@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    throw new Exception("throw Exception");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    System.out.println(cause.getMessage());
}

private void invokeChannelRead(Object msg) {
    if (invokeHandler()) {
        try {
            //調(diào)用了當(dāng)前handler的channelRead方法, 其實(shí)就是head對(duì)象調(diào)用自身的channelRead方法
            ((ChannelInboundHandler) handler()).channelRead(this, msg);
        } catch (Throwable t) {
            //發(fā)生異常的時(shí)候在這里捕獲異常
            notifyHandlerException(t);
        }
    } else {
        fireChannelRead(msg);
    }
}

private void notifyHandlerException(Throwable cause) {
    //代碼省略
    invokeExceptionCaught(cause);
}

private void invokeExceptionCaught(final Throwable cause) {
    if (invokeHandler()) {
        try {
            //當(dāng)前handler調(diào)用exceptionCaught()方法
            handler().exceptionCaught(this, cause);
        } catch (Throwable error) {
            //代碼省略
        }
    } else {
        fireExceptionCaught(cause);
    }
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    System.out.println(cause.getMessage());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    //寫(xiě)法1
    ctx.fireChannelRead(cause);
    //寫(xiě)法2
    ctx.pipeline().fireExceptionCaught(cause);
}

public final ChannelPipeline fireExceptionCaught(Throwable cause) {
    AbstractChannelHandlerContext.invokeExceptionCaught(head, cause);
    return this;
}

static void invokeExceptionCaught(final AbstractChannelHandlerContext next, final Throwable cause) {
    ObjectUtil.checkNotNull(cause, "cause");
    EventExecutor executor = next.executor();
    if (executor.inEventLoop()) {
        //執(zhí)行下一個(gè)節(jié)點(diǎn)的異常方法
        next.invokeExceptionCaught(cause);
    } else {
        try {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    next.invokeExceptionCaught(cause);
                }
            });
        } catch (Throwable t) {
            //忽略代碼
        }
    }
}

private void invokeExceptionCaught(final Throwable cause) {
    if (invokeHandler()) {
        try {
            //當(dāng)前handler調(diào)用exceptionCaught()方法
            handler().exceptionCaught(this, cause);
        } catch (Throwable error) {
            //代碼省略
        }
    } else {
        fireExceptionCaught(cause);
    }
}

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    ctx.fireExceptionCaught(cause);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    //寫(xiě)法1
    ctx.fireChannelRead(cause);
    //寫(xiě)法2
    ctx.pipeline().fireExceptionCaught(cause);
}

public ChannelHandlerContext fireExceptionCaught(final Throwable cause) {
    //傳播異常事件的時(shí)候, 直接拿了當(dāng)前節(jié)點(diǎn)的下一個(gè)節(jié)點(diǎn)
    invokeExceptionCaught(next, cause);
    return this;
}

static void invokeExceptionCaught(final AbstractChannelHandlerContext next, final Throwable cause) {
    ObjectUtil.checkNotNull(cause, "cause");
    EventExecutor executor = next.executor();
    if (executor.inEventLoop()) { 
        next.invokeExceptionCaught(cause);
    } else {
        try {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    next.invokeExceptionCaught(cause);
                }
            });
        } catch (Throwable t) {
            //代碼省略
        }
    }
}

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
        throws Exception {
    ctx.fireExceptionCaught(cause);
}

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    onUnhandledInboundException(cause);
}