高阶组件（Higher-Order Component，HOC）是一种用于在 React 中复用组件逻辑的技术。以下是几个常见的 HOC 使用案例，以及详细的代码示例。

1. 日志记录 HOC

这个高阶组件将在每次组件更新时记录日志。

LoggingHOC.js

import React from 'react';  const withLogging = (WrappedComponent) => {   return class extends React.Component {     componentDidMount() {       console.log(`${WrappedComponent.name} mounted`);     }      componentDidUpdate() {       console.log(`${WrappedComponent.name} updated`);     }      componentWillUnmount() {       console.log(`${WrappedComponent.name} will unmount`);     }      render() {       return ...this.props} />;     }   }; };  export default withLogging; 

使用日志记录 HOC

// src/App.js import React from 'react'; import withLogging from './LoggingHOC';  const MyComponent = () => {   return 
My Component
; };  const LoggedMyComponent = withLogging(MyComponent);  const App = () => {   return (     
            
   ); };  export default App; 

2. 数据获取 HOC

这个高阶组件在组件挂载时从一个 API 获取数据，并将数据传递给被包装的组件。

FetchDataHOC.js

import React from 'react';  const withFetchData = (url) => (WrappedComponent) => {   return class extends React.Component {     state = {       data: null,       loading: true,       error: null,     };      async componentDidMount() {       try {         const response = await fetch(url);         const data = await response.json();         this.setState({ data, loading: false });       } catch (error) {         this.setState({ error, loading: false });       }     }      render() {       const { data, loading, error } = this.state;       return data} loading={loading} error={error} {...this.props} />;     }   }; };  export default withFetchData; 

使用数据获取 HOC

// src/App.js import React from 'react'; import withFetchData from './FetchDataHOC';  const DataComponent = ({ data, loading, error }) => {   if (loading) return 
Loading...
;   if (error) return 
Error: {error.message}
;   return 
Data: {JSON.stringify(data)}
; };  const FetchDataComponent = withFetchData('https://api.example.com/data')(DataComponent);  const App = () => {   return (     
            
   ); };  export default App; 

3. 权限控制 HOC

这个高阶组件根据用户权限来控制组件的渲染。

withAuthorization.js

import React from 'react';  const withAuthorization = (requiredRole) => (WrappedComponent) => {   return class extends React.Component {     render() {       const { user } = this.props;       if (user.role !== requiredRole) {         return 
You do not have permission to view this page
;       }       return ...this.props} />;     }   }; };  export default withAuthorization; 

使用权限控制 HOC

// src/App.js import React from 'react'; import withAuthorization from './withAuthorization';  const AdminPage = () => {   return 
Admin Page
; };  const AuthorizedAdminPage = withAuthorization('admin')(AdminPage);  const App = () => {   const user = { role: 'user' }; // change to 'admin' to see the page   return (     
       user} />     
   ); };  export default App; 

4. 动态样式 HOC

这个高阶组件根据 props 动态添加样式。

withDynamicStyles.js

import React from 'react';  const withDynamicStyles = (WrappedComponent) => {   return class extends React.Component {     render() {       const style = {         color: this.props.color || 'black',         fontSize: this.props.fontSize || '16px',       };       return ...this.props} style={style} />;     }   }; };  export default withDynamicStyles; 

使用动态样式 HOC

// src/App.js import React from 'react'; import withDynamicStyles from './withDynamicStyles';  const StyledComponent = ({ style }) => {   return 
style}>Styled Component
; };  const DynamicStyledComponent = withDynamicStyles(StyledComponent);  const App = () => {   return (     
            
   ); };  export default App; 

总结

高阶组件是一种强大的模式，可以在 React 中实现代码复用和逻辑抽象。通过高阶组件，你可以：

• 提取和重用跨组件的逻辑
• 控制组件的渲染
• 操作传递给组件的 props
• 管理和注入状态