{"id":121616,"date":"2026-11-03T05:08:38","date_gmt":"2026-11-02T21:08:38","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/121616.html"},"modified":"2026-11-03T05:08:38","modified_gmt":"2026-11-02T21:08:38","slug":"%e6%8b%86%e8%a7%a3-componentactivity-viewmodels","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/121616.html","title":{"rendered":"\u62c6\u89e3 ComponentActivity.viewModels()"},"content":{"rendered":"

\u4e00\u3001\u5148\u7ed9\u7ed3\u8bba<\/h3>\n

\u8fd9\u5341\u884c\u4ee3\u7801\u770b\u8d77\u6765\u5e73\u5e73\u65e0\u5947，\u5b9e\u9645\u4e0a\u628a Kotlin \u91cc\u4e09\u4e2a\u6700\u5bb9\u6613\u6df7\u6dc6\u7684\u8bed\u6cd5\u70b9\u4e00\u6b21\u6027\u7528\u5168\u4e86：<\/p>\n\n\u8bed\u6cd5\u70b9\u8868\u9762\u4f5c\u7528\u771f\u6b63\u89e3\u51b3\u7684\u95ee\u9898<\/tr>\n\n\n\n\n\n\n
inline<\/td>\n\u6d88\u9664 lambda \u5bf9\u8c61\u7684\u5206\u914d\u5f00\u9500<\/td>\n\u8ba9 reified \u6210\u4e3a\u53ef\u80fd<\/td>\n<\/tr>\n
reified<\/td>\n\u62ff\u5230"\u771f\u5b9e"\u7684\u6cdb\u578b\u7c7b\u578b<\/td>\nJVM \u7c7b\u578b\u64e6\u9664\u4e0b\u53d6\u5230 VM::class<\/td>\n<\/tr>\n
noinline<\/td>\n\u53c2\u6570\u4e0d\u53c2\u4e0e\u5185\u8054<\/td>\n\u8ba9 lambda \u80fd\u5b58\u8fdb\u53d8\u91cf\u3001\u5ef6\u540e\u8c03\u7528<\/td>\n<\/tr>\n
\u4e24\u5c42 lambda<\/td>\n\u628a\u8868\u8fbe\u5f0f\u5305\u6210 () -> T<\/td>\n\u62d6\u5230"\u771f\u6b63\u9700\u8981"\u65f6\u624d\u6c42\u503c<\/td>\n<\/tr>\n
\u8fd4\u56de Lazy<VM><\/td>\n\u5ef6\u8fdf\u521d\u59cb\u5316<\/td>\n\u53ea\u521b\u5efa\u4e00\u6b21 + \u5929\u7136\u652f\u6301 by \u59d4\u6258<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u4e00\u53e5\u8bdd\u6982\u62ec：\u5b83\u5728"\u8c03\u7528\u65f6"\u4ec0\u4e48\u90fd\u4e0d\u505a，\u53ea\u9020\u4e00\u4e2a Lazy \u58f3\u5b50；\u7b49\u7b2c\u4e00\u6b21\u8bbf\u95ee vm \u65f6，\u624d\u53bb\u62ff store\u3001\u9020 factory\u3001\u521b\u5efa ViewModel\u3002<\/p>\n

\u4e8c\u3001\u9010\u884c\u62c6\u89e3<\/h3>\n

public<\/span> inline<\/span> fun<\/span> <<\/span>reified<\/span> VM :<\/span> ViewModel><\/span> ComponentActivity.<\/span>viewModels<\/span>(<\/span>
\n noinline<\/span> factoryProducer:<\/span> (<\/span>(<\/span>)<\/span> -><\/span> Factory)<\/span>?<\/span> =<\/span> null<\/span>
\n)<\/span>:<\/span> Lazy<<\/span>VM><\/span> {<\/span>
\n \/\/ \u6ca1\u4f20\u5de5\u5382\u5c31\u7528\u9ed8\u8ba4\u5de5\u5382；\u6ce8\u610f\u8fd9\u91cc\u8fd4\u56de\u7684\u662f\u4e00\u4e2a lambda，\u4e0d\u662f Factory \u5b9e\u4f8b<\/span>
\n val<\/span> factoryPromise =<\/span> factoryProducer ?:<\/span> {<\/span>
\n defaultViewModelProviderFactory
\n }<\/span><\/p>\n

\/\/ \u53ea\u6784\u9020\u58f3\u5b50：\u7c7b\u578b\u3001store \u7684\u83b7\u53d6\u65b9\u5f0f\u3001\u5de5\u5382\u7684\u83b7\u53d6\u65b9\u5f0f<\/span>
\n return<\/span> ViewModelLazy<\/span>(<\/span>VM::<\/span>class<\/span>,<\/span> {<\/span> viewModelStore }<\/span>,<\/span> factoryPromise)<\/span>
\n}<\/span><\/p>\n

\u7b7e\u540d\u672c\u8eab\u4fe1\u606f\u91cf\u5c31\u5f88\u5927：<\/p>\n

    \n
  • ComponentActivity. \u2014 \u6269\u5c55\u51fd\u6570，\u53ea\u6709 Activity \u53ca\u5176\u5b50\u7c7b（AppCompatActivity \u7b49）\u80fd\u8c03\u7528<\/li>\n
  • <reified VM : ViewModel> \u2014 \u4e0a\u754c\u7ea6\u675f，\u4fdd\u8bc1\u7c7b\u578b\u5b89\u5168<\/li>\n
  • noinline factoryProducer \u2014 \u53ef\u9009\u7684\u81ea\u5b9a\u4e49\u5de5\u5382，\u9ed8\u8ba4 null<\/li>\n
  • : Lazy<VM> \u2014 \u8fd4\u56de\u7684\u4e0d\u662f ViewModel，\u800c\u662f\u4e00\u4e2a"\u7b49\u5230\u7528\u65f6\u624d\u521b\u5efa ViewModel"\u7684\u5bb9\u5668<\/li>\n<\/ul>\n

    \u4e09\u3001reified：\u4e3a\u4ec0\u4e48\u5fc5\u987b\u914d inline<\/h3>\n

    3.1 \u6ca1\u6709 reified \u4f1a\u600e\u6837<\/h4>\n

    JVM \u6cdb\u578b\u662f\u7c7b\u578b\u64e6\u9664\u7684\u3002\u666e\u901a\u6cdb\u578b\u51fd\u6570\u7f16\u8bd1\u540e，VM \u8fd9\u4e2a\u7c7b\u578b\u53c2\u6570\u5c31\u6d88\u5931\u4e86：<\/p>\n

    \/\/ \u7f16\u8bd1\u540e\u7b7e\u540d\u8fd1\u4f3c\u4e3a Object get()<\/span>
    \nfun<\/span> <<\/span>VM :<\/span> ViewModel><\/span> get<\/span>(<\/span>)<\/span>:<\/span> VM {<\/span> ..<\/span>.<\/span> }<\/span><\/p>\n

    \u51fd\u6570\u4f53\u5185\u6839\u672c\u4e0d\u77e5\u9053 VM \u5230\u5e95\u662f MyViewModel \u8fd8\u662f OtherViewModel，\u6240\u4ee5\u4e0b\u9762\u8fd9\u884c\u4ee3\u7801\u8fde\u7f16\u8bd1\u90fd\u8fc7\u4e0d\u4e86：<\/p>\n

    fun<\/span> <<\/span>VM :<\/span> ViewModel><\/span> get<\/span>(<\/span>)<\/span> =<\/span> VM::<\/span>class<\/span> \/\/ \u7f16\u8bd1\u9519\u8bef：Cannot use 'VM' as reified type parameter<\/span><\/p>\n

    \u800c ViewModelProvider \u5fc5\u987b\u62ff\u7740 KClass \u624d\u80fd\u6309\u7c7b\u540d\u53bb store \u91cc\u67e5\u3001\u53bb factory \u91cc\u5efa\u3002\u62ff\u4e0d\u5230\u7c7b\u578b，\u6574\u6761\u94fe\u8def\u5c31\u65ad\u4e86\u3002<\/p>\n

    3.2 reified \u505a\u4e86\u4ec0\u4e48<\/h4>\n

    inline + reified \u7684\u7ec4\u5408，\u672c\u8d28\u662f\u7f16\u8bd1\u5668\u5728\u8c03\u7528\u70b9\u505a\u6587\u672c\u66ff\u6362：<\/p>\n

    \/\/ \u6e90\u7801<\/span>
    \nprivate<\/span> val<\/span> vm:<\/span> MyViewModel by<\/span> viewModels<\/span>(<\/span>)<\/span><\/p>\n

    \/\/ \u7f16\u8bd1\u5668\u5728\u8c03\u7528\u70b9\u5c55\u5f00\u540e\u5927\u81f4\u7b49\u4ef7\u4e8e<\/span>
    \nViewModelLazy<\/span>(<\/span>MyViewModel::<\/span>class<\/span>,<\/span> {<\/span> viewModelStore }<\/span>,<\/span> {<\/span> defaultViewModelProviderFactory }<\/span>)<\/span><\/p>\n

    VM::class \u88ab\u539f\u5730\u66ff\u6362\u6210 MyViewModel::class \u2014\u2014 \u4e00\u4e2a\u7f16\u8bd1\u671f\u5c31\u786e\u5b9a\u7684\u5e38\u91cf\u3002\u7c7b\u578b\u53c2\u6570\u4e0d\u518d\u9700\u8981"\u8fd0\u884c\u65f6\u5b58\u5728"，\u81ea\u7136\u4e5f\u5c31\u7ed5\u5f00\u4e86\u64e6\u9664\u3002<\/p>\n

    \u6240\u4ee5 reified \u53ea\u662f\u8868\u8c61，inline \u624d\u662f\u5b9e\u73b0\u624b\u6bb5：\u51fd\u6570\u4f53\u5fc5\u987b\u80fd\u642c\u5230\u8c03\u7528\u70b9，\u624d\u53ef\u80fd\u5e26\u7740\u5177\u4f53\u7c7b\u578b\u4e00\u8d77\u642c\u3002<\/p>\n

    \u56db\u3001noinline：\u4e00\u4e2a"\u5fc5\u987b\u80fd\u88ab\u5b58\u8d77\u6765"\u7684 lambda<\/h3>\n

    inline \u51fd\u6570\u7684 lambda \u53c2\u6570\u9ed8\u8ba4\u4e5f\u4f1a\u88ab\u5185\u8054\u2014\u2014\u4e0d\u751f\u6210 Function0 \u5bf9\u8c61，\u76f4\u63a5\u5c55\u5f00\u6210\u4ee3\u7801\u5757\u3002\u4ee3\u4ef7\u662f\u5b83\u4e0d\u518d\u662f\u4e00\u4e2a\u503c：\u4e0d\u80fd\u8d4b\u7ed9\u53d8\u91cf，\u4e0d\u80fd\u8fd4\u56de，\u4e0d\u80fd\u4f20\u7ed9\u975e\u5185\u8054\u51fd\u6570\u3002<\/p>\n

    \u800c\u8fd9\u884c\u4ee3\u7801\u6070\u6070\u9700\u8981\u5b83\u662f\u4e2a\u503c：<\/p>\n

    val<\/span> factoryPromise =<\/span> factoryProducer ?:<\/span> {<\/span> defaultViewModelProviderFactory }<\/span><\/p>\n

    factoryPromise \u8981\u88ab\u8d4b\u7ed9\u5c40\u90e8\u53d8\u91cf，\u518d\u4f5c\u4e3a\u6784\u9020\u53c2\u6570\u4f20\u7ed9 ViewModelLazy，\u6700\u540e\u5728 ViewModelLazy.value \u91cc\u88ab\u5ef6\u8fdf\u8c03\u7528\u3002\u8fd9\u4e9b\u64cd\u4f5c\u90fd\u8981\u6c42\u5b83\u662f\u4e00\u4e2a\u5b9e\u5b9e\u5728\u5728\u7684 () -> Factory \u5bf9\u8c61\u3002<\/p>\n

    \u52a0\u4e0a noinline，Kotlin \u5c31\u4f1a\u4e3a\u5b83\u751f\u6210\u771f\u6b63\u7684\u51fd\u6570\u5bf9\u8c61（Function0 \u5b9e\u4f8b），\u800c\u4e0d\u662f\u628a\u5b83\u5185\u8054\u5c55\u5f00\u3002<\/p>\n

    \u4e00\u53e5\u8bdd\u8bb0\u4f4f\u533a\u522b：<\/p>\n

      \n
    • \u9ed8\u8ba4\u5185\u8054\u7684 lambda：\u5feb，\u4f46"\u7528\u5b8c\u5373\u711a"<\/li>\n
    • noinline \u7684 lambda：\u53ef\u4ee5\u5f53\u503c\u4f20\u6765\u4f20\u53bb，\u4ee3\u4ef7\u662f\u591a\u4e00\u6b21\u5bf9\u8c61\u5206\u914d<\/li>\n<\/ul>\n

      \u4e94\u3001\u4e3a\u4ec0\u4e48\u8981\u518d\u5305\u4e00\u5c42 { defaultViewModelProviderFactory }<\/h3>\n

      factoryPromise \u7684\u7c7b\u578b\u662f () -> Factory，\u6240\u4ee5\u8fd9\u91cc\u5fc5\u987b\u4f20 lambda \u800c\u4e0d\u662f defaultViewModelProviderFactory \u672c\u8eab\u3002\u4f46"\u7c7b\u578b\u5bf9\u4e0d\u4e0a"\u53ea\u662f\u8868\u5c42\u539f\u56e0，\u771f\u6b63\u6709\u4ef7\u503c\u7684\u662f\u5ef6\u8fdf\u6c42\u503c：<\/p>\n

      \u7b2c\u4e00，\u5de5\u5382\u53ea\u5728\u771f\u7684\u9700\u8981\u521b\u5efa ViewModel \u65f6\u624d\u6784\u9020\u3002
      \ndefaultViewModelProviderFactory \u5185\u90e8\u4f1a\u521b\u5efa SavedStateViewModelFactory，\u9700\u8981 Application\u3001SavedStateRegistryOwner\u3001Fragment \u7684 arguments \u7b49\u4e00\u5806\u4e1c\u897f\u3002\u5982\u679c viewModels() \u4e00\u8c03\u7528\u5c31\u628a\u5de5\u5382\u9020\u51fa\u6765，\u90a3\u4e48"\u58f0\u660e\u4e86\u4f46\u8fd9\u6b21\u6ca1\u7528\u4e0a"\u7684\u60c5\u51b5\u5c31\u767d\u4ed8\u4e86\u8fd9\u4efd\u5f00\u9500\u3002<\/p>\n

      \u7b2c\u4e8c，\u4fdd\u8bc1\u62ff\u5230\u7684\u662f"\u5f53\u524d\u5bf9\u8c61"\u7684\u5b9e\u73b0\u3002
      \n\u5c5e\u6027\u662f\u5728 lambda \u91cc\u8bfb\u7684，\u8bfb\u7684\u65f6\u673a\u662f Lazy \u9996\u6b21 get()\u3002FragmentActivity \u8986\u5199\u4e86 defaultViewModelProviderFactory \u8fd4\u56de\u5e26\u53c2\u6570\u652f\u6301\u7684\u5de5\u5382\u2014\u2014\u5ef6\u8fdf\u8bfb\u53d6\u8ba9\u591a\u6001\u5728\u4efb\u4f55\u65f6\u5019\u90fd\u6210\u7acb\u3002<\/p>\n

      \u540c\u6837\u7684\u9053\u7406，{ viewModelStore } \u8fd9\u5c42 lambda \u66f4\u662f\u5173\u952e\u7684\u4fdd\u547d\u8bbe\u8ba1：<\/p>\n

      private<\/span> val<\/span> vm:<\/span> MyViewModel by<\/span> viewModels<\/span>(<\/span>)<\/span> \/\/ \u5199\u5728\u5b57\u6bb5\u521d\u59cb\u5316\u5904<\/span><\/p>\n

      by viewModels() \u5728\u5b57\u6bb5\u521d\u59cb\u5316\u9636\u6bb5\u6267\u884c，\u6b64\u65f6 Activity \u8fd8\u6ca1 attach \u5230 Application\u3002\u800c getViewModelStore() \u5728\u672a attach \u65f6\u4f1a\u76f4\u63a5\u629b\u5f02\u5e38：<\/p>\n

      IllegalStateException: Your activity is not yet attached to the Application instance.
      \nYou can't request ViewModel before onCreate call.<\/p>\n

      \u56e0\u4e3a lambda \u88ab\u5ef6\u8fdf\u5230\u9996\u6b21\u8bbf\u95ee vm \u65f6\u624d\u6267\u884c，\u800c\u90a3\u65f6 Activity \u65e9\u5df2\u8fdb\u5165 onCreate，\u6240\u4ee5\u8fd9\u6bb5\u4ee3\u7801\u5b89\u5168\u3002\u628a viewModelStore \u76f4\u63a5\u5f53\u53c2\u6570\u4f20，\u8fd9\u884c\u4ee3\u7801\u5728\u5b57\u6bb5\u521d\u59cb\u5316\u5904\u5c31\u4f1a\u5d29\u3002<\/p>\n

      \u516d\u3001ViewModelLazy：\u771f\u6b63\u7684\u521b\u5efa\u53d1\u751f\u5728\u7b2c\u4e00\u6b21 get()<\/h3>\n

      ViewModelLazy \u662f\u4e00\u4e2a Lazy<VM> \u7684\u5b9e\u73b0，\u7b80\u5316\u540e\u5927\u81f4\u957f\u8fd9\u6837：<\/p>\n

      public<\/span> class<\/span> ViewModelLazy<<\/span>VM :<\/span> ViewModel><\/span>(<\/span>
      \n private<\/span> val<\/span> viewModelClass:<\/span> KClass<<\/span>VM><\/span>,<\/span>
      \n private<\/span> val<\/span> storeProducer:<\/span> (<\/span>)<\/span> -><\/span> ViewModelStore,<\/span>
      \n private<\/span> val<\/span> factoryProducer:<\/span> (<\/span>)<\/span> -><\/span> ViewModelProvider.<\/span>Factory
      \n)<\/span> :<\/span> Lazy<<\/span>VM><\/span> {<\/span><\/p>\n

      private<\/span> var<\/span> cached:<\/span> VM?<\/span> =<\/span> null<\/span><\/p>\n

      override<\/span> val<\/span> value:<\/span> VM
      \n get<\/span>(<\/span>)<\/span> {<\/span>
      \n val<\/span> viewModel =<\/span> cached
      \n if<\/span> (<\/span>viewModel !=<\/span> null<\/span>)<\/span> return<\/span> viewModel \/\/ \u547d\u4e2d\u7f13\u5b58，\u76f4\u63a5\u8fd4\u56de<\/span><\/p>\n

      \/\/ \u9996\u6b21\u8bbf\u95ee：\u6b64\u65f6\u624d\u53bb\u78b0 store \u548c factory<\/span>
      \n val<\/span> factory =<\/span> factoryProducer<\/span>(<\/span>)<\/span>
      \n val<\/span> store =<\/span> storeProducer<\/span>(<\/span>)<\/span>
      \n return<\/span> ViewModelProvider<\/span>(<\/span>store,<\/span> factory)<\/span>
      \n .<\/span>get<\/span>(<\/span>viewModelClass)<\/span>
      \n .<\/span>also<\/span> {<\/span> cached =<\/span> it }<\/span>
      \n }<\/span><\/p>\n

      override<\/span> fun<\/span> isInitialized<\/span>(<\/span>)<\/span>:<\/span> Boolean =<\/span> cached !=<\/span> null<\/span>
      \n}<\/span><\/p>\n

      \u6ce8\u610f\u4e24\u4e2a\u7ec6\u8282：<\/p>\n

    • \u5b83\u662f\u81ea\u5df1\u5b9e\u73b0\u7684\u7f13\u5b58，\u4e0d\u4f9d\u8d56 lazy {}\u3002 \u6ca1\u6709 synchronized，\u4e5f\u6ca1\u6709 LazyThreadSafetyMode\u2014\u2014\u56e0\u4e3a\u5b83\u7ea6\u5b9a\u53ea\u5728\u4e3b\u7ebf\u7a0b\u8bbf\u95ee，\u52a0\u9501\u7eaf\u5c5e\u6d6a\u8d39\u3002<\/li>\n
    • cached \u4e00\u65e6\u8d4b\u503c\u5c31\u6c38\u4e45\u6301\u6709\u3002 \u6240\u4ee5\u540c\u4e00\u4e2a Activity \u91cc\u53cd\u590d\u8bbf\u95ee vm，\u62ff\u5230\u7684\u59cb\u7ec8\u662f\u540c\u4e00\u4e2a\u5b9e\u4f8b\u3002<\/li>\n

      \u5f80\u4e0b\u518d\u8d70\u4e00\u5c42，ViewModelProvider.get(KClass) \u6700\u7ec8\u843d\u5230 get(key)：<\/p>\n

      \/\/ \u7b80\u5316\u7684\u6838\u5fc3\u903b\u8f91<\/span>
      \nval<\/span> viewModel =<\/span> store[<\/span>key]<\/span> \/\/ \u5148\u4ece store \u91cc\u627e<\/span>
      \nreturn<\/span> viewModel ?:<\/span> factory.<\/span>create<\/span>(<\/span>modelClass)<\/span> \/\/ \u627e\u4e0d\u5230\u624d\u521b\u5efa<\/span>
      \n .<\/span>also<\/span> {<\/span> store.<\/span>put<\/span>(<\/span>key,<\/span> it)<\/span> }<\/span> \/\/ \u521b\u5efa\u540e\u5b58\u56de store<\/span><\/p>\n

      \u5176\u4e2d key \u9ed8\u8ba4\u5c31\u662f VM::class.java.canonicalName\u3002\u8fd9\u89e3\u91ca\u4e86\u4e3a\u4ec0\u4e48\u540c\u4e00\u4e2a Activity \u91cc\u58f0\u660e\u4e24\u4e2a\u4e0d\u540c\u7c7b\u578b\u7684 ViewModel \u4e0d\u4f1a\u4e92\u76f8\u8986\u76d6\u2014\u2014\u7c7b\u540d\u4e0d\u540c，key \u5c31\u4e0d\u540c\u3002<\/p>\n

      \u4e03\u3001\u5b8c\u6574\u94fe\u8def：by viewModels() \u5230\u5e95\u8d70\u5230\u54ea<\/h3>\n

      by \u59d4\u6258\u53ea\u8981\u6c42\u88ab\u59d4\u6258\u5bf9\u8c61\u63d0\u4f9b getValue \u64cd\u4f5c\u7b26，\u800c Lazy \u6070\u597d\u6709，\u6240\u4ee5 Lazy<VM> \u5929\u751f\u53ef\u4ee5 by：<\/p>\n

      private<\/span> val<\/span> vm:<\/span> MyViewModel by<\/span> viewModels<\/span>(<\/span>)<\/span><\/p>\n

      \/\/ \u7b49\u4ef7\u4e8e<\/span>
      \nprivate<\/span> val<\/span> vm$delegate =<\/span> viewModels<<\/span>MyViewModel><\/span>(<\/span>)<\/span>
      \nprivate<\/span> val<\/span> vm:<\/span> MyViewModel get<\/span>(<\/span>)<\/span> =<\/span> vm$delegate.<\/span>value<\/p>\n

      \u6574\u6761\u94fe\u8def\u7684\u65f6\u5e8f：<\/p>\n\n\u65f6\u673a\u53d1\u751f\u4e86\u4ec0\u4e48<\/tr>\n\n\n\n\n\n
      Activity \u5b57\u6bb5\u521d\u59cb\u5316<\/td>\n\u53ea\u521b\u5efa ViewModelLazy \u5bf9\u8c61，store \u548c factory \u90fd\u8fd8\u662f\u5f85\u6267\u884c\u7684 lambda<\/td>\n<\/tr>\n
      onCreate \u53ca\u4e4b\u540e\u9996\u6b21\u8bbf\u95ee vm<\/td>\n\u89e6\u53d1 value getter：factoryProducer() \u2192 storeProducer() \u2192 ViewModelProvider.get()<\/td>\n<\/tr>\n
      \u4e4b\u540e\u6bcf\u6b21\u8bbf\u95ee vm<\/td>\ncached \u547d\u4e2d，\u76f4\u63a5\u8fd4\u56de，\u65e0\u4efb\u4f55\u5f00\u9500<\/td>\n<\/tr>\n
      \u914d\u7f6e\u53d8\u66f4（\u65cb\u8f6c\u5c4f\u5e55）<\/td>\nActivity \u91cd\u5efa，ViewModelStore \u88ab NonConfigurationInstances \u4fdd\u7559\u4e0b\u6765，\u65b0 Activity \u4ece\u540c\u4e00\u4e2a store \u91cc\u53d6\u56de\u65e7\u5b9e\u4f8b<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      \u516b\u3001\u51e0\u4e2a\u5bb9\u6613\u8bef\u89e3\u7684\u70b9<\/h3>\n

      1. \u4f20\u81ea\u5b9a\u4e49 Factory，\u6784\u9020\u9700\u8981\u53c2\u6570\u7684 ViewModel<\/p>\n

      private<\/span> val<\/span> vm:<\/span> DetailViewModel by<\/span> viewModels {<\/span>
      \n object<\/span> :<\/span> ViewModelProvider.<\/span>Factory<\/span> {<\/span>
      \n override<\/span> fun<\/span> <<\/span>T :<\/span> ViewModel><\/span> create<\/span>(<\/span>modelClass:<\/span> Class<<\/span>T><\/span>)<\/span>:<\/span> T {<\/span>
      \n @Suppress<\/span>(<\/span>"UNCHECKED_CAST"<\/span><\/span>)<\/span>
      \n return<\/span> DetailViewModel<\/span>(<\/span>repository)<\/span> as<\/span> T
      \n }<\/span>
      \n }<\/span>
      \n}<\/span><\/p>\n

      \u8fd9\u91cc\u7684 lambda \u5c31\u662f factoryProducer，\u56e0\u4e3a\u6807\u4e86 noinline \u624d\u5141\u8bb8\u5199\u6210\u5c3e\u968f lambda \u5f62\u5f0f\u3002<\/p>\n

      2. viewModels() \u4e0e activityViewModels() \u4e0d\u662f\u4e00\u56de\u4e8b<\/p>\n

        \n
      • by viewModels() \u2014\u2014 \u4f5c\u7528\u57df\u662f\u5f53\u524d\u7ec4\u4ef6\u81ea\u5df1\u7684 ViewModelStore<\/li>\n
      • Fragment \u91cc\u60f3\u8981 Activity \u7684\u4f5c\u7528\u57df，\u7528 by activityViewModels()（\u6765\u81ea androidx.fragment）<\/li>\n<\/ul>\n

        3. ViewModel \u4e0d\u662f"\u4ec0\u4e48\u90fd\u4e0d\u6301\u6709"<\/p>\n

        \u5b83\u4e0d\u6301\u6709 Activity\/Fragment，\u4f46\u53ef\u4ee5\u6301\u6709 Application\u3002\u8fd9\u4e5f\u89e3\u91ca\u4e86\u4e3a\u4ec0\u4e48 AndroidViewModel \u9700\u8981\u4f20 Application\u3002<\/p>\n

        4. \u522b\u5728 Lazy \u8fd8\u6ca1\u521d\u59cb\u5316\u65f6\u5c31\u53bb\u6478 store<\/p>\n

        \u4efb\u4f55\u5728 onCreate \u4e4b\u524d\u8bbf\u95ee viewModelStore \u7684\u4ee3\u7801\u90fd\u4f1a\u8e29\u5230\u4e0a\u9762\u90a3\u4e2a IllegalStateException\u3002viewModels() \u9760 lambda \u628a\u8fd9\u4e00\u6b65\u63a8\u8fdf\u4e86，\u4f46\u8fd9\u4e0d\u4ee3\u8868\u53ef\u4ee5\u81ea\u5df1\u5728\u6784\u9020\u51fd\u6570\u91cc\u76f4\u63a5\u5199 viewModelStore\u3002<\/p>\n

        \u4e5d\u3001\u5c0f\u7ed3<\/h3>\n
          \n
        • inline \u4e0d\u662f\u4e3a\u4e86\u6027\u80fd，\u800c\u662f\u4e3a\u4e86\u8ba9 reified \u53ef\u884c\u2014\u2014\u51fd\u6570\u4f53\u5fc5\u987b\u80fd\u5728\u8c03\u7528\u70b9\u5c55\u5f00，VM::class \u624d\u80fd\u88ab\u66ff\u6362\u6210\u5177\u4f53\u7c7b<\/li>\n
        • noinline \u662f\u4e3a\u4e86\u8ba9 lambda \u80fd\u5f53\u503c\u5b58\u8d77\u6765\u2014\u2014\u5b83\u8981\u88ab\u8d4b\u7ed9\u53d8\u91cf\u3001\u5ef6\u8fdf\u5230 Lazy \u5185\u90e8\u8c03\u7528，\u4e0d\u80fd"\u7528\u5b8c\u5373\u711a"<\/li>\n
        • \u4e24\u5c42 lambda \u662f\u5ef6\u8fdf\u6c42\u503c\u7684\u8f7d\u4f53\u2014\u2014\u65e2\u7701\u6389\u4e86\u4e0d\u5fc5\u8981\u7684\u5de5\u5382\u6784\u9020，\u4e5f\u907f\u514d\u5728 Activity attach \u4e4b\u524d\u8bbf\u95ee viewModelStore \u629b\u5f02\u5e38<\/li>\n
        • Lazy \u662f\u7f13\u5b58 + \u59d4\u6258\u7684\u53cc\u91cd\u6536\u76ca\u2014\u2014\u540c\u4e00\u4e2a Activity \u5185\u53ea\u521b\u5efa\u4e00\u6b21，\u540c\u65f6\u5929\u7136\u652f\u6301 by \u8bed\u6cd5<\/li>\n<\/ul>\n

          \u5341\u884c\u4ee3\u7801，\u6ca1\u6709\u4e00\u884c\u662f\u591a\u4f59\u7684\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

          \u4e00\u3001\u5148\u7ed9\u7ed3\u8bba
          \n\u8fd9\u5341\u884c\u4ee3\u7801\u770b\u8d77\u6765\u5e73\u5e73\u65e0\u5947，\u5b9e\u9645\u4e0a\u628a Kotlin \u91cc\u4e09\u4e2a\u6700\u5bb9\u6613\u6df7\u6dc6\u7684\u8bed\u6cd5\u70b9\u4e00\u6b21\u6027\u7528\u5168\u4e86：\u8bed\u6cd5\u70b9\u8868\u9762\u4f5c\u7528\u771f\u6b63\u89e3\u51b3\u7684\u95ee\u9898inline\u6d88\u9664 lambda \u5bf9\u8c61\u7684\u5206\u914d\u5f00\u9500\u8ba9 reified \u6210\u4e3a\u53ef\u80fdreified\u62ff\u5230\\”\u771f\u5b9e\\”\u7684\u6cdb\u578b\u7c7b\u578bJVM \u7c7b\u578b\u64e6\u9664\u4e0b\u53d6\u5230 VM::classnoinline\u53c2\u6570\u4e0d\u53c2\u4e0e\u5185\u8054\u8ba9 lambda \u80fd\u5b58\u8fdb\u53d8\u91cf\u3001\u5ef6\u540e\u8c03\u7528\u4e24\u5c42 lambda\u628a\u8868\u8fbe\u5f0f\u5305\u6210 () -> T\u62d6\u5230\\”\u771f\u6b63\u9700\u8981\\”\u65f6\u624d\u6c42\u503c\u8fd4\u56de Lazy\u5ef6\u8fdf\u521d\u59cb\u5316<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[84,5754,1220,2801,1693],"topic":[],"class_list":["post-121616","post","type-post","status-publish","format-standard","hentry","category-server","tag-android","tag-android-jetpack","tag-android-studio","tag-gradle","tag-kotlin"],"yoast_head":"\n\u62c6\u89e3 ComponentActivity.viewModels() - 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