在Markdown中用mermaid语法绘制图表

时序图

时序图用于描述对象之间的传递消息的时间顺序, 即用例中的行为顺序. 顺序图稍微复杂了一丢丢，代码如下

```mermaid
sequenceDiagram
    participant Alice
    participant Bob
    participant John
    
    Alice->>John: Hello John, how are you?
    
    loop Healthcheck
        John->>John: Fight against hypochondria
    end
    
    Note right of John: Rational thoughts <br/>prevail!
    John-->>Alice: Great!
    John->>Bob: How about you?
    Bob-->>John: Jolly good!
```

用到的关键词

状态图

通过建立对象的生存周期模型来描述对象随时间变化的动态行为

代码

```mermaid
stateDiagram 
    Start --> First
    First --> Second
    First --> Third
    Second --> End
    Third --> End

    state First {
        [*] --> fir
        fir --> [*]
    }
    state Second {
        [*] --> sec
        sec --> [*]
    }
    state Third {}
```

代码关键词解读

我们可以看到状态state还可以定义内部的流程，如First和Second；Third没有定义内部处理过程。

甘特图

代码如下

```mermaid
gantt
dateFormat  YYYY-MM-DD
title Adding GANTT diagram to mermaid
excludes weekdays 2014-01-10

section A section
Completed task            :done,    des1, 2014-01-06,2014-01-08
Active task               :active,  des2, 2014-01-09, 3d
Future task               :         des3, after des2, 5d
Future task2               :         des4, after des3, 5d
```

用到的关键词

```mermaid
classDiagram
      Animal <|-- Duck
      Animal <|-- Fish
      Animal <|-- Zebra
      Animal : int age
      Animal : String gender
      Animal: isMammal()
      Animal: mate()
      class Duck{
          String beakColor
          swim()
          quack()
      }
      class Fish{
          int sizeInFeet
          canEat()
      }
      class Zebra{
          bool is_wild
          run()
          eat()
      }
```