Unity2019.3API教程（四）Component类

Component类

1. 官方定义
class in UnityEngine/Inherits from:Object/Implemented in:UnityEngine.CoreModule
属于UnityEngine命名空间下，继承自Object类，与之前的Object类和GameObject类一样属于核心模块。

2. 官方描述
Base class for everything attached to GameObjects.
Note that your code will never directly create a Component. Instead, you write script code, and attach the script to a GameObject. See Also: ScriptableObject as a way to create scripts that do not attach to any GameObject.
此类要对比下GameObject类，GameObject类是场景中所有实体的基类，而Component类是挂载在实体身上所有组件的基类，官方强调脚本是一个组件，但是脚本不可以直接挂载到实体上，当然官方介绍的ScriptableObject类是一种不附加到实体上的方法，后续再做介绍。

3. 属性
gameObject：The game object this component is attached to. A component is always attached to a gameobject.
语法：public GameObject gameObject;
获取自身物体，Component类比较特殊，除了gameobject这个属性，其他的与GameObject类的属性和方法相同，我这边全部裂解液出来，再在最后说明原因。

tag：The tag of this game object.

transform：The Transform attached to this GameObject.

4. 共有方法
BroadcastMessage：Calls the method named methodName on every MonoBehaviour in this game object or any of its children.

CompareTag：Is this game object tagged with tag ?

GetComponent：Returns the component of Type type if the game object has one attached, null if it doesn’t.

GetComponentInChildren：Returns the component of Type type in the GameObject or any of its children using depth first search.

GetComponentInParent：Returns the component of Type type in the GameObject or any of its parents.

GetComponents：Returns all components of Type type in the GameObject.

GetComponentsInChildren：Returns all components of Type type in the GameObject or any of its children.

GetComponentsInParent：Returns all components of Type type in the GameObject or any of its parents.

SendMessage：Calls the method named methodName on every MonoBehaviour in this game object.

SendMessageUpwards：Calls the method named methodName on every MonoBehaviour in this game object and on every ancestor of the behaviour.

TryGetComponent：Gets the component of the specified type, if it exists.

以上就是官方2019.3版本Component类的全部内容，看过第三期教程的朋友会发现属性和方法和GameObject类基本相同，这是为什么呢，因为Unity在设计时，通过GameObject类创建场景实体，而实体的属性和功能通过组件来完成，而组件时挂载在实体上的，所以Component类给出gameobject属性（注意此处为小写），gameobject时Component类的属性，很多朋友在学习API时对于Object，GameObject以及gameobject发生混淆，Object和GameObject时类，具有父子关系，他们同属于UnityEngine命名空间下，而gameobject属于Component类的一个属性，Component类和Object也是一种父子关系，Component类和GameObject类在设计上属于同级关系，但是基于Unity的设计，在实现上，GameObjec类是实现的基础，而Component类是实现的行为外观，这里还要提一个Object类，根据Unity结构，他不属于UnityEngine命名空间下，而是System.Object，属于最终基类，因为我们用UNity写的脚本现在都是C#语言，这里只做概述不做具体介绍。所以，我们可以通过组件访问挂载物体，从而实现访问，示例如下：

using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{
    
    void Start()
    {
        GameObject go = new GameObject();
        go.AddComponent(typeof(Rigidbody));
        Rigidbody rg = go.GetComponent(typeof(Rigidbody))as Rigidbody;
        rg.gameObject.AddComponent(typeof(Mesh));
    }
}

后面官方给的是继承的内容，此处不做概述，本期教程到此结束，欢迎大家在评论区给出意见和指正，谢谢浏览。