes
if (channelBuffer.readableBytes() <= length) {
channelBuffer.resetReaderIndex();
return null;
}
String s = "";
for (int ctr = 0; ctr < length + 5; ctr += 1) {
s += (char) channelBuffer.getByte(ctr);
}
return s;
}
一切顺利,直到上int length = Integer.parseInt(hexToASCII(lengthBuilder.toString()));
线。在那一行之后,解码器仍然可以读取剩余的字节,但它现在使用实际消息作为长度字段,生成解析异常错误。
说,我有一条消息B0005EHELLO
,其中[B is the header] [0005 - actual message length] [E - header 2] [HELLO - actual message]
..将长度字段解析为整数值后,解码器使用实际消息的前四个字母HELL
来解析长度字段,并产生异常。请帮我解决这个问题。