如何从YAML文件中排除类？

Question

I use SnakeYAML to persist data into YAML file.

DumperOptions options = new DumperOptions();
options.setPrettyFlow(true);
options.setAllowReadOnlyProperties(true);
Yaml yml = new Yaml(options);

FileWriter writer = new FileWriter(path);
yml.dump(object, writer);
writer.flush();
writer.close();

When I try to save the result, I get such content

!!com.test.yml.User
users:
- {
  name: Bob,
  age: 14
}
- {
  name: John,
  age: 15
}

How can I avoid class !!com.test.yml.User from the file?

Also I don't want to save null entities. For instance

- {
    name: null,
    age: 14
  }

should be

- {
    age: 14
  }

Answer 1

Representer representer = new Representer();
representer.addClassTag(com.test.yml.User.class, Tag.MAP);
Yaml yaml = new Yaml(representer);

This code says - please use Tag.MAP for the custom class User. Since the MAP tag is implicit, the tag will disappear all together. But to parse it back you have to instruct SnakeYAML how to parse the data into User instance.