微信中的ListView有一个特点就是存在许多不同的Item,即并不是平常的ListView,所有的Item布局都是一样的。针对这种情况,Google的Adapter提供了两个方法getItemViewType和getViewTypeCount。通过覆盖这两个方法就可以实现一个ListView中存在多种不同的Layout。实现了更加个性化的ListView效果。我归纳了下微信中的Item可以分为7中。针对这7种Item我对应地写了7中listItem。在getView的时候判断下当前数据对象中需要通过哪种布局来展现,来实时获取布局。
下面看代码:
Message.java
public class Message { private int type;//指定是哪种类型 private String value;//值 public int getType() { return type; } public void setType(int type) { this.type = type; } public String getValue() { return value; } public void setValue(String value) { this.value = value; } }
MainActivity.java:
public class MainActivity extends Activity { private ListView lvData; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); lvData = (ListView)findViewById(R.id.lv_data); lvData.setAdapter(getAdapter()); } private BaseAdapter getAdapter(){ return new MyAdapter(this, getMyData()); } private List<Message> getMyData(){ List<Message> msgList = new ArrayList<Message>(); Message msg; msg = new Message(); msg.setType(MyAdapter.VALUE_LEFT_TEXT); msg.setValue("食堂真难吃啊"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_TIME_TIP); msg.setValue("2012-12-23 下午2:23"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_RIGHT_TEXT); msg.setValue("我就说食堂的饭难吃吧,你不相信!"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_LEFT_TEXT); msg.setValue("好吧,这次听你的了。"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_TIME_TIP); msg.setValue("2012-12-23 下午2:25"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_RIGHT_TEXT); msg.setValue("就要圣诞了,有什么安排没有?"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_LEFT_TEXT); msg.setValue("没有啊,你呢?"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_TIME_TIP); msg.setValue("2012-12-23 下午3:25"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_LEFT_IMAGE); msg.setValue("7min"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_RIGHT_TEXT); msg.setValue("高帅富有三宝 木耳 跑车 和名表," + "黑木耳有三宝 美瞳 备胎 黑丝脚 ,穷矮挫有三宝 AV 手纸 射得早 ,女神有三宝 干嘛 呵呵 去洗澡 ,宅男有三宝 Dota 基友 破电脑 " + "女屌丝有三宝 虎背 熊腰 眼睛小 , 女屌丝还有三宝 饼脸 花痴 卖萌照"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_LEFT_TEXT); msg.setValue("碉堡了"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_LEFT_AUDIO); msg.setValue("7min"); msgList.add(msg); msg = new Message(); msg.setType(MyAdapter.VALUE_RIGHT_IMAGE); msg.setValue("7min"); msgList.add(msg); return msgList; } }
下面是最重要的地方:
MyAdapter.java:
public class MyAdapter extends BaseAdapter{ public static final String KEY = "key"; public static final String VALUE = "value"; public static final int VALUE_TIME_TIP = 0;//7种不同的布局 public static final int VALUE_LEFT_TEXT = 1; public static final int VALUE_LEFT_IMAGE = 2; public static final int VALUE_LEFT_AUDIO = 3; public static final int VALUE_RIGHT_TEXT = 4; public static final int VALUE_RIGHT_IMAGE = 5; public static final int VALUE_RIGHT_AUDIO = 6; private LayoutInflater mInflater; private Context context; private List<Message> myList; public MyAdapter(Context context, List<Message> myList){ this.context = context; this.myList = myList; for(Message msg:myList){ Log.d("myList:", msg.getType()+""); } mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } public void addItem(final Message item) { myList.add(item); notifyDataSetChanged(); } @Override public int getCount() { return myList.size(); } @Override public Object getItem(int arg0) { return myList.get(arg0); } @Override public long getItemId(int arg0) { return arg0; } @Override public View getView(int position, View convertView, ViewGroup arg2) { Message msg = myList.get(position); int type = getItemViewType(position); ViewHolder holder = null; if(convertView == null){ holder = new ViewHolder(); switch (type) { case VALUE_TIME_TIP: convertView = mInflater.inflate(R.layout.list_item_time_tip, null); holder.tvTimeTip = (TextView)convertView.findViewById(R.id.tv_time_tip); holder.tvTimeTip.setText(msg.getValue()); break; //左边 case VALUE_LEFT_TEXT: convertView = mInflater.inflate(R.layout.list_item_left_text, null); holder.ivLeftIcon = (ImageView)convertView.findViewById(R.id.iv_icon); holder.btnLeftText = (Button)convertView.findViewById(R.id.btn_left_text); holder.btnLeftText.setText(msg.getValue()); break; case VALUE_LEFT_IMAGE: convertView = mInflater.inflate(R.layout.list_item_left_iamge, null); holder.ivLeftIcon = (ImageView)convertView.findViewById(R.id.iv_icon); holder.ivLeftImage = (ImageView)convertView.findViewById(R.id.iv_left_image); holder.ivLeftImage.setImageResource(R.drawable.test); break; case VALUE_LEFT_AUDIO: convertView = mInflater.inflate(R.layout.list_item_left_audio, null); holder.ivLeftIcon = (ImageView)convertView.findViewById(R.id.iv_icon); holder.btnLeftAudio = (Button)convertView.findViewById(R.id.btn_left_audio); holder.tvLeftAudioTime = (TextView)convertView.findViewById(R.id.tv_left_audio_time); holder.tvLeftAudioTime.setText(msg.getValue()); break; //右边 case VALUE_RIGHT_TEXT: convertView = mInflater.inflate(R.layout.list_item_right_text, null); holder.ivRightIcon = (ImageView)convertView.findViewById(R.id.iv_icon); holder.btnRightText = (Button)convertView.findViewById(R.id.btn_right_text); holder.btnRightText.setText(msg.getValue()); break; case VALUE_RIGHT_IMAGE: convertView = mInflater.inflate(R.layout.list_item_right_iamge, null); holder.ivRightIcon = (ImageView)convertView.findViewById(R.id.iv_icon); holder.ivRightImage = (ImageView)convertView.findViewById(R.id.iv_right_image); holder.ivRightImage.setImageResource(R.drawable.test); break; case VALUE_RIGHT_AUDIO: convertView = mInflater.inflate(R.layout.list_item_right_audio, null); holder.ivRightIcon = (ImageView)convertView.findViewById(R.id.iv_icon); holder.btnRightAudio = (Button)convertView.findViewById(R.id.btn_right_audio); holder.tvRightAudioTime = (TextView)convertView.findViewById(R.id.tv_right_audio_time); holder.tvRightAudioTime.setText(msg.getValue()); break; default: break; } convertView.setTag(holder); }else{ holder = (ViewHolder)convertView.getTag(); } return convertView; } /** * 根据数据源的position返回需要显示的的layout的type * * */ @Override public int getItemViewType(int position) { Message msg = myList.get(position); int type = msg.getType(); Log.e("TYPE:", ""+type); return type; } /** * 返回所有的layout的数量 * * */ @Override public int getViewTypeCount() { return 7; } class ViewHolder{ private TextView tvTimeTip;//时间 private ImageView ivLeftIcon;//左边的头像 private Button btnLeftText;//左边的文本 private ImageView ivLeftImage;//左边的图像 private Button btnLeftAudio;//左边的声音 private TextView tvLeftAudioTime;//左边的声音时间 private ImageView ivRightIcon;//右边的头像 private Button btnRightText;//右边的文本 private ImageView ivRightImage;//右边的图像 private Button btnRightAudio;//右边的声音 private TextView tvRightAudioTime;//右边的声音时间 } }
在getView()的时候通过switch判断当前一条数据需要使用的是哪种布局,实时进行加载。
getItemViewType() 和getViewTypeCount() 这两个方法起到的作用是循环回收利用不同的布局,起到了优化的作用!这是不同于平时使用Adapter的地方。
效果如下:
项目地址: