擅长:python、mysql、java
<p>是的,默认值为0。在<a href="https://developers.google.com/protocol-buffers/docs/proto3#default" rel="noreferrer">the documentation</a>中明确提到了这种情况:</p>
<blockquote>
<p>Note that for scalar message fields, once a message is parsed there's
no way of telling whether a field was explicitly set to the default
value (for example whether a boolean was set to false) or just not set
at all: you should bear this in mind when defining your message types.
For example, don't have a boolean that switches on some behaviour when
set to false if you don't want that behaviour to also happen by
default. Also note that if a scalar message field is set to its
default, the value will not be serialized on the wire.</p>
</blockquote>