关于Viewpager中的Fragment的生命周期

最新推荐文章于 2021-05-29 22:58:59 发布

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最新推荐文章于 2021-05-29 22:58:59 发布

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分类专栏： Android 文章标签： viewpager java 友盟

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Activity和Fragment各自理论上的生命周期

Activity的生命周期是较为经典也最清晰的，在此不表；
Fragment从出现到广泛运用也有一段时间了，其标准生命周期也仅比Activity多出一些流程，如onCreateView();

Activity和Fragment在实际编码中必定是结合出现的，表现为Activity作为容器，装载有一个或若干个Fragment；
装载多个Fragment时，经常使用TabHost和Viewpager作为载体；
在实际编码中发现，Activity和Fragment的混合情况里，其生命周期的交叉可能与预想中有差别；

使用如下方式加载Fragment时：

<div class="line"><span class="text plain"><span class="meta paragraph text"></span></span></div><div class="dp-highlighter bg_java" style="font-family: Consolas, 'Courier New', Courier, mono, serif; font-size: 12px; width: 898.90625px; overflow: hidden; padding-top: 1px; border-color: rgb(204, 204, 204); margin: 18px 0px !important; background-color: rgb(231, 229, 220);"><div class="bar" style="padding-left: 45px;"><div class="tools" style="padding: 3px 8px 10px 10px; font-stretch: normal; font-size: 9px; line-height: normal; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; color: silver; border-left-width: 3px; border-left-style: solid; border-left-color: rgb(153, 153, 153); background-color: rgb(248, 248, 248);"><strong>[java]</strong> <a target=_blank href="http://blog.youkuaiyun.com/tongcpp/article/details/41978751#" class="ViewSource" title="view plain" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;">view plain</a><a target=_blank href="http://blog.youkuaiyun.com/tongcpp/article/details/41978751#" class="CopyToClipboard" title="copy" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;">copy</a><a target=_blank href="http://blog.youkuaiyun.com/tongcpp/article/details/41978751#" class="PrintSource" title="print" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;">print</a><a target=_blank href="http://blog.youkuaiyun.com/tongcpp/article/details/41978751#" class="About" title="?" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;">?</a><a target=_blank href="https://code.youkuaiyun.com/snippets/554289" target="_blank" title="在CODE上查看代码片" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><img src="https://code.youkuaiyun.com/assets/CODE_ico.png" width="12" height="12" alt="在CODE上查看代码片" style="border: none; position: relative; top: 1px; left: 2px;" /></a><a target=_blank href="https://code.youkuaiyun.com/snippets/554289/fork" target="_blank" title="派生到我的代码片" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><img src="https://code.youkuaiyun.com/assets/ico_fork.svg" width="12" height="12" alt="派生到我的代码片" style="border: none; position: relative; top: 2px; left: 2px;" /></a><div style="position: absolute; left: 555px; top: 987px; width: 29px; height: 14px; z-index: 99;"></div></div></div><ol start="1" class="dp-j" style="padding: 0px; border: none; list-style-position: initial; list-style-image: initial; color: rgb(92, 92, 92); margin: 0px 0px 1px 45px !important; background-color: rgb(255, 255, 255);"><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">getSupportFragmentManager()  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">      .beginTransaction()  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">      .add(R.id.fragment_container, mFragment, SHARE_PUBLIC_LIST_FRAGMENT_TAG)  </span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">      .commitAllowingStateLoss();  </span></li></ol></div>
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其onResume和onPause执行过程为：

Activity - onResume
Fragment - onResume
Activity - onPause
Fragment - onPause

友盟-页面统计要求

Activity和Fragment共同体页面统计中，需要保证线性不交叉，每个onPageStart都有一个onPageEnd配对，
如：onPageStart ->onPageEnd-> onPageStart -> onPageEnd -> onPageStart ->onPageEnd
这样才能保证每个页面统计的正确。

Viewpager中Fragment的生命周期

ViewPager装载Fragment一般使用FragmentPagerAdapter或FragmentStatePagerAdapter，同样借助FragmentManager，在adapter的getItem方法中根据position制定显示的fragment
由于Viewpager的缓存特点，Viewpager启动时其第一个Fragment页面及待缓存的页面都将按顺序呢开始他们的正常生命周期，走向onResume，即：
- Viewpager所在Activity - onResume
- Fragment1 - onResume
- Fragment2 - onResume
- Fragment3 - onResume
由于这若干个页面的生命周期被同时催化了，影响了我们的单一判断，即无法判断“真正”显示和消失在使用者眼前的页面。

解决方案

方案1：设置Viewpager的缓存机制，不缓存除当前页以外的页面数据，所见即所得，离开即销毁；
此方案对需求改动较大，且较影响用户体验;

方案2：重载Fragment.onHiddenChanged(boolean hidden)方法，其参数hidden代表当前fragment显隐状态改变时，是否为隐藏状态，可通过check此参数作处理；
此方案局限在于本方法的系统调用时间发生在显隐状态改变时，但第一次显示时此方法并不调用；

方案3：重载Fragment.setUserVisibleHint(boolean isVisibleToUser)方法，其参数isVisibleToUser顾名思义最接近我们的需求，代表页面是否“真正”对使用者显示；
此方案局限在于此方法的第一次系统调用甚至早于Fragment的onCreate方法，故其第一次调用时isVisibleToUser值总为false，影响我们对生命周期顺序的判定；
- Fragment1 - isVisibleToUser - false (多余)
- Fragment1 - isVisibleToUser - true
- Fragment1 - isVisibleToUser - false
- Fragment2 - isVisibleToUser - false (多余)
- Fragment2 - isVisibleToUser - true
- Fragment2 - isVisibleToUser - false

实际采用的解决方案

根据对产品需求的理解和用户体验的统一，选择在方案3基础上加以改进；

setUserVisibleHint()方法本身很接近我们的需求，它的局限点我采取了一个侵入式的解决方式：

<div class="line"><span class="text plain"></span></div><div class="dp-highlighter bg_java" style="font-family: Consolas, 'Courier New', Courier, mono, serif; font-size: 12px; width: 898.90625px; overflow: hidden; padding-top: 1px; border-color: rgb(204, 204, 204); margin: 18px 0px !important; background-color: rgb(231, 229, 220);"><div class="bar" style="padding-left: 45px;"><div class="tools" style="padding: 3px 8px 10px 10px; font-stretch: normal; font-size: 9px; line-height: normal; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; color: silver; border-left-width: 3px; border-left-style: solid; border-left-color: rgb(153, 153, 153); background-color: rgb(248, 248, 248);"><strong>[java]</strong> <a target=_blank href="http://blog.youkuaiyun.com/tongcpp/article/details/41978751#" class="ViewSource" title="view plain" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; 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background-repeat: initial;"><img src="https://code.youkuaiyun.com/assets/CODE_ico.png" width="12" height="12" alt="在CODE上查看代码片" style="border: none; position: relative; top: 1px; left: 2px;" /></a><a target=_blank href="https://code.youkuaiyun.com/snippets/554289/fork" target="_blank" title="派生到我的代码片" style="text-decoration: none; border: none; padding: 0px; margin: 0px 10px 0px 0px; font-size: 9px; color: rgb(12, 137, 207); background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><img src="https://code.youkuaiyun.com/assets/ico_fork.svg" width="12" height="12" alt="派生到我的代码片" style="border: none; position: relative; top: 2px; left: 2px;" /></a><div style="position: absolute; left: 555px; top: 2688px; width: 29px; height: 14px; z-index: 99;"></div></div></div><ol start="1" class="dp-j" style="padding: 0px; border: none; list-style-position: initial; list-style-image: initial; color: rgb(92, 92, 92); margin: 0px 0px 1px 45px !important; background-color: rgb(255, 255, 255);"><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">protected</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">boolean</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> isCreated = </span><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">false</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">;  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="annotation" style="margin: 0px; padding: 0px; border: none; color: rgb(100, 100, 100); background-color: inherit;">@Override</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">public</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">void</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> onCreate(Bundle savedInstanceState) {  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    <span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">super</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">.onCreate(savedInstanceState);  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    <span class="comment" style="margin: 0px; padding: 0px; border: none; color: rgb(170, 202, 179); background-color: inherit;">// ...</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    isCreated = <span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">true</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">;  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">}  </span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="comment" style="margin: 0px; padding: 0px; border: none; color: rgb(170, 202, 179); background-color: inherit;">/**</span> </span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="comment" style="margin: 0px; padding: 0px; border: none; color: rgb(170, 202, 179); background-color: inherit;"> * 此方法目前仅适用于标示ViewPager中的Fragment是否真实可见</span> </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="comment" style="margin: 0px; padding: 0px; border: none; color: rgb(170, 202, 179); background-color: inherit;"> * For 友盟统计的页面线性不交叉统计需求</span> </span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="comment" style="margin: 0px; padding: 0px; border: none; color: rgb(170, 202, 179); background-color: inherit;"> */</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="annotation" style="margin: 0px; padding: 0px; border: none; color: rgb(100, 100, 100); background-color: inherit;">@Override</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">public</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> </span><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">void</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> setUserVisibleHint(</span><span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">boolean</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> isVisibleToUser) {  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    <span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">super</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">.setUserVisibleHint(isVisibleToUser);  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    <span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">if</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> (!isCreated) {  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">        <span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">return</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">;  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    }  </span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    <span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">if</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> (isVisibleToUser) {  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">        umengPageStart();  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    }<span class="keyword" style="margin: 0px; padding: 0px; border: none; color: green; font-weight: bold; background-color: inherit;">else</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;"> {  </span></span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">        umengPageEnd();  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">    }  </span></li><li style="margin: 0px !important; padding: 0px 3px 0px 10px !important; border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: rgb(119, 119, 119); line-height: 18px; background-color: rgb(249, 249, 249);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(153, 153, 153); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">}  </span></li></ol></div>
<div class="line"><span class="text plain"><span class="meta paragraph text"></span></span></div>

对onCreate方法结束的一个标记即可解决问题；
切记：此标记的改变请勿放在Fragment的onActivtyCreate方法中，此方法调用滞后于setUserVisibleHint的判断

One more thing

Viewpager装载Fragment时还有另一个坑，Viewpager的父容器（Activity或Fragment）在显隐状态改变时，如在Activity的onResume和onPause调用时，并不会主动通知Viewpager内的Fragment执行其应用的生命周期，故我们需要再增加手动强制调用两次
在Activity中查询到当前的Fragment，并执行其内方法，需要借助Viewpager，并改写其PagerAdapter；
我采用了此文提到的Second Solution：如何获得ViewPager当前显示的Fragment？