{"id":1419,"date":"2024-06-02T23:05:00","date_gmt":"2024-06-02T23:05:00","guid":{"rendered":""},"modified":"2024-06-05T06:12:46","modified_gmt":"2024-06-04T22:12:46","slug":"react-%e4%b9%8b-context-%e7%9a%84%e5%8f%98%e8%bf%81%e4%b8%8e%e8%83%8c%e5%90%8e%e5%ae%9e%e7%8e%b0","status":"publish","type":"post","link":"https:\/\/www.lccc.top\/?p=1419","title":{"rendered":"React \u4e4b Context \u7684\u53d8\u8fc1\u4e0e\u80cc\u540e\u5b9e\u73b0"},"content":{"rendered":"\n

Context<\/h2>\n

\u672c\u7bc7\u6211\u4eec\u8bb2 Context\uff0cContext \u53ef\u4ee5\u5b9e\u73b0\u8de8\u7ec4\u4ef6\u4f20\u9012\u6570\u636e\uff0c\u5927\u90e8\u5206\u7684\u65f6\u5019\u5e76\u65e0\u9700\u8981\uff0c\u4f46\u6709\u7684\u65f6\u5019\uff0c\u6bd4\u5982\u7528\u6237\u8bbe\u7f6e \u4e86 UI \u4e3b\u9898\u3001\u5730\u533a\u504f\u597d\uff0c\u5982\u679c\u4ece\u9876\u5c42\u4e00\u5c42\u5c42\u5f80\u4e0b\u4f20\u53cd\u800c\u6709\u4e9b\u9ebb\u70e6\uff0c\u4e0d\u5982\u76f4\u63a5\u501f\u52a9 Context \u5b9e\u73b0\u6570\u636e\u4f20\u9012\u3002<\/p>\n

\u8001\u7684 Context API<\/h2>\n

\u57fa\u7840\u793a\u4f8b<\/h3>\n

\u5728\u8bb2\u6700\u65b0\u7684 API \u524d\uff0c\u6211\u4eec\u5148\u56de\u987e\u4e0b\u8001\u7684 Context API\uff1a<\/p>\n

<\/p>\n
class<\/span> Child<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    \/\/ 4. \u8fd9\u91cc\u4f7f\u7528 this.context.value \u83b7\u53d6<\/span>\n    return<\/span> <<\/span>p<\/span>><\/span>{<\/span>this<\/span>.<\/span>context<\/span>.<\/span>value<\/span>}<\/span><<\/span>\/<\/span>p<\/span>><\/span>\n  }<\/span>\n}<\/span>\n\n\/\/ 3. \u5b50\u7ec4\u4ef6\u6dfb\u52a0 contextTypes \u9759\u6001\u5c5e\u6027<\/span>\nChild<\/span>.<\/span>contextTypes<\/span> =<\/span> {<\/span>\n  value<\/span>: PropTypes<\/span>.<\/span>string<\/span>\n}<\/span>;<\/span>\n\nclass<\/span> Parent<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n\n  state<\/span> =<\/span> {<\/span>\n    value<\/span>: 'foo'<\/span>\n  }<\/span>\n\n  \/\/ 1. \u5f53 state \u6216\u8005 props \u6539\u53d8\u7684\u65f6\u5019\uff0cgetChildContext \u51fd\u6570\u5c31\u4f1a\u88ab\u8c03\u7528<\/span>\n  getChildContext<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> {<\/span>value<\/span>: this<\/span>.<\/span>state<\/span>.<\/span>value<\/span>}<\/span>\n  }<\/span>\n\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> (<\/span>\n      <<\/span>div<\/span>><\/span>\n        <<\/span>Child<\/span> \/<\/span>><\/span>\n      <<\/span>\/<\/span>div<\/span>><\/span>\n    )<\/span>\n  }<\/span>\n}<\/span>\n\n\/\/ 2. \u7236\u7ec4\u4ef6\u6dfb\u52a0 childContextTypes \u9759\u6001\u5c5e\u6027<\/span>\nParent<\/span>.<\/span>childContextTypes<\/span> =<\/span> {<\/span>\n  value<\/span>: PropTypes<\/span>.<\/span>string<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
context \u4e2d\u65ad\u95ee\u9898<\/h3>\n
\u5bf9\u4e8e\u8fd9\u4e2a API\uff0cReact \u5b98\u65b9\u5e76\u4e0d\u5efa\u8bae\u4f7f\u7528\uff0c\u5bf9\u4e8e\u53ef\u80fd\u4f1a\u51fa\u73b0\u7684\u95ee\u9898\uff0cReact \u6587\u6863\u7ed9\u51fa\u7684\u4ecb\u7ecd\u4e3a\uff1a<\/p>\n
\n
\u95ee\u9898\u662f\uff0c\u5982\u679c\u7ec4\u4ef6\u63d0\u4f9b\u7684\u4e00\u4e2a context \u53d1\u751f\u4e86\u53d8\u5316\uff0c\u800c\u4e2d\u95f4\u7236\u7ec4\u4ef6\u7684 shouldComponentUpdate \u8fd4\u56de false\uff0c\u90a3\u4e48\u4f7f\u7528\u5230\u8be5\u503c\u7684\u540e\u4ee3\u7ec4\u4ef6\u4e0d\u4f1a\u8fdb\u884c\u66f4\u65b0\u3002\u4f7f\u7528\u4e86 context \u7684\u7ec4\u4ef6\u5219\u5b8c\u5168\u5931\u63a7\uff0c\u6240\u4ee5\u57fa\u672c\u4e0a\u6ca1\u6709\u529e\u6cd5\u80fd\u591f\u53ef\u9760\u7684\u66f4\u65b0 context\u3002<\/p>\n<\/blockquote>\n
\u5bf9\u4e8e\u8fd9\u4e2a\u95ee\u9898\uff0c\u6211\u4eec\u5199\u4e2a\u793a\u4f8b\u4ee3\u7801\uff1a<\/p>\n
<\/p>\n
\/\/ 1. Child \u7ec4\u4ef6\u4f7f\u7528 PureComponent<\/span>\nclass<\/span> Child<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> <<\/span>GrandChild<\/span> \/<\/span>><\/span>\n  }<\/span>\n}<\/span>\n\nclass<\/span> GrandChild<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> <<\/span>p<\/span>><\/span>{<\/span>this<\/span>.<\/span>context<\/span>.<\/span>theme<\/span>}<\/span><<\/span>\/<\/span>p<\/span>><\/span>\n  }<\/span>\n}<\/span>\n\nGrandChild<\/span>.<\/span>contextTypes<\/span> =<\/span> {<\/span>\n  theme<\/span>: PropTypes<\/span>.<\/span>string<\/span>\n}<\/span>;<\/span>\n\nclass<\/span> Parent<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n\n  state<\/span> =<\/span> {<\/span>\n    theme<\/span>: 'red'<\/span>\n  }<\/span>\n\n  getChildContext<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> {<\/span>theme<\/span>: this<\/span>.<\/span>state<\/span>.<\/span>theme<\/span>}<\/span>\n  }<\/span>\n\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> (<\/span>\n      <<\/span>div<\/span> onClick<\/span>=<\/span>{<\/span>(<\/span>)<\/span> =><\/span> {<\/span>\n        this<\/span>.<\/span>setState<\/span>(<\/span>{<\/span>\n          theme<\/span>: 'blue'<\/span>\n        }<\/span>)<\/span>\n      }<\/span>}<\/span>><\/span>\n        <<\/span>Child<\/span> \/<\/span>><\/span>\n        <<\/span>Child<\/span> \/<\/span>><\/span>\n      <<\/span>\/<\/span>div<\/span>><\/span>\n    )<\/span>\n  }<\/span>\n}<\/span>\n\nParent<\/span>.<\/span>childContextTypes<\/span> =<\/span> {<\/span>\n  theme<\/span>: PropTypes<\/span>.<\/span>string<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
\u5728\u8fd9\u4e2a\u793a\u4f8b\u4ee3\u7801\u4e2d\uff0c\u5f53\u70b9\u51fb\u6587\u5b57 red<\/code> \u7684\u65f6\u5019\uff0c\u6587\u5b57\u5e76\u4e0d\u4f1a\u4fee\u6539\u4e3a blue<\/code>\uff0c\u5982\u679c\u6211\u4eec\u628a Child \u6539\u4e3a extends Component<\/code>\uff0c\u5219\u80fd\u6b63\u5e38\u4fee\u6539<\/p>\n
\u8fd9\u8bf4\u660e\u5f53\u4e2d\u95f4\u7ec4\u4ef6\u7684 shouldComponentUpdate<\/code> \u4e3a false<\/code> \u65f6\uff0c\u4f1a\u4e2d\u65ad  Context \u7684\u4f20\u9012\u3002<\/p>\n
PureComponent \u7684\u5b58\u5728\u662f\u4e3a\u4e86\u51cf\u5c11\u4e0d\u5fc5\u8981\u7684\u6e32\u67d3\uff0c\u4f46\u6211\u4eec\u53c8\u60f3 Context \u80fd\u6b63\u5e38\u4f20\u9012\uff0c\u54ea\u6709\u529e\u6cd5\u53ef\u4ee5\u89e3\u51b3\u5417\uff1f<\/p>\n
\u65e2\u7136 PureComponent \u7684\u5b58\u5728\u5bfc\u81f4\u4e86 Context \u65e0\u6cd5\u518d\u66f4\u65b0\uff0c\u90a3\u5c31\u5e72\u8106\u4e0d\u66f4\u65b0\u4e86\uff0cContext \u4e0d\u66f4\u65b0\uff0cGrandChild \u5c31\u65e0\u6cd5\u66f4\u65b0\u5417\uff1f<\/p>\n
\u89e3\u51b3\u65b9\u6848<\/h3>\n
\u65b9\u6cd5\u5f53\u7136\u662f\u6709\u7684\uff1a<\/p>\n
<\/p>\n
\/\/ 1. \u5efa\u7acb\u4e00\u4e2a\u8ba2\u9605\u53d1\u5e03\u5668\uff0c\u5f53\u7136\u4f60\u4e5f\u53ef\u4ee5\u79f0\u547c\u5b83\u4e3a\u4f9d\u8d56\u6ce8\u5165\u7cfb\u7edf\uff08dependency injection system\uff09\uff0c\u7b80\u79f0 DI<\/span>\nclass<\/span> Theme<\/span> {<\/span>\n  constructor<\/span>(<\/span>value<\/span>)<\/span> {<\/span>\n    this<\/span>.<\/span>value<\/span> =<\/span> value<\/span>\n    this<\/span>.<\/span>subscriptions<\/span> =<\/span> [<\/span>]<\/span>\n  }<\/span>\n\n  setValue<\/span>(<\/span>value<\/span>)<\/span> {<\/span>\n    this<\/span>.<\/span>value<\/span> =<\/span> value<\/span>\n    this<\/span>.<\/span>subscriptions<\/span>.<\/span>forEach<\/span>(<\/span>f<\/span> =><\/span> f<\/span>(<\/span>)<\/span>)<\/span>\n  }<\/span>\n\n  subscribe<\/span>(<\/span>f<\/span>)<\/span> {<\/span>\n    this<\/span>.<\/span>subscriptions<\/span>.<\/span>push<\/span>(<\/span>f<\/span>)<\/span>\n  }<\/span>\n}<\/span>\n\n\nclass<\/span> Child<\/span> extends<\/span> React<\/span>.<\/span>PureComponent<\/span> {<\/span>\n    render<\/span>(<\/span>)<\/span> {<\/span>\n        return<\/span> <<\/span>GrandChild<\/span> \/<\/span>><\/span>\n    }<\/span>\n}<\/span>\n\n\nclass<\/span> GrandChild<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n    componentDidMount<\/span>(<\/span>)<\/span> {<\/span>\n      \/\/ 4. GrandChild \u83b7\u53d6 store \u540e\uff0c\u8fdb\u884c\u8ba2\u9605<\/span>\n        this<\/span>.<\/span>context<\/span>.<\/span>theme<\/span>.<\/span>subscribe<\/span>(<\/span>(<\/span>)<\/span> =><\/span> this<\/span>.<\/span>forceUpdate<\/span>(<\/span>)<\/span>)<\/span>\n    }<\/span>\n\n    \/\/ 5. GrandChild \u4ece store \u4e2d\u83b7\u53d6\u6240\u9700\u8981\u7684\u503c<\/span>\n    render<\/span>(<\/span>)<\/span> {<\/span>\n        return<\/span> <<\/span>p<\/span>><\/span>{<\/span>this<\/span>.<\/span>context<\/span>.<\/span>theme<\/span>.<\/span>value<\/span>}<\/span><<\/span>\/<\/span>p<\/span>><\/span>\n    }<\/span>\n}<\/span>\n\nGrandChild<\/span>.<\/span>contextTypes<\/span> =<\/span> {<\/span>\n  theme<\/span>: PropTypes<\/span>.<\/span>object<\/span>\n}<\/span>;<\/span>\n\nclass<\/span> Parent<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n    constructor<\/span>(<\/span>p<\/span>,<\/span> c<\/span>)<\/span> {<\/span>\n      super<\/span>(<\/span>p<\/span>,<\/span> c<\/span>)<\/span>\n      \/\/ 2. \u6211\u4eec\u5b9e\u4f8b\u5316\u4e00\u4e2a store\uff08\u60f3\u60f3 redux \u7684 store\uff09\uff0c\u5e76\u5b58\u5230\u5b9e\u4f8b\u5c5e\u6027\u4e2d<\/span>\n      this<\/span>.<\/span>theme<\/span> =<\/span> new<\/span> Theme<\/span>(<\/span>'blue'<\/span>)<\/span>\n    }<\/span>\n\n    \/\/ 3. \u901a\u8fc7 context \u4f20\u9012\u7ed9 GrandChild \u7ec4\u4ef6<\/span>\n    getChildContext<\/span>(<\/span>)<\/span> {<\/span>\n        return<\/span> {<\/span>theme<\/span>: this<\/span>.<\/span>theme<\/span>}<\/span>\n    }<\/span>\n\n    render<\/span>(<\/span>)<\/span> {<\/span>\n        \/\/ 6. \u901a\u8fc7 store \u8fdb\u884c\u53d1\u5e03<\/span>\n        return<\/span> (<\/span>\n            <<\/span>div<\/span> onClick<\/span>=<\/span>{<\/span>(<\/span>)<\/span> =><\/span> {<\/span>\n                this<\/span>.<\/span>theme<\/span>.<\/span>setValue<\/span>(<\/span>'red'<\/span>)<\/span>\n            }<\/span>}<\/span>><\/span>\n              <<\/span>Child<\/span> \/<\/span>><\/span>\n              <<\/span>Child<\/span> \/<\/span>><\/span>\n            <<\/span>\/<\/span>div<\/span>><\/span>\n        )<\/span>\n    }<\/span>\n}<\/span>\n\nParent<\/span>.<\/span>childContextTypes<\/span> =<\/span> {<\/span>\n  theme<\/span>: PropTypes<\/span>.<\/span>object<\/span>\n}<\/span>;<\/span><\/pre>\n<\/div>\n
\u4e3a\u4e86\u7ba1\u7406\u6211\u4eec\u7684 theme \uff0c\u6211\u4eec\u5efa\u7acb\u4e86\u4e00\u4e2a\u4f9d\u8d56\u6ce8\u5165\u7cfb\u7edf\uff08DI\uff09\uff0c\u5e76\u901a\u8fc7 Context \u5411\u4e0b\u4f20\u9012 store\uff0c\u9700\u8981\u7528\u5230 store \u6570\u636e\u7684\u7ec4\u4ef6\u8fdb\u884c\u8ba2\u9605\uff0c\u4f20\u5165\u4e00\u4e2a forceUpdate \u51fd\u6570\uff0c\u5f53 store \u8fdb\u884c\u53d1\u5e03\u7684\u65f6\u5019\uff0c\u4f9d\u8d56 theme \u7684\u5404\u4e2a\u7ec4\u4ef6\u6267\u884c forceUpdate\uff0c\u7531\u6b64\u5b9e\u73b0\u4e86\u5728 Context \u4e0d\u66f4\u65b0\u7684\u60c5\u51b5\u4e0b\u5b9e\u73b0\u4e86\u5404\u4e2a\u4f9d\u8d56\u7ec4\u4ef6\u7684\u66f4\u65b0\u3002<\/p>\n
\u4f60\u53ef\u80fd\u4e5f\u53d1\u73b0\u4e86\uff0c\u8fd9\u6709\u4e86\u4e00\u70b9 react-redux \u7684\u5473\u9053\u3002<\/p>\n
\u5f53\u7136\u6211\u4eec\u4e5f\u53ef\u4ee5\u501f\u52a9 Mobx \u6765\u5b9e\u73b0\u5e76\u7b80\u5316\u4ee3\u7801\uff0c\u5177\u4f53\u7684\u5b9e\u73b0\u53ef\u4ee5\u53c2\u8003 Michel Weststrate\uff08Mobx \u7684\u4f5c\u8005\uff09 \u7684 How to safely use React context<\/a><\/p>\n
\u65b0\u7684 Context API<\/h2>\n
\u57fa\u7840\u793a\u4f8b<\/h3>\n
\u60f3\u5fc5\u5927\u5bb6\u90fd\u6216\u591a\u6216\u5c11\u7684\u7528\u8fc7\uff0c\u6211\u4eec\u76f4\u63a5\u4e0a\u793a\u4f8b\u4ee3\u7801\uff1a<\/p>\n
<\/p>\n
\/\/ 1. \u521b\u5efa Provider \u548c Consumer<\/span>\nconst<\/span> {<\/span>Provider,<\/span> Consumer}<\/span> =<\/span> React<\/span>.<\/span>createContext<\/span>(<\/span>'dark'<\/span>)<\/span>;<\/span>\n\nclass<\/span> Child<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n  \/\/ 3. Consumer \u7ec4\u4ef6\u63a5\u6536\u4e00\u4e2a\u51fd\u6570\u4f5c\u4e3a\u5b50\u5143\u7d20\u3002\u8fd9\u4e2a\u51fd\u6570\u63a5\u6536\u5f53\u524d\u7684 context \u503c\uff0c\u5e76\u8fd4\u56de\u4e00\u4e2a React \u8282\u70b9\u3002<\/span>\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    return<\/span> (<\/span>\n      <<\/span>Consumer<\/span>><\/span>\n        {<\/span>(<\/span>theme<\/span>)<\/span> =><\/span> (<\/span>\n        <<\/span>button<\/span>><\/span>\n          {<\/span>theme<\/span>}<\/span>\n        <<\/span>\/<\/span>button<\/span>><\/span>\n      )<\/span>}<\/span>\n      <<\/span>\/<\/span>Consumer<\/span>><\/span>\n    )<\/span>\n  }<\/span>\n}<\/span>\n\nclass<\/span> Parent<\/span> extends<\/span> React<\/span>.<\/span>Component<\/span> {<\/span>\n\n  state<\/span> =<\/span> {<\/span>\n    theme<\/span>: 'dark'<\/span>,<\/span>\n  }<\/span>;<\/span>\n\n  componentDidMount<\/span>(<\/span>)<\/span> {<\/span>\n    setTimeout<\/span>(<\/span>(<\/span>)<\/span> =><\/span> {<\/span>\n      this<\/span>.<\/span>setState<\/span>(<\/span>{<\/span>\n        theme<\/span>: 'light'<\/span>\n      }<\/span>)<\/span>\n    }<\/span>,<\/span> 2000<\/span>)<\/span>\n  }<\/span>\n\n\n  render<\/span>(<\/span>)<\/span> {<\/span>\n    \/\/ 2. \u901a\u8fc7 Provider \u7684 value \u4f20\u9012\u503c<\/span>\n    return<\/span> (<\/span>\n      <<\/span>Provider<\/span> value<\/span>=<\/span>{<\/span>this<\/span>.<\/span>state<\/span>.<\/span>theme<\/span>}<\/span>><\/span>\n        <<\/span>Child<\/span> \/<\/span>><\/span>\n      <<\/span>\/<\/span>Provider<\/span>><\/span>\n    )<\/span>\n  }<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u5f53 Provider \u7684 value \u503c\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u5b83\u5185\u90e8\u7684\u6240\u6709 consumer \u7ec4\u4ef6\u90fd\u4f1a\u91cd\u65b0\u6e32\u67d3\u3002<\/p>\n
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\u65b0 API \u7684\u597d\u5904\u5c31\u5728\u4e8e\u4ece Provider \u5230\u5176\u5185\u90e8 consumer \u7ec4\u4ef6\uff08\u5305\u62ec .contextType \u548c useContext\uff09\u7684\u4f20\u64ad\u4e0d\u53d7\u5236\u4e8e shouldComponentUpdate \u51fd\u6570\uff0c\u56e0\u6b64\u5f53 consumer \u7ec4\u4ef6\u5728\u5176\u7956\u5148\u7ec4\u4ef6\u8df3\u8fc7\u66f4\u65b0\u7684\u60c5\u51b5\u4e0b\u4e5f\u80fd\u66f4\u65b0\u3002<\/p>\n<\/blockquote>\n
\u6a21\u62df\u5b9e\u73b0<\/h3>\n
\u90a3\u4e48 createContext \u662f\u600e\u4e48\u5b9e\u73b0\u7684\u5462\uff1f\u6211\u4eec\u5148\u4e0d\u770b\u6e90\u7801\uff0c\u6839\u636e\u524d\u9762\u7684\u8ba2\u9605\u53d1\u5e03\u5668\u7684\u7ecf\u9a8c\uff0c\u6211\u4eec\u81ea\u5df1\u5176\u5b9e\u5c31\u53ef\u4ee5\u5199\u51fa\u4e00\u4e2a createContext \u6765\uff0c\u6211\u4eec\u5199\u4e00\u4e2a\u8bd5\u8bd5\uff1a<\/p>\n
<\/p>\n
class<\/span> Store<\/span> {<\/span>\n    constructor<\/span>(<\/span>)<\/span> {<\/span>\n        this<\/span>.<\/span>subscriptions<\/span> =<\/span> [<\/span>]<\/span>\n    }<\/span>\n\n    publish<\/span>(<\/span>value<\/span>)<\/span> {<\/span>\n        this<\/span>.<\/span>subscriptions<\/span>.<\/span>forEach<\/span>(<\/span>f<\/span> =><\/span> f<\/span>(<\/span>value<\/span>)<\/span>)<\/span>\n    }<\/span>\n\n    subscribe<\/span>(<\/span>f<\/span>)<\/span> {<\/span>\n        this<\/span>.<\/span>subscriptions<\/span>.<\/span>push<\/span>(<\/span>f<\/span>)<\/span>\n    }<\/span>\n}<\/span>\n\nfunction<\/span> createContext<\/span>(<\/span>defaultValue<\/span>)<\/span> {<\/span>\n    const<\/span> store<\/span> =<\/span> new<\/span> Store<\/span>(<\/span>)<\/span>;<\/span>\n\n    \/\/ Provider<\/span>\n    class<\/span> Provider<\/span> extends<\/span> React<\/span>.<\/span>PureComponent<\/span> {<\/span>\n        componentDidUpdate<\/span>(<\/span>)<\/span> {<\/span>\n            store<\/span>.<\/span>publish<\/span>(<\/span>this<\/span>.<\/span>props<\/span>.<\/span>value<\/span>)<\/span>;<\/span>\n        }<\/span>\n\n        componentDidMount<\/span>(<\/span>)<\/span> {<\/span>\n            store<\/span>.<\/span>publish<\/span>(<\/span>this<\/span>.<\/span>props<\/span>.<\/span>value<\/span>)<\/span>;<\/span>\n        }<\/span>\n\n        render<\/span>(<\/span>)<\/span> {<\/span>\n            return<\/span> this<\/span>.<\/span>props<\/span>.<\/span>children<\/span>;<\/span>\n        }<\/span>\n    }<\/span>\n\n    \/\/ Consumer<\/span>\n    class<\/span> Consumer<\/span> extends<\/span> React<\/span>.<\/span>PureComponent<\/span> {<\/span>\n        constructor<\/span>(<\/span>props<\/span>)<\/span> {<\/span>\n            super<\/span>(<\/span>props<\/span>)<\/span>;<\/span>\n            this<\/span>.<\/span>state<\/span> =<\/span> {<\/span>\n                value<\/span>: defaultValue<\/span>\n            }<\/span>;<\/span>\n\n            store<\/span>.<\/span>subscribe<\/span>(<\/span>value<\/span> =><\/span> {<\/span>\n                this<\/span>.<\/span>setState<\/span>(<\/span>{<\/span>\n                        value\n                }<\/span>)<\/span>;<\/span>\n            }<\/span>)<\/span>;<\/span>\n        }<\/span>\n\n        render<\/span>(<\/span>)<\/span> {<\/span>\n            return<\/span> this<\/span>.<\/span>props<\/span>.<\/span>children<\/span>(<\/span>this<\/span>.<\/span>state<\/span>.<\/span>value<\/span>)<\/span>;<\/span>\n        }<\/span>\n    }<\/span>\n\n    return<\/span> {<\/span>\n            Provider,<\/span>\n            Consumer\n    }<\/span>;<\/span>\n}<\/span><\/pre>\n<\/div>\n
\u7528\u6211\u4eec\u5199\u7684 createContext \u66ff\u6362 React.createContext \u65b9\u6cd5\uff0c\u4f60\u4f1a\u53d1\u73b0\uff0c\u540c\u6837\u53ef\u4ee5\u8fd0\u884c\u3002<\/p>\n
\u5b83\u5176\u5b9e\u8ddf\u89e3\u51b3\u8001 Context API \u95ee\u9898\u7684\u65b9\u6cd5\u662f\u4e00\u6837\u7684\uff0c\u53ea\u4e0d\u8fc7\u662f\u505a\u4e86\u4e00\u5c42\u5c01\u88c5\u3002Consumer \u7ec4\u4ef6\u6784\u5efa\u7684\u65f6\u5019\u8fdb\u884c\u8ba2\u9605\uff0c\u5f53 Provider \u6709\u66f4\u65b0\u7684\u65f6\u5019\u8fdb\u884c\u53d1\u5e03\uff0c\u8fd9\u6837\u5c31\u8df3\u8fc7\u4e86 PureComponent  \u7684\u9650\u5236\uff0c\u5b9e\u73b0 Consumer \u7ec4\u4ef6\u7684\u66f4\u65b0\u3002<\/p>\n
createContext \u6e90\u7801<\/h3>\n
\u73b0\u5728\u6211\u4eec\u53bb\u770b\u770b\u771f\u7684 createContext \u6e90\u7801\uff0c\u6e90\u7801\u4f4d\u7f6e<\/a>\u5728 packages\/react\/src\/ReactContext.js<\/code>\uff0c\u7b80\u5316\u540e\u7684\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n