在Netty 4中,如何捕获所有处理程序的未处理异常？

Question

在我的渠道管道中,有许多处理程序.

据我所知,如果我不覆盖他们的exceptionCaught(ChannelHandlerContext ctx, Throwable cause)方法,默​​认行为是cause将被抛出到管道,这样的东西将由管道记录在WARN级别:

An exception was thrown by a user handler's exceptionCaught() method while handling the following exception: ...

我想覆盖上面的管道行为来添加一些特定的逻辑(例如:如果cause是java.io.IOException: Connection reset by peer,不记录任何东西以避免太多"不太有用"的WARN级别的日志).

我该怎么办？

经过一番调查,我找到了这个源代码:https: //github.com/netty/netty/blob/4.0/transport/src/main/java/io/netty/channel/DefaultChannelHandlerContext.java

private void invokeExceptionCaught(final Throwable cause) {
    try {
        handler.exceptionCaught(this, cause);
    } catch (Throwable t) {
        if (logger.isWarnEnabled()) {
            logger.warn(
                    "An exception was thrown by a user handler's " +
                    "exceptionCaught() method while handling the following exception:", cause);
        }
    }
}

因为它是private,我不认为我可以轻易地覆盖它而不使用反射.有没有更好的办法？

Answer 1

您可以通过定义a ExceptionHandler然后将此处理程序放在管道的尾部来完成此操作.

ChannelPipeline p = ch.pipeline();
p.addLast("business", new SomeBusinessHandler());
p.addLast...
p.addLast("exception", new ExceptionHandler());//Make sure this is the last line when init the pipeline.

并在exceptionCaught方法中编写您的特定逻辑.但永远不要重新抛出异常,因为这是管道的终结.