前言

相信很多人都遇到过想在React项目中动态加载路由这种问题，接下来我们逐步实现。

引入必要的依赖

import React from 'react'
import { Router, Route, IndexRoute, hashHistory } from 'react-router'

接下来创建一个component函数

目的就是为了变为router的component实现异步加载。

// 异步按需加载component
function asyncComponent(getComponent) {
    return class AsyncComponent extends React.Component {
      static Component = null;
      state = { Component: AsyncComponent.Component };
  
      componentDidMount() {
        if (!this.state.Component) {
          getComponent().then(({default: Component}) => {
            AsyncComponent.Component = Component
            this.setState({ Component })
          })
        }
      }
      //组件将被卸载  
    componentWillUnmount(){ 
        //重写组件的setState方法，直接返回空
        this.setState = (state,callback)=>{
            return;
        };  
    }
      render() {
        const { Component } = this.state
        if (Component) {
          return <Component {...this.props} />
        }
        return null
      }
    }
  }

在此说明componentWillUnmount钩子是为了解决Can only update a mounted or mounting component的这个问题，原因是当离开页面以后，组件已经被卸载，执行setState时无法找到渲染组件。

接下来实现本地文件路径的传入

 function load(component) {
    return import(`./routes/${component}`)
  }

将已知地址路径传递到一个函数并把这个函数作为参数传递到 asyncComponent中这样asyncComponent就能接收到这个路由的地址了，然后我们要做的就是将这个asyncComponent函数带入到router中。

<Router history={hashHistory}>
        <Route name="home" breadcrumbName="首页" path="/" component={MainLayout}>
            <IndexRoute name="undefined" breadcrumbName="未定义" component={() => <div>未定义</div>}/>
            <Route name="Development" breadcrumbName="施工中" path="Development" component={DevelopmentPage}/>
            <Route breadcrumbName="个人助理" path="CustomerWorkTodo" component={({children}) => <div className="box">{children}</div>}>
                <Route name="Agency" breadcrumbName="待办事项" path="Agency" component={asyncComponent(() => load('GlobalNotification/CustomerWorkAssistantTodo/CustomerAgencyMatter'))}/>
                <Route name="Already" breadcrumbName="已办事项" path="Already" component={asyncComponent(() => load('GlobalNotification/CustomerWorkAssistantTodo/CustomerAlreadyMatter'))}/>
                <Route name="SystemMessage" breadcrumbName="系统消息" path="SystemMessage/:data" component={asyncComponent(() => load('GlobalNotification/SystemMessage/SystemMessage'))}/>
                <Route name="SystemMessagePer" breadcrumbName="系统消息详情" path="SystemMessagePer/:data" component={asyncComponent(() => load('GlobalNotification/SystemMessage/SystemMessagePer'))}/>
            </Route>
        </Router>
 </Router>       

从代码中可以看出已经实现了router 的component 的引入，这样自然就可以通过一个循环来实现动态的加载啦！