startConnect 静态方法
实现
static Future<ConnectionTask<Socket>> startConnect(host, int port,
{sourceAddress, int sourcePort = 0}) {
final IOOverrides? overrides = IOOverrides.current;
if (overrides == null) {
return Socket._startConnect(host, port,
sourceAddress: sourceAddress, sourcePort: sourcePort);
}
return overrides.socketStartConnect(host, port,
sourceAddress: sourceAddress, sourcePort: sourcePort);
}