Force Unity to serialize a private field.

　　强制Unity序列化一个私有变量。

　　You will almost never need this. When Unity serializes your scripts, it will only serialize public fields. If in addition to that you also want Unity to serialize one of your private fields you can add the SerializeField attribute to the field.

　　Unity will serialize all your script components, reload the new assemblies, and recreate your script components from the serialized verions. This serialization does not happen with .NET‘s serialization functionality, but with an internal Unity one.

　　The serialization system used can do the following:

　　- CAN serialize public nonstatic fields (of serializable types)
　　- CAN serialize nonpublic nonstatic fields marked with the [SerializeField] attribute.
　　- CANNOT serialize static fields.
　　- CANNOT serialize properties.

　　Your field will only serialize if it is of a type that Unity can serialize:

Serializable types are:

- All classes inheriting from UnityEngine.Object, for example GameObject, Component, MonoBehaviour, Texture2D, AnimationClip.. - All basic data types like int, string, float, bool. - Some built-in types like Vector2, Vector3, Vector4, Quaternion, Matrix4x4, Color, Rect, LayerMask.. - Arrays of a serializable type
- List of a serializable type (new in Unity2.6)
- Enums

Headsup note: if you put one element in a list (or array) twice, when the list gets serialized, you‘ll get two copies of that element, instead of one copy being in the new list twice.

Hint: Unity won‘t serialize Dictionary, however you could store a List<> for keys and a List<> for values, and sew them up in a non serialized dictionary on Awake(). This doesn‘t solve the problem of when you want to modify the dictionary and have it "saved" back, but it is a handy trick in a lot of other cases.

For UnityScript users: Fields in c# is a script variable in UnityScript, and [SerializeField] becomes @SerializeField. [Serializable] on a class becomes @script Serializable in a UnityScript.

参考：file://localhost/Applications/Unity/Unity.app/Contents/Documentation/html/en/ScriptReference/SerializeField.html　　

 【System.Serializable】

　　当一个成员是复合类型时，只要在这个复合类型上标注了[System.Serializable]属性，那这个成员也是一个可编辑的成员。Inspector窗口会按树的形式，依次罗列这个类型中的可编辑成员。