| 一、问题描述 |
本系列将结合案例应用，陆续向大家介绍一些Android典型界面的设计，首先说说tab导航，导航分为一层和两层（底部区块+区域内头部导航），主要实现方案有RadioGroup+ViewPage+Fragment、Viewpager Indicator、ActionBar Tabs、FragmentTabHost+Fragment等，下面我们先采用RadioGroup+ViewPage+Fragment实现区域头部导航。
如图所示：
| 二、案例主要组件 |
1、先看一下MainActivity布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<HorizontalScrollView
android:id="@+id/hvChannel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="none"
>
<RadioGroup
android:id="@+id/rgChannel"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:orientation="horizontal">
</RadioGroup>
</HorizontalScrollView>
<android.support.v4.view.ViewPager
android:id="@+id/vpNewsList"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
>
</android.support.v4.view.ViewPager>
</LinearLayout>
2、MainActivity代码：
public class MainActivity extends FragmentActivity implements OnPageChangeListener{
private ViewPager viewPager;
private RadioGroup rgChannel=null;
private HorizontalScrollView hvChannel;
private PageFragmentAdapter adapter=null;
private List<Fragment> fragmentList=new ArrayList<Fragment>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView(){
rgChannel=(RadioGroup)super.findViewById(R.id.rgChannel);
viewPager=(ViewPager)super.findViewById(R.id.vpNewsList);
hvChannel=(HorizontalScrollView)super.findViewById(R.id.hvChannel);
rgChannel.setOnCheckedChangeListener(
new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group,
int checkedId) {
viewPager.setCurrentItem(checkedId);
}
});
viewPager.setOnPageChangeListener(this);
initTab();//动态产生RadioButton
initViewPager();
rgChannel.check(0);
}
private void initTab(){
List<Channel> channelList=ChannelDb.getSelectedChannel();
for(int i=0;i<channelList.size();i++){
RadioButton rb=(RadioButton)LayoutInflater.from(this).
inflate(R.layout.tab_rb, null);
rb.setId(i);
rb.setText(channelList.get(i).getName());
RadioGroup.LayoutParams params=new
RadioGroup.LayoutParams(RadioGroup.LayoutParams.WRAP_CONTENT,
RadioGroup.LayoutParams.WRAP_CONTENT);
rgChannel.addView(rb,params);
}
}
private void initViewPager(){
List<Channel> channelList=ChannelDb.getSelectedChannel();
for(int i=0;i<channelList.size();i++){
NewsFragment frag=new NewsFragment();
Bundle bundle=new Bundle();
bundle.putString("weburl", channelList.get(i).getWeburl());
bundle.putString("name", channelList.get(i).getName());
frag.setArguments(bundle); //向Fragment传入数据
fragmentList.add(frag);
}
adapter=new PageFragmentAdapter(super.getSupportFragmentManager(),fragmentList);
viewPager.setAdapter(adapter);
//viewPager.setOffscreenPageLimit(0);
}
/**
* 滑动ViewPager时调整ScroollView的位置以便显示按钮
* @param idx
*/
private void setTab(int idx){
RadioButton rb=(RadioButton)rgChannel.getChildAt(idx);
rb.setChecked(true);
int left=rb.getLeft();
int width=rb.getMeasuredWidth();
DisplayMetrics metrics=new DisplayMetrics();
super.getWindowManager().getDefaultDisplay().getMetrics(metrics);
int screenWidth=metrics.widthPixels;
int len=left+width/2-screenWidth/2;
hvChannel.smoothScrollTo(len, 0);//滑动ScroollView
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageSelected(int position) {
// TODO Auto-generated method stub
setTab(position);
}
}
其中initTab（）方法实现向RadioGroup动态添加RadioButton
导航按钮数据来源于ChannelDb
private static List<Channel> selectedChannel=new ArrayList<Channel>();
static{
selectedChannel.add(new Channel("","头条",0,"",""));
selectedChannel.add(new Channel("","娱乐",0,"",""));
selectedChannel.add(new Channel("","体育",0,"",""));
selectedChannel.add(new Channel("","财经",0,"",""));
selectedChannel.add(new Channel("","热点",0,"",""));
selectedChannel.add(new Channel("","科技",0,"",""));
selectedChannel.add(new Channel("","图片",0,"",""));
selectedChannel.add(new Channel("","汽车",0,"",""));
selectedChannel.add(new Channel("","时尚",0,"",""));
}
public static List<Channel> getSelectedChannel(){
return selectedChannel;
}
导航按钮外观：tab_rb.xml和tab_selector.xml背景选择器（实现选择后带红色下划线效果）
<?xml version="1.0" encoding="utf-8"?>
<RadioButton xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:text="今日"
android:background="@drawable/tab_selector"
android:paddingLeft="15dp"
android:paddingRight="15dp"
android:paddingTop="10dp"
android:paddingBottom="10dp"
android:button="@null"
/>
tab_selector.xml:
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
<item android:state_checked="true" ><!-- 选中状态 -->
<layer-list >
<item >
<shape android:shape="rectangle">
<stroke android:width="5dp" android:color="#ff0000"/>
</shape>
</item>
<item android:bottom="5dp" >
<shape android:shape="rectangle" >
<solid android:color="#fff"/>
</shape>
</item>
</layer-list>
</item>
<item ><!-- 默认状态 -->
<shape >
<solid android:color="#FAFAFA"/>
</shape>
</item>
</selector>
3、PageFragmentAdapter适配器
public class PageFragmentAdapter extends FragmentPagerAdapter{
private List<Fragment> fragmentList;
private FragmentManager fm;
public PageFragmentAdapter(FragmentManager fm,List<Fragment> fragmentList){
super(fm);
this.fragmentList=fragmentList;
this.fm=fm;
}
@Override
public Fragment getItem(int idx) {
return fragmentList.get(idx%fragmentList.size());
}
@Override
public int getCount() {
return fragmentList.size();
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE; //没有找到child要求重新加载
} }
4、NewsFragment组件：
public class NewsFragment extends Fragment {
private String weburl;
private String channelName;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
private View view;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(view==null){//优化View减少View的创建次数
//该部分可通过xml文件设计Fragment界面，再通过LayoutInflater转换为View组件
//这里通过代码为fragment添加一个TextView
TextView tvTitle=new TextView(getActivity());
tvTitle.setText(channelName);
tvTitle.setTextSize(16);
tvTitle.setGravity(Gravity.CENTER);
tvTitle.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT));
view=tvTitle;
}
ViewGroup parent=(ViewGroup)view.getParent();
if(parent!=null){//如果View已经添加到容器中，要进行删除，负责会报错
parent.removeView(view);
}
return view;
}
@Override
public void setArguments(Bundle bundle) {//接收传入的数据
weburl=bundle.getString("weburl");
channelName=bundle.getString("name");
}
}
想要了解更多内容的小伙伴，可以点击查看源码，亲自运行测试。
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作者：杰瑞教育
出处：http://blog.csdn.net/jerehedu/
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时间： 2025-01-18 01:48:08