ListView的不同item加载不同Layout

在重写ListView的BaseAdapter时，我们常常在getView()方法中复用convertView，优化ListView以提高性能。convertView在Item为单一的同种类型布局时，能够回收并重用，但是多个Item布局类型不同时，convertView的回收和重用会出现问题。比如有些行为纯文本，有些行则是图文混排，这里纯文本行为一类布局，图文混排的行为第二类布局。单一类型的ListView很简单，下面着重介绍一下ListView包含多种类型视图布局的情形，首先看图效果展示：

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在编写代码之前呢，我们需要做这些工作并了解其作用:

　　1）重写 getViewTypeCount() – 该方法返回多少个不同的布局

　　2）重写 getItemViewType(int) – 根据position返回相应的Item

　　3）根据view item的类型，在getView中创建正确的convertView

下面让我们看一下代码怎么实现：

MainActivity.class

/** *  *ListViewDifferentType * @author Yuanjunhua * * 2014-7-28下午6:23:39 */public class MainActivity extends Activity {private ListView listView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView=(ListView) findViewById(R.id.lsitview);String[] name1=new String[]{"北京","上海","南京","郑州","轻工业学院","姜寨村"};String[] name2=new String[]{"北京","上海","南京","郑州","轻工业学院","姜寨村"};Integer[] id2=new Integer[]{R.drawable.jx_left_listitem_1,R.drawable.jx_left_listitem_2,R.drawable.jx_left_listitem_3,R.drawable.jx_left_listitem_4,R.drawable.jx_left_listitem_5,R.drawable.jx_left_listitem_6};List<String> list1=new ArrayList<String>();fillListMethod(list1,name1);List<Map<String,Integer>> list2=new ArrayList<Map<String,Integer>>();fillMapMethod(list2,name2,id2);Log.d("mapList", "mapList=="+list1);Log.d("strList", "strList=="+list2);listView.setAdapter(new MyAdapter(this, list1, list2));}private void fillMapMethod(List<Map<String, Integer>> list,String[] name,Integer[] id) {// TODO Auto-generated method stubfor (int i = 0; i < name.length; i++) {Map<String,Integer> map=new HashMap<String, Integer>();map.put(name[i], id[i]);list.add(map);}}private void fillListMethod(List<String> list,String[] name) {// TODO Auto-generated method stubfor (int i = 0; i < name.length; i++) {list.add(name[i]);}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

继承BaseAdapter

/** *  *ListViewDifferentType * @author Yuanjunhua * * 2014-7-28下午6:23:31 */public class MyAdapter extends BaseAdapter {private LayoutInflater li;private List<String> list;private List<Map<String,Integer>> map;private final int TYPE_ONE=0,TYPE_TWO=1,TYPE_COUNT=2;public MyAdapter(Context context,List<String> list,List<Map<String,Integer>> map) {// TODO Auto-generated constructor stubthis.list =list;this.map =map;li=LayoutInflater.from(context);}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn list.size()+map.size();}/** 该方法返回多少个不同的布局*/@Overridepublic int getViewTypeCount() {// TODO Auto-generated method stubreturn TYPE_COUNT;}/** 根据position返回相应的Item*/@Overridepublic int getItemViewType(int position) {// TODO Auto-generated method stubint po = position % 2;if (po == TYPE_ONE)return TYPE_ONE;elsereturn TYPE_TWO;}@Overridepublic Object getItem(int position) {// TODO Auto-generated method stubreturn list.get(position%6);}@Overridepublic long getItemId(int position) {// TODO Auto-generated method stubreturn position%6;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {// TODO Auto-generated method stubViewHolder1 vh1=null;ViewHolder2 vh2=null;int type=getItemViewType(position);if(convertView==null){switch (type) {case TYPE_ONE:vh1=new ViewHolder1();convertView=li.inflate(R.layout.item_one, null);vh1.tv1=(TextView) convertView.findViewById(R.id.tv1);convertView.setTag(vh1);break;case TYPE_TWO:vh2=new ViewHolder2();convertView=li.inflate(R.layout.item_two, null);vh2.tv2=(TextView) convertView.findViewById(R.id.tv2);vh2.img2=(ImageView) convertView.findViewById(R.id.img2);convertView.setTag(vh2);break;}}else{switch (type) {case TYPE_ONE:vh1=(ViewHolder1) convertView.getTag();break;case TYPE_TWO:vh2=(ViewHolder2) convertView.getTag();break;}}switch (type) {case TYPE_ONE:if(position<5)vh1.tv1.setText(list.get((position%6)-(position%6)/2));if(position>5)vh1.tv1.setText(list.get((position%6)-(position%6)/2+3));break;case TYPE_TWO:int i=0;String txt=null;Map<String,Integer> mapSI=null;if(position<6){i=(position%6)-(position%6+1)/2;mapSI=map.get(i);Iterator<String> it=mapSI.keySet().iterator();if(it.hasNext()) txt=it.next();}if(position>6){i=(position%6)-(position%6+1)/2+3;mapSI=map.get(i);Iterator<String> it=mapSI.keySet().iterator();if(it.hasNext()) txt=it.next();}vh2.tv2.setText(txt);vh2.img2.setBackgroundResource(mapSI.get(txt));Log.d("txt", "txt=="+txt);break;}return convertView;}static class ViewHolder1{TextView tv1;}static class ViewHolder2{TextView tv2;ImageView img2;}}

实现上图的效果就用这么几句代码！！