proto3 scalar 标量

Scalar Value Types

.proto Type	Go Type	PHP Type
double	float64	float
float	float32	float
int32	int32	integer
int64	int64	integer/string
unit32	uint32	integer
unit64	uint64	integer/string
sint32	int32	integer
sint64	int64	integer/string
fixed32	unit32	integer
fixed64	unit64	integer/string
sfixed32	int32	integer
sfixed64	int64	integer/string
bool	bool	boolean
string	string	string
bytes	[]byte	string