{"id":624,"date":"2025-07-14T01:38:32","date_gmt":"2025-07-14T01:38:32","guid":{"rendered":"https:\/\/boochlin.com\/?p=624"},"modified":"2026-09-19T17:04:09","modified_gmt":"2026-09-19T17:04:09","slug":"fun-gamescreengameviewmodel-gameviewmodel-gameviewmodel-%e9%80%99%e6%a8%a3%e5%af%ab%e6%9c%89%e5%95%a5%e5%95%8f%e9%a1%8c%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/boochlin.com\/?p=624","title":{"rendered":"fun GameScreen(gameViewModel: GameViewModel = GameViewModel()) \u9019\u6a23\u5beb\u6709\u5565\u554f\u984c\uff1f"},"content":{"rendered":"

\u76f4\u63a5 new GameViewModel()<\/h3>\n
class<\/span> GameViewModel<\/span> : ViewModel<\/span>() {\n    var<\/span> score by<\/span> mutableStateOf(0<\/span>)\n    init<\/span> { println("ViewModel init!"<\/span>) } \/\/ \u6bcf\u6b21\u91cd\u7d44\u90fd\u6703\u57f7\u884c<\/span>\n    override<\/span> fun<\/span> onCleared<\/span>()<\/span><\/span> { println("ViewModel cleared!"<\/span>) } \/\/ \u6c38\u9060\u4e0d\u6703\u88ab\u7cfb\u7d71\u547c\u53eb<\/span>\n}\n\n@Composable<\/span>\nfun<\/span> GameScreenWrong<\/span>(gameViewModel: GameViewModel<\/span> = GameViewModel()<\/span><\/span>) {\n    \n    \/\/ ... UI \u986f\u793a gameViewModel.score ...<\/span>\n    Button(onClick = { gameViewModel.incrementScore() }) { \/* ... *\/<\/span> }\n}<\/code><\/pre>\n
\n
\u4f7f\u7528 viewModel() \u51fd\u6578<\/h3>\n
@Composable<\/span>\nfun<\/span> GameScreenCorrect<\/span>(\n    gameViewModel: GameViewModel<\/span> = viewModel()<\/span><\/span> \/\/ <-- \u6b63\u78ba\u65b9\u5f0f\uff01<\/span>\n) {\n    \/\/ ... UI \u986f\u793a gameViewModel.score ...<\/span>\n    Button(onClick = { gameViewModel.incrementScore() }) { \/* ... *\/<\/span> }\n}<\/code><\/pre>\n
viewModel() \u662f\u4e00\u500b Composable \u51fd\u6578\uff0c\u5b83\u6703\uff1a<\/p>\n
    \n
  1. \n
    \u5c0b\u627e ViewModelStoreOwner\uff1a<\/strong> \u5411\u4e0a\u67e5\u627e\u6700\u8fd1\u7684 Activity\u3001Fragment \u6216 NavBackStackEntry\u3002<\/p>\n<\/li>\n
  2. \n
    \u5229\u7528 ViewModelProvider\uff1a<\/strong> \u900f\u904e ViewModelProvider \u53d6\u5f97\u6216\u5275\u5efa<\/strong> ViewModel \u5be6\u4f8b\u3002\u5982\u679c\u5df2\u5b58\u5728\uff0c\u5247\u8fd4\u56de\u73fe\u6709\u5be6\u4f8b\uff1b\u5982\u679c\u6c92\u6709\uff0c\u5247\u5275\u5efa\u4e26\u5b58\u5132\uff0c\u78ba\u4fdd\u8207\u5176 ViewModelStoreOwner \u751f\u547d\u9031\u671f\u7d81\u5b9a\u3002<\/p>\n<\/li>\n
  3. \n
    \u7d81\u5b9a\u751f\u547d\u9031\u671f\uff1a<\/strong> \u9019\u6a23\u7372\u53d6\u7684 ViewModel \u6703\u5728 ViewModelStoreOwner \u92b7\u6bc0\u6642\u7531\u6846\u67b6\u81ea\u52d5\u6e05\u7406\uff0c\u4e26\u547c\u53eb onCleared()\u3002<\/p>\n<\/li>\n<\/ol>\n
    \n
    \u6df1\u5ea6\u62c6\u89e3\uff1a\u76f4\u63a5 new GameViewModel() \u5230\u5e95\u5728\u5e95\u5c64\u72af\u4e86\u4ec0\u9ebc\u5fcc\u8af1\uff1f<\/h2>\n
    1. \u91cd\u7d44\u547c\u53eb\u68e7\u5c0d\u9810\u8a2d\u53c3\u6578\u7684\u91cd\u8907\u6c42\u503c\uff08Default Argument Re-evaluation\uff09<\/h3>\n
    Kotlin \u7684\u9810\u8a2d\u53c3\u6578\u4e0d\u662f\u7de8\u8b6f\u671f\u5e38\u6578\uff0c\u800c\u662f\u4e00\u500b\u7531\u7de8\u8b6f\u5668\u751f\u6210\u7684\u52d5\u614b\u6c42\u503c\u8868\u9054\u5f0f\uff08Dynamic Expression\uff09<\/strong>\u3002
    \u5728 Compose \u7de8\u8b6f\u671f\u8f49\u63db\u5f8c\uff0c\u53ea\u8981\u5916\u5c64\u89f8\u767c Recomposition\uff08\u91cd\u7d44\uff09\uff0c\u4e14\u547c\u53eb\u7aef\u672a\u986f\u5f0f\u50b3\u5165\u5be6\u4f8b\uff0c\u904b\u884c\u671f\u547c\u53eb\u68e7\u6bcf\u6b21\u90fd\u6703\u91cd\u65b0\u57f7\u884c\u4e00\u6b21 new GameViewModel()<\/code><\/strong>\uff01\u4e00\u79d2\u9418\u82e5\u91cd\u7d44\u591a\u6b21\uff0c\u5c31\u6703\u983b\u7e41\u5728 JVM \u5806\u4e0a\u5efa\u7acb\u5927\u91cf\u77ed\u547d\u7269\u4ef6\u3002<\/p>\n
    2. \u751f\u547d\u9031\u671f\u812b\u8ecc\uff1a\u7f3a\u5c11 ViewModelStoreOwner<\/code> \u7684\u5b57\u5178\u6620\u5c04<\/h3>\n
    \u6b63\u7d71\u7684 viewModel()<\/code> \u662f\u900f\u904e LocalViewModelStoreOwner.current<\/code>\uff0c\u5728 ViewModelStore<\/code> \u7684 HashMap \u5167\u90e8\u4ee5 CanonicalName \u70ba Key \u5c0b\u627e\u5feb\u53d6\uff1b\u5b58\u5728\u5247\u76f4\u63a5\u8fd4\u56de\uff0c\u4e0d\u5b58\u5728\u624d\u547c\u53eb Factory \u5be6\u4f8b\u5316\u4e26\u7d81\u5b9a Lifecycle\u3002
    \u76f4\u63a5 new GameViewModel()<\/code> \u50c5\u50c5\u662f\u5728 JVM \u5806\u4e0a\u7522\u751f\u4e00\u500b\u5b64\u5152 Java \u7269\u4ef6<\/strong>\uff1a<\/p>\n
      \n
    • \u87a2\u5e55\u65cb\u8f49\u72c0\u614b\u6b78\u96f6<\/strong>\uff1a\u6c92\u6709\u639b\u8f09\u5230 Activity \/ Fragment \u7684 ViewModelStore<\/code>\uff0cConfiguration Change \u767c\u751f\u6642\u7269\u4ef6\u76f4\u63a5\u96a8\u756b\u9762\u92b7\u6bc0\uff0c\u72c0\u614b\u5168\u90e8\u84b8\u767c\u3002<\/li>\n
    • onCleared()<\/code> \u6c38\u4e0d\u89f8\u767c<\/strong>\uff1aAndroid \u7cfb\u7d71\u58d3\u6839\u4e0d\u77e5\u9053\u5b83\u7684\u5b58\u5728\uff0cViewModel \u5167\u90e8\u555f\u52d5\u7684\u5354\u7a0b\u3001\u76e3\u807d\u5668\u5c07\u7522\u751f\u975c\u9ed8\u8a18\u61b6\u9ad4\u6d29\u6f0f\u3002<\/li>\n<\/ul>\n
      \n
      \u73fe\u4ee3\u6b63\u7d71\u67b6\u69cb\uff1a\u72c0\u614b\u63d0\u5347\uff08State Hoisting\uff09\u8207 Stateful\/Stateless \u8def\u7531\u5206\u96e2<\/h2>\n
      \u5728\u751f\u7522\u7d1a Android Compose \u67b6\u69cb\u4e2d\uff0c\u6700\u512a\u96c5\u7684\u505a\u6cd5\u4e26\u975e\u5728 Composable \u53c3\u6578\u76f4\u63a5\u4f9d\u8cf4 ViewModel\uff0c\u800c\u662f\u5c07 ViewModel \u9396\u5b9a\u5728\u8def\u7531\u5c64\uff0c\u5448\u73fe\u5c64\u7dad\u6301\u7d14\u7cb9\u7121\u72c0\u614b\uff08Stateless\uff09<\/strong>\uff1a<\/p>\n
      \/\/ 1. \u8def\u7531\u5c64\uff08Stateful\uff09\uff1a\u5c0d\u63a5 ViewModelStore \u8207 Navigation \u751f\u547d\u9031\u671f<\/span>\n@Composable<\/span>\nfun<\/span> GameRoute<\/span>(viewModel: GameViewModel<\/span> = viewModel()<\/span><\/span>) {\n    val<\/span> uiState by<\/span> viewModel.uiState.collectAsStateWithLifecycle()\n    GameScreen(\n        uiState = uiState,\n        onAction = viewModel::dispatch\n    )\n}\n\n\/\/ 2. \u5448\u73fe\u5c64\uff08Stateless\uff09\uff1a\u7d14\u7cb9\u7531 State \u9a45\u52d5\u6e32\u67d3\uff0c\u9810\u89bd\u8207\u55ae\u5143\u6e2c\u8a66 0 ViewModel \u4f9d\u8cf4<\/span>\n@Composable<\/span>\nfun<\/span> GameScreen<\/span>(\n    uiState: GameUiState<\/span>,\n    onAction: (GameAction<\/span>) -> Unit<\/span>\n)<\/span><\/span> {\n    Text(text = "Score: ${uiState.score}<\/span>"<\/span>)\n    Button(onClick = { onAction(GameAction.Increment) }) { Text("+1"<\/span>) }\n}<\/code><\/pre>\n
      \u5982\u6b64\u4e00\u4f86\uff0cUI \u9810\u89bd\u53ea\u9700\u50b3\u5165 Mock State\uff0c\u5fb9\u5e95\u544a\u5225\u9810\u8a2d\u53c3\u6578\u6ce8\u5165\u7684\u751f\u547d\u9031\u671f\u6697\u7901\uff01<\/p>\n
      \u2014<\/p>\n","protected":false},"excerpt":{"rendered":"
      \u76f4\u63a5 new GameViewModel() class GameViewModel : ViewModel( […]<\/p>\n","protected":false},"author":1,"featured_media":1250,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[86],"tags":[176,201,212,307],"_links":{"self":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts\/624"}],"collection":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=624"}],"version-history":[{"count":21,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts\/624\/revisions"}],"predecessor-version":[{"id":1556,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts\/624\/revisions\/1556"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/media\/1250"}],"wp:attachment":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=624"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=624"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=624"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}