{"id":515,"date":"2025-06-18T17:49:31","date_gmt":"2025-06-18T09:49:31","guid":{"rendered":"https:\/\/trantor.ink\/?p=515"},"modified":"2025-06-18T17:49:31","modified_gmt":"2025-06-18T09:49:31","slug":"android%e4%b8%ad-livedata-%e6%9c%80%e4%bd%b3%e5%ae%9e%e8%b7%b5%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/trantor.ink\/?p=515","title":{"rendered":"android\u4e2d LiveData \u6700\u4f73\u5b9e\u8df5\uff1f"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_81 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/trantor.ink\/?p=515\/#1_%E4%BD%BF%E7%94%A8_MutableLiveData_%E5%92%8C_LiveData\" >1. \u4f7f\u7528 MutableLiveData \u548c LiveData<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/trantor.ink\/?p=515\/#2_%E4%BD%BF%E7%94%A8_Observer_%E8%AE%A2%E9%98%85%E6%95%B0%E6%8D%AE%E5%8F%98%E5%8C%96\" >2. \u4f7f\u7528 Observer \u8ba2\u9605\u6570\u636e\u53d8\u5316<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/trantor.ink\/?p=515\/#3_%E9%81%BF%E5%85%8D%E5%9C%A8%E4%B8%BB%E7%BA%BF%E7%A8%8B%E4%B8%AD%E8%BF%9B%E8%A1%8C%E9%95%BF%E6%97%B6%E9%97%B4%E6%93%8D%E4%BD%9C\" >3. \u907f\u514d\u5728\u4e3b\u7ebf\u7a0b\u4e2d\u8fdb\u884c\u957f\u65f6\u95f4\u64cd\u4f5c<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/trantor.ink\/?p=515\/#4_%E4%BD%BF%E7%94%A8_Transformations\" >4. \u4f7f\u7528 Transformations<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/trantor.ink\/?p=515\/#5_%E5%90%88%E7%90%86%E4%BD%BF%E7%94%A8_MediatorLiveData\" >5. \u5408\u7406\u4f7f\u7528 MediatorLiveData<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/trantor.ink\/?p=515\/#6_%E9%81%BF%E5%85%8D%E5%86%85%E5%AD%98%E6%B3%84%E6%BC%8F\" >6. \u907f\u514d\u5185\u5b58\u6cc4\u6f0f<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/trantor.ink\/?p=515\/#7_%E4%BD%BF%E7%94%A8_distinctUntilChanged\" >7. \u4f7f\u7528 distinctUntilChanged<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/trantor.ink\/?p=515\/#8_%E4%BD%BF%E7%94%A8_SingleLiveEvent_%E5%A4%84%E7%90%86%E4%B8%80%E6%AC%A1%E6%80%A7%E4%BA%8B%E4%BB%B6\" >8. \u4f7f\u7528 SingleLiveEvent \u5904\u7406\u4e00\u6b21\u6027\u4e8b\u4ef6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/trantor.ink\/?p=515\/#9_%E6%B5%8B%E8%AF%95_LiveData\" >9. \u6d4b\u8bd5 LiveData<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/trantor.ink\/?p=515\/#10_%E9%81%BF%E5%85%8D%E5%9C%A8_ViewModel_%E4%B8%AD%E6%9A%B4%E9%9C%B2_MutableLiveData\" >10. \u907f\u514d\u5728 ViewModel \u4e2d\u66b4\u9732 MutableLiveData<\/a><\/li><\/ul><\/nav><\/div>\n\n<p class=\"wp-block-paragraph\">\u5728 Android \u4e2d\u4f7f\u7528 <code>LiveData<\/code> \u662f\u4e00\u79cd\u6709\u6548\u7684\u6570\u636e\u89c2\u5bdf\u548c\u54cd\u5e94\u673a\u5236\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u6700\u4f73\u5b9e\u8df5\uff0c\u53ef\u4ee5\u5e2e\u52a9\u4f60\u5728\u5e94\u7528\u4e2d\u66f4\u597d\u5730\u4f7f\u7528 <code>LiveData<\/code>\uff1a<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"1_%E4%BD%BF%E7%94%A8_MutableLiveData_%E5%92%8C_LiveData\"><\/span>1. \u4f7f\u7528 <code>MutableLiveData<\/code> \u548c <code>LiveData<\/code><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728 <code>ViewModel<\/code> \u4e2d\u4f7f\u7528 <code>MutableLiveData<\/code> \u8fdb\u884c\u6570\u636e\u7684\u66f4\u6539\uff0c\u800c\u5728\u5916\u90e8\u4ec5\u66b4\u9732\u4e0d\u53ef\u53d8\u7684 <code>LiveData<\/code> \u4ee5\u786e\u4fdd\u6570\u636e\u4e0d\u53ef\u88ab\u5916\u90e8\u4fee\u6539\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class MyViewModel : ViewModel() {\n    private val _data = MutableLiveData&lt;String>()\n    val data: LiveData&lt;String> get() = _data\n\n    fun updateData(newData: String) {\n        _data.value = newData\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"2_%E4%BD%BF%E7%94%A8_Observer_%E8%AE%A2%E9%98%85%E6%95%B0%E6%8D%AE%E5%8F%98%E5%8C%96\"><\/span>2. \u4f7f\u7528 <code>Observer<\/code> \u8ba2\u9605\u6570\u636e\u53d8\u5316<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728 <code>Activity<\/code> \u6216 <code>Fragment<\/code> \u4e2d\u4f7f\u7528 <code>Observer<\/code> \u6765\u8ba2\u9605 <code>LiveData<\/code> \u7684\u6570\u636e\u53d8\u5316\uff0c\u5e76\u5728\u6570\u636e\u53d8\u5316\u65f6\u66f4\u65b0 UI\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">viewModel.data.observe(viewLifecycleOwner, Observer { newData ->\n    \/\/ Update UI\n    textView.text = newData\n})<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"3_%E9%81%BF%E5%85%8D%E5%9C%A8%E4%B8%BB%E7%BA%BF%E7%A8%8B%E4%B8%AD%E8%BF%9B%E8%A1%8C%E9%95%BF%E6%97%B6%E9%97%B4%E6%93%8D%E4%BD%9C\"><\/span>3. \u907f\u514d\u5728\u4e3b\u7ebf\u7a0b\u4e2d\u8fdb\u884c\u957f\u65f6\u95f4\u64cd\u4f5c<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u957f\u65f6\u95f4\u64cd\u4f5c\u5e94\u5728\u540e\u53f0\u7ebf\u7a0b\u4e2d\u5b8c\u6210\uff0c\u5e76\u5c06\u7ed3\u679c\u901a\u8fc7 <code>LiveData<\/code> \u66f4\u65b0\u5230\u4e3b\u7ebf\u7a0b\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">fun fetchData() {\n    viewModelScope.launch {\n        val data = repository.getData()\n        _data.postValue(data)\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"4_%E4%BD%BF%E7%94%A8_Transformations\"><\/span>4. \u4f7f\u7528 Transformations<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5229\u7528 <code>Transformations<\/code> \u5bf9 <code>LiveData<\/code> \u8fdb\u884c\u8f6c\u6362\uff0c\u907f\u514d\u5728 <code>ViewModel<\/code> \u4e4b\u5916\u8fdb\u884c\u6570\u636e\u5904\u7406\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">val transformedData: LiveData&lt;String> = Transformations.map(_data) { data ->\n    data.toUpperCase(Locale.ROOT)\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"5_%E5%90%88%E7%90%86%E4%BD%BF%E7%94%A8_MediatorLiveData\"><\/span>5. \u5408\u7406\u4f7f\u7528 <code>MediatorLiveData<\/code><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5f53\u9700\u8981\u89c2\u5bdf\u591a\u4e2a <code>LiveData<\/code> \u5e76\u5408\u5e76\u5b83\u4eec\u7684\u6570\u636e\u65f6\uff0c\u4f7f\u7528 <code>MediatorLiveData<\/code>\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">val combinedData = MediatorLiveData&lt;String>().apply {\n    addSource(liveData1) { value = it }\n    addSource(liveData2) { value = it }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"6_%E9%81%BF%E5%85%8D%E5%86%85%E5%AD%98%E6%B3%84%E6%BC%8F\"><\/span>6. \u907f\u514d\u5185\u5b58\u6cc4\u6f0f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>LiveData<\/code> \u662f\u751f\u547d\u5468\u671f\u611f\u77e5\u7684\uff0c\u4f46\u5728\u4f7f\u7528 <code>Observer<\/code> \u65f6\u4ecd\u9700\u6ce8\u610f\u5185\u5b58\u6cc4\u6f0f\uff0c\u786e\u4fdd\u5728 <code>onDestroy<\/code> \u6216 <code>onDestroyView<\/code> \u4e2d\u79fb\u9664 <code>Observer<\/code>\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">override fun onDestroyView() {\n    super.onDestroyView()\n    viewModel.data.removeObservers(viewLifecycleOwner)\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"7_%E4%BD%BF%E7%94%A8_distinctUntilChanged\"><\/span>7. \u4f7f\u7528 <code>distinctUntilChanged<\/code><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728\u89c2\u5bdf <code>LiveData<\/code> \u65f6\uff0c\u4f7f\u7528 <code>distinctUntilChanged<\/code> \u53ea\u5728\u6570\u636e\u771f\u6b63\u53d8\u5316\u65f6\u66f4\u65b0 UI\uff0c\u907f\u514d\u4e0d\u5fc5\u8981\u7684 UI \u5237\u65b0\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">val distinctData: LiveData&lt;String> = Transformations.distinctUntilChanged(_data)<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"8_%E4%BD%BF%E7%94%A8_SingleLiveEvent_%E5%A4%84%E7%90%86%E4%B8%80%E6%AC%A1%E6%80%A7%E4%BA%8B%E4%BB%B6\"><\/span>8. \u4f7f\u7528 <code>SingleLiveEvent<\/code> \u5904\u7406\u4e00\u6b21\u6027\u4e8b\u4ef6<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5bf9\u4e8e\u4e00\u6b21\u6027\u4e8b\u4ef6\uff08\u5982\u5bfc\u822a\u3001\u663e\u793a Snackbar\uff09\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>SingleLiveEvent<\/code> \u6216\u7c7b\u4f3c\u673a\u5236\uff0c\u4ee5\u786e\u4fdd\u4e8b\u4ef6\u53ea\u5904\u7406\u4e00\u6b21\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class SingleLiveEvent&lt;T> : MutableLiveData&lt;T>() {\n    private val pending = AtomicBoolean(false)\n\n    override fun observe(owner: LifecycleOwner, observer: Observer&lt;in T>) {\n        super.observe(owner, Observer { t ->\n            if (pending.compareAndSet(true, false)) {\n                observer.onChanged(t)\n            }\n        })\n    }\n\n    override fun setValue(t: T?) {\n        pending.set(true)\n        super.setValue(t)\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"9_%E6%B5%8B%E8%AF%95_LiveData\"><\/span>9. \u6d4b\u8bd5 <code>LiveData<\/code><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5229\u7528 <code>InstantTaskExecutorRule<\/code> \u548c <code>LiveData<\/code> \u7684\u6d4b\u8bd5\u5de5\u5177\uff08\u5982 <code>LiveDataTestUtil<\/code>\uff09\uff0c\u7f16\u5199\u5355\u5143\u6d4b\u8bd5\u6765\u6d4b\u8bd5 <code>LiveData<\/code> \u7684\u884c\u4e3a\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@get:Rule\nval instantTaskExecutorRule = InstantTaskExecutorRule()\n\n@Test\nfun testLiveData() {\n    val liveData = MutableLiveData&lt;String>()\n    liveData.value = \"test\"\n    val value = LiveDataTestUtil.getValue(liveData)\n    assertEquals(\"test\", value)\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"10_%E9%81%BF%E5%85%8D%E5%9C%A8_ViewModel_%E4%B8%AD%E6%9A%B4%E9%9C%B2_MutableLiveData\"><\/span>10. \u907f\u514d\u5728 <code>ViewModel<\/code> \u4e2d\u66b4\u9732 <code>MutableLiveData<\/code><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u786e\u4fdd <code>ViewModel<\/code> \u4e2d\u66b4\u9732\u7684 <code>LiveData<\/code> \u662f\u53ea\u8bfb\u7684\uff0c\u9632\u6b62\u5916\u90e8\u7ec4\u4ef6\u610f\u5916\u4fee\u6539\u6570\u636e\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class MyViewModel : ViewModel() {\n    private val _data = MutableLiveData&lt;String>()\n    val data: LiveData&lt;String> get() = _data\n}<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u901a\u8fc7\u9075\u5faa\u8fd9\u4e9b\u6700\u4f73\u5b9e\u8df5\uff0c\u4f60\u53ef\u4ee5\u5728 Android \u5e94\u7528\u4e2d\u66f4\u597d\u5730\u4f7f\u7528 <code>LiveData<\/code>\uff0c\u5b9e\u73b0\u66f4\u6e05\u6670\u3001\u53ef\u9760\u548c\u9ad8\u6548\u7684\u6570\u636e\u7ba1\u7406\u548c UI \u66f4\u65b0\u673a\u5236\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728 Android \u4e2d\u4f7f\u7528 LiveData \u662f\u4e00\u79cd\u6709\u6548\u7684\u6570\u636e\u89c2\u5bdf\u548c\u54cd\u5e94\u673a\u5236\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u6700\u4f73\u5b9e\u8df5\uff0c\u53ef\u4ee5\u5e2e\u52a9\u4f60\u5728\u5e94\u7528\u4e2d\u66f4\u597d\u5730\u4f7f\u7528 LiveData\uff1a 1. \u4f7f\u7528 MutableLiveData \u548c LiveData \u5728 ViewModel \u4e2d\u4f7f\u7528 MutableLiveData \u8fdb\u884c\u6570\u636e\u7684\u66f4\u6539\uff0c\u800c\u5728\u5916\u90e8\u4ec5\u66b4\u9732\u4e0d\u53ef\u53d8\u7684 LiveData \u4ee5\u786e\u4fdd\u6570\u636e\u4e0d\u53ef\u88ab\u5916\u90e8\u4fee\u6539\u3002 2. \u4f7f\u7528 Observer \u8ba2\u9605\u6570\u636e\u53d8\u5316 \u5728 Activity \u6216 Fragment \u4e2d\u4f7f\u7528 Observer \u6765\u8ba2\u9605 LiveData \u7684\u6570\u636e\u53d8\u5316\uff0c\u5e76\u5728\u6570\u636e\u53d8\u5316\u65f6\u66f4\u65b0 UI\u3002 3. \u907f\u514d\u5728\u4e3b\u7ebf\u7a0b\u4e2d\u8fdb\u884c\u957f\u65f6\u95f4\u64cd\u4f5c \u957f\u65f6\u95f4\u64cd\u4f5c\u5e94\u5728\u540e\u53f0\u7ebf\u7a0b\u4e2d\u5b8c\u6210\uff0c\u5e76\u5c06\u7ed3\u679c\u901a\u8fc7 LiveData \u66f4\u65b0\u5230\u4e3b\u7ebf\u7a0b\u3002 4. \u4f7f\u7528 Transformations \u5229\u7528 Transformations \u5bf9 LiveData \u8fdb\u884c\u8f6c\u6362\uff0c\u907f\u514d\u5728 ViewModel \u4e4b\u5916\u8fdb\u884c\u6570\u636e\u5904\u7406\u3002 5. \u5408\u7406\u4f7f\u7528 MediatorLiveData \u5f53\u9700\u8981\u89c2\u5bdf\u591a\u4e2a LiveData \u5e76\u5408\u5e76\u5b83\u4eec\u7684\u6570\u636e\u65f6\uff0c\u4f7f\u7528 MediatorLiveData\u3002 6. \u907f\u514d\u5185\u5b58\u6cc4\u6f0f LiveData \u662f\u751f\u547d\u5468\u671f\u611f\u77e5\u7684\uff0c\u4f46\u5728\u4f7f\u7528 Observer \u65f6\u4ecd\u9700\u6ce8\u610f\u5185\u5b58\u6cc4\u6f0f\uff0c\u786e\u4fdd\u5728 onDestroy \u6216 onDestroyView \u4e2d\u79fb\u9664 Observer\u3002 7. \u4f7f\u7528 distinctUntilChanged \u5728\u89c2\u5bdf LiveData \u65f6\uff0c\u4f7f\u7528 distinctUntilChanged \u53ea\u5728\u6570\u636e\u771f\u6b63\u53d8\u5316\u65f6\u66f4\u65b0 UI\uff0c\u907f\u514d\u4e0d\u5fc5\u8981\u7684 UI \u5237\u65b0\u3002 8. \u4f7f\u7528 SingleLiveEvent \u5904\u7406\u4e00\u6b21\u6027\u4e8b\u4ef6 \u5bf9\u4e8e\u4e00\u6b21\u6027\u4e8b\u4ef6\uff08\u5982\u5bfc\u822a\u3001\u663e\u793a Snackbar\uff09\uff0c\u53ef\u4ee5\u4f7f\u7528 SingleLiveEvent \u6216\u7c7b\u4f3c\u673a\u5236\uff0c\u4ee5\u786e\u4fdd\u4e8b\u4ef6\u53ea\u5904\u7406\u4e00\u6b21\u3002 9. \u6d4b\u8bd5 LiveData \u5229\u7528 InstantTaskExecutorRule \u548c LiveData \u7684\u6d4b\u8bd5\u5de5\u5177\uff08\u5982 LiveDataTestUtil\uff09\uff0c\u7f16\u5199\u5355\u5143\u6d4b\u8bd5\u6765\u6d4b\u8bd5 LiveData \u7684\u884c\u4e3a\u3002 10. \u907f\u514d\u5728 ViewModel \u4e2d\u66b4\u9732 MutableLiveData \u786e\u4fdd ViewModel \u4e2d\u66b4\u9732\u7684 LiveData \u662f\u53ea\u8bfb\u7684\uff0c\u9632\u6b62\u5916\u90e8\u7ec4\u4ef6\u610f\u5916\u4fee\u6539\u6570\u636e\u3002 \u901a\u8fc7\u9075\u5faa\u8fd9\u4e9b\u6700\u4f73\u5b9e\u8df5\uff0c\u4f60\u53ef\u4ee5\u5728 Android \u5e94\u7528\u4e2d\u66f4\u597d\u5730\u4f7f\u7528 LiveData\uff0c\u5b9e\u73b0\u66f4\u6e05\u6670\u3001\u53ef\u9760\u548c\u9ad8\u6548\u7684\u6570\u636e\u7ba1\u7406\u548c UI \u66f4\u65b0\u673a\u5236\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,7],"tags":[58],"class_list":["post-515","post","type-post","status-publish","format-standard","hentry","category-uncategorized","category-appdev","tag-android"],"_links":{"self":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts\/515","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=515"}],"version-history":[{"count":1,"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts\/515\/revisions"}],"predecessor-version":[{"id":516,"href":"https:\/\/trantor.ink\/index.php?rest_route=\/wp\/v2\/posts\/515\/revisions\/516"}],"wp:attachment":[{"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=515"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=515"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/trantor.ink\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=515"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}