京东手机端的类别标签页, 是一个左侧滑动可选择类别, 右侧一个类别明细的列表联动页面. 当用户选择左侧选项, 可在右侧显示更多选项来选择. 实现方式也不少. 最常见的当然是左侧和右侧各一个Fragment, 左侧Fragment放置ListView, 右侧放显示类别明细的Fragment. 如果觉得页面包含的Fragment太多, 左侧直接给一个ListView就可以了.不影响效果.
效果图:
例子中值得注意的三点:
针对上面三个点,这里采取如下的解决方法:
重在通过简单的例子解释这种实现思路, 当然实现不是唯一的.
然后,我们先来模拟右侧的Fragment数据,一看就懂的代码:
public class JDFragment extends Fragment{ String TAG = "JDFragment"; private View rootView = null; private LinearLayout llayout_main = null; private TextView tv = null; private LinearLayout.LayoutParams lp_gd = null; private LinearLayout.LayoutParams lp_tv = null; private ArrayList<Category> itemList = null; private GDAdapter adapter = null; @Override public void onAttach(Activity activity) { Log.e(TAG, "onAttach..."); super.onAttach(activity); } @Override public void onCreate(Bundle savedInstanceState) { Log.e(TAG, "onCreate..."); super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { Log.e(TAG, "onCreateView..."); rootView = inflater.inflate(R.layout.jd_frg_main, null); llayout_main = (LinearLayout) rootView.findViewById(R.id.llayout_jd_frg_main); tv = (TextView) rootView.findViewById(R.id.tv_jd_frg_main); updateTitle(); //模拟数据 for(int i=0; i<2; i++) { setData(); } return rootView; } protected void updateTitle() { if(getArguments() != null) { updateTitle(getArguments().getString("name")); } } protected void updateTitle(String title) { if(tv != null) { tv.setText(title); } } private void setData() { if(itemList == null) { itemList = new ArrayList<Category>(); for(int i=1; i<11; i++) { itemList.add(new Category("选项 " + i, ""+i)); } } //高度60dp+行距8dp = 68dp int heightUnit = (int)TypedValue .applyDimension(TypedValue.COMPLEX_UNIT_DIP, 68, getResources().getDisplayMetrics()); int height; //计算Gridview总高度 if(itemList.size() % 3 == 0) { height = (itemList.size()/3 + 2)*heightUnit; } else{ height = (itemList.size()/3 + 1)*heightUnit; } if(lp_gd == null) lp_gd = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, height); if(lp_tv == null) lp_tv = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT , (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP , 30, getResources().getDisplayMetrics())); TextView tv_title = new TextView(getActivity()); tv_title.setLayoutParams(lp_tv); tv_title.setText("组一"); llayout_main.addView(tv_title); GridView gridView = new GridView(getActivity()); gridView.setNumColumns(3); gridView.setVerticalSpacing(8); gridView.setLayoutParams(lp_gd); adapter = new GDAdapter(getActivity(), itemList,R.drawable.cate); gridView.setAdapter(adapter); llayout_main.addView(gridView); } @Override public void onActivityCreated(Bundle savedInstanceState) { Log.e(TAG, "onActivityCreated..."); super.onActivityCreated(savedInstanceState); } @Override public void onStart() { Log.e(TAG, "onStart..."); super.onStart(); } @Override public void onResume() { Log.e(TAG, "onResume..."); super.onResume(); } @Override public void onPause() { Log.e(TAG, "onPause..."); super.onPause(); } @Override public void onStop() { Log.e(TAG, "onStop..."); super.onStop(); } @Override public void onDestroyView() { Log.e(TAG, "onDestroyView..."); super.onDestroyView(); } @Override public void onDestroy() { Log.e(TAG, "onDestroy..."); super.onDestroy(); } @Override public void onDetach() { Log.e(TAG, "onDetach..."); super.onDetach(); } static class GDAdapter extends BaseAdapter { Context context; List<Category> results; int imageId; ViewHolder holder = null; public GDAdapter(Context context, List<Category> results,int imageId) { this.context = context; this.results = results; this.imageId = imageId; } @Override public int getCount() { // TODO Auto-generated method stub return results.size(); } @Override public Object getItem(int position) { // TODO Auto-generated method stub return results.get(position); } @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { Category c = (Category)getItem(position); if(convertView == null) { holder = new ViewHolder(); convertView = LayoutInflater.from(context).inflate(R.layout.jd_item, null); holder.tv = (TextView) convertView.findViewById(R.id.tv_jd_item); holder.imv = (ImageView) convertView.findViewById(R.id.imv_jd_item); } else { holder = (ViewHolder) convertView.getTag(); } convertView.setTag(holder); holder.tv.setText(c.getName()); holder.imv.setImageResource(imageId); return convertView; } class ViewHolder { TextView tv; ImageView imv; } }}JDFragment的布局文件, jd_frg_main.xml:
<?xml version="1.0" encoding="utf-8" ?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFFFFF" > <TextView android:id="@+id/tv_jd_frg_main" android:layout_width="match_parent" android:layout_height="25dp" android:text="Fragment" android:textSize="16sp" android:background="#EEEEEE" /> <ScrollView android:id="@+id/scrlayout_jd_frg_main" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@+id/tv_jd_frg_main" android:overScrollMode="never" > <LinearLayout android:id="@+id/llayout_jd_frg_main" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" /> </ScrollView></RelativeLayout>
将所有数据放在ScrollView的线性布局中,使用Fragment作为容器, 可以根据需要ADD, Remove和Update数据和View. 到这里右侧页面的简单模拟实现就结束了,都是一目了然的代码.
然后就是实现左侧列表了,先是列表中简单的自定义Adapter, MyAdapter:
public class MyAdapter extends BaseAdapter{ private Context context; private List<Category> results; private int imageId; private ViewHolder holder = null; private int selectedId; public MyAdapter(Context context, List<Category> results,int imageId) { this.context = context; this.results = results; this.imageId = imageId; } @Override public int getCount() { // TODO Auto-generated method stub return results.size(); } @Override public Object getItem(int position) { // TODO Auto-generated method stub return results.get(position); } @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } public void setSelected(int position) { this.selectedId = position; } @Override public View getView(int position, View convertView, ViewGroup parent) { Category c = (Category)getItem(position); if(convertView == null) { holder = new ViewHolder(); convertView = LayoutInflater.from(context).inflate(R.layout.jd_item, null); holder.tv = (TextView) convertView.findViewById(R.id.tv_jd_item); holder.imv = (ImageView) convertView.findViewById(R.id.imv_jd_item); } else { holder = (ViewHolder) convertView.getTag(); } if(position == selectedId) { convertView.setBackgroundResource(R.drawable.sele_true); } else { convertView.setBackgroundResource(R.drawable.sele_false); } holder.tv.setText(c.getName()); holder.imv.setImageResource(imageId); convertView.setTag(holder); return convertView; } class ViewHolder { TextView tv; ImageView imv; }}然后是主Activity了, 在里面对可见ListView的item位置进行计算, 并进行滑动处理. 当用户点击偏上的item, 列表就往下滑动, 加载顶部更多的item; 当用户点击偏下的item, 列表就往上滑动, 加载底部更多的item.
同时我们自定义按下和松开时的背景文件放在drawable, 随便一个shape就可以了. 然后点击某个item的position时, 在adapter中判断是否目标item, 是就设置按下背景色 - 白色, 否则就是正常的背景色 - 灰色.
/** * 仿京东类别页 * @author AlexTam */public class JDActivity extends FragmentActivity{ private ListView lv_main = null; private EditText et_search = null; private ArrayList<Category> itemList = new ArrayList<Category>(); private MyAdapter adapter = null; //可见列表项的数量 private int visibleCount = 0; //上次点击的位置 private int lastPosition = 0; private int ce = 0; //实际列表是否超出屏幕 private boolean isOut = true; private JDFragment fragment = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.jd_main); init(); } private void init() { lv_main = (ListView) findViewById(R.id.lv_main); et_search = (EditText) findViewById(R.id.et_search); for(int i=1; i<21; i++) { itemList.add(new Category("选项 " + i, ""+i)); } adapter = new MyAdapter(this, itemList,R.drawable.ic_launcher); lv_main.setAdapter(adapter); lv_main.setOnItemClickListener(new MyOnItemOnClick()); lv_main.setSelector(R.color.pink); //模拟右侧标签页 fragment = new JDFragment(); Bundle bundle = new Bundle(); bundle.putString("name", "c1"); fragment.setArguments(bundle); FragmentManager fm = getSupportFragmentManager(); FragmentTransaction ft = fm.beginTransaction(); ft.replace(R.id.flayout_main, fragment, "c0").commit(); adapter.setSelected(0); adapter.notifyDataSetChanged(); } private class MyOnItemOnClick implements OnItemClickListener { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { //计算滑动 if(visibleCount == 0) { visibleCount = lv_main.getChildCount(); if(visibleCount == itemList.size()) isOut = false; else { ce = visibleCount/2; } } if(position <= (parent.getFirstVisiblePosition() + ce)) { //上移 lv_main.smoothScrollToPosition(position - ce); } else { //下移 if((parent.getLastVisiblePosition() + ce + 1) <= parent.getCount()) { lv_main.smoothScrollToPosition(position + ce); } else { lv_main.smoothScrollToPosition(parent.getCount()-1); } } lastPosition = position; adapter.setSelected(position); adapter.notifyDataSetChanged(); //更新右侧标签页的标题 fragment.updateTitle("c" + (position+1)); } } /** * 选项对象 */ static class Category { private String name; private String id; Category(String name,String id) { this.name = name; this.id = id; } public String getName() { return this.name; } }}OK, 到此效果就出来了. 好简单吧!
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