运行上述代码及可以看到如下效果图
使用RadioGroup和RadioButton实现仿qq底部切换
第一步 ，先看布局文件
<?xml version="1.0" encoding="utf-8"?><LinearLayout
android:id="@+id/activity_second_style"
xmlns:android=“http://schemas.android.com/apk/res/android”
android:layout_width=“match_parent”
android:layout_height=“match_parent”
android:orientation=“vertical”
<FrameLayout
android:id="@+id/fl"
android:layout_width=“match_parent”
android:layout_height=“0dp”
android:layout_weight=“1”>
<RadioGroup
android:id="@+id/rg"
android:layout_width=“match_parent”
android:layout_height=“wrap_content”
android:orientation=“horizontal”
<RadioButton
android:id="@+id/rb_home"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_home"
android:text=“首页”/>
<RadioButton
android:id="@+id/rb_course"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_course"
android:text=“课程”/>
<RadioButton
android:id="@+id/rb_direct_seeding"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_direct_seeding"
android:text=“直播”/>
<RadioButton
android:id="@+id/rb_me"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_me"
android:text=“我的”/>
其实每一个tab的选中时利用RadioGroup中RadioButton的互相排斥的特性，即每一次只能选中一个 RadioButton
至于bottom_tab的style，只不过是将相同的arr提取出来，减少布局的代码量和方便统一修改而已，平时我们在写布局代码 的时候也可以这样
第二步，我们来看一下Activity的 代码
public class ThreeActivity extends AppCompatActivity {
FrameLayout mFl;
RadioGroup mRg;
private FragmentManager mFragmentManager;
private int position = 0;
public static final String[] mTiltles = new String[]{
“首页”, “课程”, “直播”, “个人”
};
private List mFragments;
private Fragment mCurFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_three);
mFl = (FrameLayout) findViewById(R.id.fl);
mRg = (RadioGroup) findViewById(R.id.rg);
mFragments = new ArrayList<>();
for (int i = 0; i < mTiltles.length; i++) {
ItemFragement itemFragement = ItemFragement.newInstance(mTiltles[i]);
mFragments.add(itemFragement);
}
mCurFragment = mFragments.get(position);
replaceFragment(mCurFragment);
((RadioButton)mRg.getChildAt(position)).setChecked(true);
initListener();
}
private void initListener() {
mRg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
RadioButton radioButton = (RadioButton) group.findViewById(checkedId);
if (false == radioButton.isChecked()) {
return;
}
switch (checkedId) {
case R.id.rb_home:
position = 0;
break;
case R.id.rb_course:
position = 1;
break;
case R.id.rb_direct_seeding:
position = 2;
break;
case R.id.rb_me:
position = 3;
break;
default:
position = 0;
break;
}
LUtils.i(“position==” + position);
Fragment to = mFragments.get(position);
showFragment(mCurFragment, to);
mCurFragment = to;
}
});
}
private void showFragment(Fragment from, Fragment to) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = supportFragmentManager.beginTransaction();
if (!to.isAdded()) { // 先判断是否被add过
transaction.hide(from).add(R.id.fl, to).commit(); // 隐藏当前的fragment，add下一个到Activity中
} else {
transaction.hide(from).show(to).commit(); // 隐藏当前的fragment，显示下一个
}
}
/**
-
这个方法用老替换fragment
-
xujun
-
2016/5/3 17:28.
*/
private void replaceFragment(Fragment fragmeny) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fl, fragmeny).commit();
}
}
思路解析
-
实例化各个控件，这里代码就不贴出来了
-
初始化 Fragemnt 和选中各个tab
mFragments = new ArrayList<>();
for (int i = 0; i < mTiltles.length; i++) {
ItemFragement itemFragement = ItemFragement.newInstance(mTiltles[i]);
mFragments.add(itemFragement);
}
mCurFragment = mFragments.get(position);
replaceFragment(mCurFragment);
((RadioButton)mRg.getChildAt(position)).setChecked(true);
private void replaceFragment(Fragment fragmeny) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fl, fragmeny).commit();
}
- 第三步，通过监听RadioGroup的 OnCheckedChangeListener事件，来实现tab和Fragemnt的切换
mRg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
RadioButton radioButton = (RadioButton) group.findViewById(checkedId);
if (false == radioButton.isChecked()) {
return;
}
switch (checkedId) {
case R.id.rb_home:
position = 0;
break;
case R.id.rb_course:
position = 1;
break;
case R.id.rb_direct_seeding:
position = 2;
break;
case R.id.rb_me:
position = 3;
break;
default:
position = 0;
break;
}
LUtils.i(“position==” + position);
Fragment to = mFragments.get(position);
showFragment(mCurFragment, to);
mCurFragment = to;
}
});
使用RadioGroup和ViewPager 实现可以滑动切换的仿qq底部Tab切换
第一步，我们 同样先看布局代码
<?xml version="1.0" encoding="utf-8"?><LinearLayout
android:id="@+id/activity_second_style"
xmlns:android=“http://schemas.android.com/apk/res/android”
android:layout_width=“match_parent”
android:layout_height=“match_parent”
android:orientation=“vertical”
<android.support.v4.view.ViewPager
android:id="@+id/viewPager"
android:layout_width=“match_parent”
android:layout_height=“0dp”
android:layout_weight=“1”>
</android.support.v4.view.ViewPager>
<RadioGroup
android:id="@+id/rg"
android:layout_width=“match_parent”
android:layout_height=“wrap_content”
android:orientation=“horizontal”
<RadioButton
android:id="@+id/rb_home"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_home"
android:text=“首页”/>
<RadioButton
android:id="@+id/rb_course"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_course"
android:text=“课程”/>
<RadioButton
android:id="@+id/rb_direct_seeding"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_direct_seeding"
android:text=“直播”/>
<RadioButton
android:id="@+id/rb_me"
style="@style/bottom_tab"
android:drawableTop="@drawable/sel_me"
android:text=“我的”/>
第二步，我们一起来看一下Activity代码
public class SecondStyleActivity extends AppCompatActivity {
public static final String[] mTiltles = new String[]{
“首页”, “课程”, “直播”, “个人”
};
private List mFragments;
ViewPager mViewPager;
RadioGroup mRg;
pr
《Android学习笔记总结+最新移动架构视频+大厂安卓面试真题+项目实战源码讲义》
【docs.qq.com/doc/DSkNLaERkbnFoS0ZF】 完整内容开源分享
ivate int position = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second_style);
mViewPager = (ViewPager) findViewById(R.id.viewPager);
mRg = (RadioGroup) findViewById(R.id.rg);
initListener();
initData();
}
private void initData() {
mFragments = new ArrayList<>();
for (int i = 0; i < mTiltles.length; i++) {
ItemFragement itemFragement = ItemFragement.newInstance(mTiltles[i]);
mFragments.add(itemFragement);
}
BaseFragmentAdapter fragmentAdapter = new BaseFragmentAdapter
(getSupportFragmentManager(), mFragments, mTiltles);
mViewPager.setAdapter(fragmentAdapter);
mViewPager.setCurrentItem(position);
((RadioButton) mRg.getChildAt(position)).setChecked(true);
}
private void initListener() {
mViewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
RadioButton radioButton = (RadioButton) mRg.getChildAt(position);
radioButton.setChecked(true);
}
});
mRg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
RadioButton rb = (RadioButton) group.findViewById(checkedId);
if (!rb.isChecked()) {
return;
}
switch (checkedId) {
case R.id.rb_home:
position = 0;
break;
case R.id.rb_course:
position = 1;
break;
case R.id.rb_direct_seeding:
position = 2;
break;
case R.id.rb_me:
position = 3;
break;
default:
position = 0;
break;
}
mViewPager.setCurrentItem(position);
}
});
}
}
思路解析如下
- 实例化ViewPager和RadioGroup
mViewPager = (ViewPager) findViewById(R.id.viewPager);
mRg = (RadioGroup) findViewById(R.id.rg);
- 第二步，初始化ViewPager的适配器和选中 那个tab
mFragments = new ArrayList<>();
for (int i = 0; i < mTiltles.length; i++) {
ItemFragement itemFragement = ItemFragement.newInstance(mTiltles[i]);
mFragments.add(itemFragement);
}
BaseFragmentAdapter fragmentAdapter = new BaseFragmentAdapter
(getSupportFragmentManager(), mFragments, mTiltles);
mViewPager.setAdapter(fragmentAdapter);
mViewPager.setCurrentItem(position);
((RadioButton) mRg.getChildAt(position)).setChecked(true);
- 第三步，监听ViewPager 的滑动事件和RadioGroup的OnCheckedChangeListener事件，分别切换到相应的 Fragemnt 和同步ViewPager中 position 与RadioGroup之间的联系
mViewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
RadioButton radioButton = (RadioButton) mRg.getChildAt(position);
radioButton.setChecked(true);
}
});
mRg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
RadioButton rb = (RadioButton) group.findViewById(checkedId);
if (!rb.isChecked()) {
return;
}
switch (checkedId) {
case R.id.rb_home:
position = 0;
break;
case R.id.rb_course:
position = 1;
break;
case R.id.rb_direct_seeding:
position = 2;
break;
case R.id.rb_me:
position = 3;
break;
default:
position = 0;
break;
}
mViewPager.setCurrentItem(position);
}
});
注意事项
我们可以通过以下方法设置ViewPager左右页面 能缓存的fragment 数量
// 设置左右页面 能缓存的fragment 数量
mViewPager.setOffscreenPageLimit(fragmentAdapter.getCount() - 1);
到此仿qq底部tab切换的集中方法已经讲解完毕，之所以讲解了 三种方法，是想让大家了解多种实现方式，因为每一个人的习惯都不一样，有些人习惯使用与第一种方式，有人习惯使用第二种方式 。。。。。。了解多种 实现方式以后，我们要读懂别人的代码也容易得多了，其实我们还可以使用自定义控件来实现，方法也比较简单，这里就不讲解了，有兴趣的话，可以自行搜索
下面我将为大家讲解Fragment的 一些优化
解决Fragment多次实例化的几种方案
目前本人了解到的解决方案 ，无非是利用一下两种思想
第一种解决方法
在onCreateView中避免多次实例化View，可通过判断View是否为空，来实现相应的 逻辑操作,核心代码如下
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable
Bundle savedInstanceState) {
LUtils.i(getClass().getSimpleName()+">>>>>>>>>>> onCreateView");
if(mView==null){
mContext = getContext();
mView=View.inflate(mContext,getLayoutId(),null);
initView(mView);
LUtils.i(getClass().getSimpleName()+">>>>>>>>>>> initView");
}else{
// 缓存的rootView需要判断是否已经被加过parent，如果有parent需要从parent删除，
// 要不然会发生这个rootview已经有parent的错误。
ViewGroup parent =(ViewGroup) mView.getParent();
if(parent!=null){
parent.removeView(mView);
}
LUtils.i(getClass().getSimpleName()+">>>>>>>>>>> removeView");
}
return mView;
}
第二种解决方案
在项目中需要进行Fragment的切换，用hide（）和show（）方法结合起来来替代replace()方法来实现Fragment的切换：
private void showFragment(Fragment from, Fragment to) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = supportFragmentManager.beginTransaction();
if (!to.isAdded()) { // 先判断是否被add过
transaction.hide(from).add(R.id.fl, to).commit(); // 隐藏当前的fragment，add下一个到Activity中
} else {
transaction.hide(from).show(to).commit(); // 隐藏当前的fragment，显示下一个
}
}
/**
-
这个方法用老替换fragment
-
xujun
-
2016/5/3 17:28.
*/
private void replaceFragment(Fragment fragmeny) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fl, fragmeny).commit();
}
关于 避免Fragment的多次实例化的分析与优化到此为止，下面我们一起来看一下 则那样实现Fragemnt 的 懒加载
Fragemnt的懒加载（网上很多人称之为Fragemnt的最优加载）
关于懒加载的这部分，代码是参考这篇 博客的 ViewPager+Fragment LazyLoad最优解
我们知道 ViewPager通常 会有预加载机制，默认情况下会先加载左右一页的数据，有时候我们想等待页面可见的时候在去加载网络 数据 ，解决方案如下
下面 先贴出代码
public abstract class BasePageFragment extends Fragment {
protected View mView;
/**
- 表示View是否被初始化
*/
protected boolean isViewInitiated;
/**
- 表示对用户是否可见
*/
protected boolean isVisibleToUser;
/**
- 表示数据是否初始化
*/
protected boolean isDataInitiated;
private Context mContext;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> onCreate”);
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable
Bundle savedInstanceState) {
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> onCreateView”);
if (mView == null) {
mContext = getContext();
mView = View.inflate(mContext, getLayoutId(), null);
initView(mView);
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> initView”);
} else {
// 缓存的rootView需要判断是否已经被加过parent，如果有parent需要从parent删除，
// 要不然会发生这个rootview已经有parent的错误。
ViewGroup parent = (ViewGroup) mView.getParent();
if (parent != null) {
parent.removeView(mView);
}
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> removeView”);
}
return mView;
}
protected abstract void initView(View view);
protected abstract int getLayoutId();
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> onActivityCreated”);
isViewInitiated = true;
initData();
prepareFetchData();
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
s().getSimpleName() + “>>>>>>>>>>> onCreate”);
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable
Bundle savedInstanceState) {
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> onCreateView”);
if (mView == null) {
mContext = getContext();
mView = View.inflate(mContext, getLayoutId(), null);
initView(mView);
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> initView”);
} else {
// 缓存的rootView需要判断是否已经被加过parent，如果有parent需要从parent删除，
// 要不然会发生这个rootview已经有parent的错误。
ViewGroup parent = (ViewGroup) mView.getParent();
if (parent != null) {
parent.removeView(mView);
}
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> removeView”);
}
return mView;
}
protected abstract void initView(View view);
protected abstract int getLayoutId();
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
LUtils.i(getClass().getSimpleName() + “>>>>>>>>>>> onActivityCreated”);
isViewInitiated = true;
initData();
prepareFetchData();
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);