var routes =  [   
  {
    name: '首页',
    showHead: true,
    path: '/',
    component: index
  },
  {
    name: '详情',
    showHead: false,
    path: '/book',
    component: book
  }
]

class App extends Component {
  render() {
    return (
        <Router>
            <div>
              {
                routes.map((item,index)=>{
                   return <Route key={item.name} path={item.path} render={()=>(<item.component/>)}/>
                })
              }
              <header></header>
            </div>
        </Router>
    );
  }
}

在根组件中有一个header组件，切换路由的时候如何根据数组中showHead字段控制头部的显示与隐藏