author by afei
利用 android-support-v4 中的ViewPager可以轻松的实现跟手滑动。但是只支持 View 和 Fragment(也是利用view)。
之前也考虑过使用 ViewFliping 和 gallery ,但是都要将Activity转成View才可以。但是这样就会失去activity的特性。思来想后,还是改成Fragment靠谱点。
总体思路是这样:将本来放在TabActivity中的Activity们都改成 Fragment, 然后修改TabActivity,使其TabHost中content和width和height为0,然后把pager和tabHost关联起来。很trick。。。但是效果达到。
关键是如何修改activity至fragment,有没有这个可行性?
答案是必须应该可以的!万一有问题,也是可以商量的嘛。。。
1.将 extends Activity 改为 extends Fragment, 如果是 ListActivity 就改为 ListFragment。。。这明显就是为了修改方便啊。。。
2.一定会有XX出现,但是一定不多,fragment 的生命周期和 activity 很相似,包括onActivityResult() onStart() onPause() 等等。都有。
这里主要在onCreate()中,因为我们onCreate() 中会有 setContent(R.layout.layout_id) 恩,这里一定会报错,因为在fragment中单独抽出来了一个函数 onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState),把跟初始化view的相关代码都考到这个函数中就ok了,简单啊。将setContent 变为 inflater.inflate(R.layout.choose_accompany_layout, null) 然后return就ok。
3.最后一步,我们的代码中会有一些用到activity 和context 的地方,比如 getContentResolver() 和 其它的函数,这里只需要变为 getActivity() 就ok。因为fragment 中会和 外界的activity绑定起来。直接调用就可以。
修改完毕!!!
继承 FragmentTabsPager(代码在ChannelCommon中), 在onCreate()中调用 addTab(), 需要几个tab页就加入几次,然后这可以完美实现跟手滑动的tabActivity效果了!!!哇哈哈。
FragmentTabsPager 代码 :
/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.xiaomi.channel.common.pager_tabs; import android.content.Context; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.view.View; import android.view.ViewGroup; import android.widget.TabHost; import android.widget.TabWidget; import java.util.ArrayList; import com.xiaomi.channel.common.R; /** * 经过afei修改为抽象类,使用者只需要继承它,并在onCreate() 中调用addTab即可 addTab 时的tabSpec * 可以使用布局,无需担心。可见UsageDemo * Demonstrates combining a TabHost with a ViewPager to * implement a tab UI that switches between tabs and also allows the user to * perform horizontal flicks to move between the tabs. */ public abstract class FragmentTabsPager extends FragmentActivity { TabHost mTabHost; ViewPager mViewPager; TabsAdapter mTabsAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.fragment_tabs_pager); mTabHost = (TabHost) findViewById(android.R.id.tabhost); mTabHost.setup(); mViewPager = (ViewPager) findViewById(R.id.pager); mTabsAdapter = new TabsAdapter(this, mTabHost, mViewPager); } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putString("tab", mTabHost.getCurrentTabTag()); } /** * This is a helper class that implements the management of tabs and all * details of connecting a ViewPager with associated TabHost. It relies on a * trick. Normally a tab host has a simple API for supplying a View or * Intent that each tab will show. This is not sufficient for switching * between pages. So instead we make the content part of the tab host 0dp * high (it is not shown) and the TabsAdapter supplies its own dummy view to * show as the tab content. It listens to changes in tabs, and takes care of * switch to the correct paged in the ViewPager whenever the selected tab * changes. */ public static class TabsAdapter extends FragmentPagerAdapter implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener { private final Context mContext; private final TabHost mTabHost; private final ViewPager mViewPager; private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>(); static final class TabInfo { private final String tag; private final Class<?> clss; private final Bundle args; TabInfo(String _tag, Class<?> _class, Bundle _args) { tag = _tag; clss = _class; args = _args; } } static class DummyTabFactory implements TabHost.TabContentFactory { private final Context mContext; public DummyTabFactory(Context context) { mContext = context; } @Override public View createTabContent(String tag) { View v = new View(mContext); v.setMinimumWidth(0); v.setMinimumHeight(0); return v; } } public TabsAdapter(FragmentActivity activity, TabHost tabHost, ViewPager pager) { super(activity.getSupportFragmentManager()); mContext = activity; mTabHost = tabHost; mViewPager = pager; mTabHost.setOnTabChangedListener(this); mViewPager.setAdapter(this); mViewPager.setOnPageChangeListener(this); } public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) { tabSpec.setContent(new DummyTabFactory(mContext)); String tag = tabSpec.getTag(); TabInfo info = new TabInfo(tag, clss, args); mTabs.add(info); mTabHost.addTab(tabSpec); notifyDataSetChanged(); } @Override public int getCount() { return mTabs.size(); } @Override public Fragment getItem(int position) { TabInfo info = mTabs.get(position); return Fragment.instantiate(mContext, info.clss.getName(), info.args); } @Override public void onTabChanged(String tabId) { int position = mTabHost.getCurrentTab(); mViewPager.setCurrentItem(position); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { // Unfortunately when TabHost changes the current tab, it kindly // also takes care of putting focus on it when not in touch mode. // The jerk. // This hack tries to prevent this from pulling focus out of our // ViewPager. TabWidget widget = mTabHost.getTabWidget(); int oldFocusability = widget.getDescendantFocusability(); widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS); mTabHost.setCurrentTab(position); widget.setDescendantFocusability(oldFocusability); } @Override public void onPageScrollStateChanged(int state) { } } }
这是个通用的类,使用时继承就ok了,比如这样:
package com.xiaomi.channel.common.pager_tabs; import android.os.Bundle; public class UsageDemo extends FragmentTabsPager { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // 只需要将下面注释取消就可以,也就是说,只需要重写onCreate(),并加入tab就ok了。 // 每一行是一个TabSpec。记的要是Fragment,而不是activity mTabsAdapter.addTab(mTabHost.newTabSpec("simple").setIndicator("Simple"), ChooseAccompanyFragment.class, null); mTabsAdapter.addTab(mTabHost.newTabSpec("contacts").setIndicator("Contacts"), ChooseAccompanyFragment1.class, null); mTabsAdapter.addTab(mTabHost.newTabSpec("custom").setIndicator("Custom"), ChooseAccompanyFragment2.class, null); mTabsAdapter.addTab(mTabHost.newTabSpec("throttle").setIndicator("Throttle"), ChooseAccompanyFragment3.class, null); } }
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