mina,TextLineDecoder

最新推荐文章于 2021-08-10 23:30:01 发布

最新推荐文章于 2021-08-10 23:30:01 发布 · 288 阅读

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#java

本文介绍了一个解决Mina框架中TextLineDecoder在特定情况下导致客户端等待的方法。通过继承TextLineDecoder并覆盖decode方法，在接收的数据末尾强制添加'/n'来确保消息能够被正确解析。

使用mina的TextLineDecoder，可以指定接收数据的结束符号，但如果没有指定结束符，就默认会去匹配'/n'或者'/r'结束符

如果从服务端返回的数据没有包含这些结束符，客户端就会等待。

为了不让客户端等待下去，可以增加一个TextLineDecoder子类，如下：

public class ClientTextLineDecoder extends TextLineDecoder {

@Override
public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out)
throws Exception {

/*--------在当前buffer后面追加一个'/n' -------*/

in.setAutoExpand(true);//设置自动扩展
in.position(in.limit());
in.put((byte)'/n');
in.position(0);

super.decode(session, in, out);
}

}

我们只要在调用父类的decode方法之前在buffer后面追加一个'/n'结束符，就可以解决问题。

下面是buffer相关的知识：

Buffer foundations

The abstract Buffer class forms the foundation of the java.nio package's buffer support. Buffer works like an in-memory RandomAccessFile for reading and writing primitive data types. Like a RandomAccessFile , with Buffer the next operation you perform (read/write) happens at your position. Performing either operation changes that position, so doing a read after a write doesn't read what was just written, but what is after what was just written. Buffer offers four indicators for access to the linear structure (from highest value to lowest):

capacity() : Indicates the buffer's size
limit() : Tells you how many bytes you've stuffed into the buffer so far, or lets you change that limit with :limit(int newLimit) :
position() : Tells you the current location to perform the next read/write operation
mark() : Lets you remember a position for later resetting with reset()