新浪微博随便看看
【分析】
其实这个小画面是很简单的：
1.自定义适配器的书写
2.实体类的编写
3.ListView及ListView_Item
4.ListView的绑定数据源与控件
代码：
1.第一个就是自定义适配器MyAdapter:
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package cn.edu.bzu.adapter; import java.util.List; import cn.edu.bzu.entity.Information; import cn.edu.bzu.weibo_looking.R; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.TextView; /** * 自定义Adapter实现listView的显示 * @author monster * @date : 2015-04-28 */public class MyAdapter extends BaseAdapter { private List<Information> list; private Context mContext; private LayoutInflater mInflater; //定义构造方法 public MyAdapter(List<Information> list, Context mContext) { super(); this.list = list; this.mContext = mContext; } @Override public int getCount() { return list.size(); } @Override public Object getItem(int position) { return list.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder holder=null; if(convertView==null){ convertView=mInflater.from(mContext).inflate(R.layout.listview_item,null); //布局转换成视图 holder=new ViewHolder(); //实例化控件 holder.Image=(ImageView)convertView.findViewById(R.id.Iv); holder.Name=(TextView)convertView.findViewById(R.id.Name); holder.Time=(TextView)convertView.findViewById(R.id.Time); holder.Contents=(TextView)convertView.findViewById(R.id.Contents); convertView.setTag(holder); //设置setTag使得程序得以优化 }else{ holder=(ViewHolder) convertView.getTag(); } //给控件赋值 holder.Image.setBackgroundResource(list.get(position).getImgId()); holder.Name.setText(list.get(position).getName()); holder.Time.setText(list.get(position).getDate()); holder.Contents.setText(list.get(position).getContent()); return convertView; } class ViewHolder{ ImageView Image; TextView Name; TextView Time; TextView Contents; } } |
2.然后就是MainActivity的编写
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package cn.edu.bzu.weibo_looking; import java.util.ArrayList; import java.util.List; import cn.edu.bzu.adapter.MyAdapter; import cn.edu.bzu.entity.Information; import android.os.Bundle; import android.widget.ListView; import android.app.Activity; public class MainActivity extends Activity { private ListView listView; private MyAdapter adapter; private List<Information> list; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); setData();//数据源 initView(); } private void initView() { // 初始化控件 listView=(ListView) findViewById(R.id.Lv); listView.setAdapter(adapter); //绑定适配器 } private void setData() { // 设置数据源 list=new ArrayList<Information>(); list.add(new ListCell(R.drawable.p1, "强强", "1分钟前", "今天又要去旅游了")); adapter=new MyAdapter(list, MainActivity.this); } } |
Ps：在书写MainActivity的时候：一定要记住这些东西
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CommonAdapter.java：
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package cn.edu.bzu.util; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; import java.util.List; import cn.edu.bzu.weibo_looking.R; /** * CommonAdapter makes Common extends BaseAdapter * Created by monster on 2015/5/3. */public abstract class CommonAdapter<T> extends BaseAdapter { protected Context mContext; protected List<T> mDatas; protected LayoutInflater mInflater; public CommonAdapter(Context context,List<T>datas){ this.mContext=context; this.mDatas=datas; mInflater=LayoutInflater.from(context); } @Override public int getCount() { return mDatas.size(); } @Override public T getItem(int position) { return mDatas.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent){ ViewHolder holder=ViewHolder.get(mContext,convertView,parent, R.layout.listview_item,position); convert(holder,getItem(position)); return holder.getConvertView(); } public abstract void convert(ViewHolder holder,T t); } |
ViewHolder.java:
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package cn.edu.bzu.util; import android.content.Context; import android.util.SparseArray; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ImageView; import android.widget.TextView; /** * Created by monster on 2015/4/20. * Have a good package ViewHolder * get(Context context,View convertView,ViewGroup parent,int layoutId,int position) To make ViewHolder * */public class ViewHolder { private SparseArray<View> mViews; //稀疏数组，SparseArray比HashMap执行效率高 private int mPosition; private View mConvertView; //作用是方便系统在重写UI时，能重用原来实用过的View实例，以此来降低系统资源的消耗和提高代码效率 /* *ConvertView的几点特征。 *对于一个ListView，Android保存所有曾经生成过的ConvertView实例，直至系统垃圾回收这些实例位置，而不是只保存最后使用的ConvertView对象。 *这些保存的ConvertView以使用时间顺序排序，并依次被传递到getView函数中。 */ public ViewHolder(Context context,ViewGroup parent,int layoutId,int position){ //ViewHolder的构造方法 this.mPosition=position; this.mViews=new SparseArray<View>(); //初始化SparseArray对象 mConvertView= LayoutInflater.from(context).inflate(layoutId,parent,false); mConvertView.setTag(this); } public static ViewHolder get(Context context,View convertView,ViewGroup parent,int layoutId,int position){ if(convertView==null){ return new ViewHolder(context,parent,layoutId,position); }else{ ViewHolder holder=(ViewHolder)convertView.getTag(); holder.mPosition=position; return holder; } } /** * 通过viewId获取控件 * @param viewId * @param <T> * @return */ public <T extends View> T getView(int viewId){ View view=mViews.get(viewId); if(view==null){ view=mConvertView.findViewById(viewId); mViews.put(viewId,view); } return (T)view; } public View getConvertView() { return mConvertView; } /** * 为设置TextView的值 * @param viewId * @param text * @return */ public ViewHolder setText(int viewId,String text){ TextView tv=getView(viewId); tv.setText(text); return this; } /** * 设置图片 * @param viewId * @param resId * @return */ public ViewHolder setImageResource(int viewId,int resId){ ImageView view=getView(viewId); view.setImageResource(resId); return this; } } |
OptimizeAdapter.java
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package cn.edu.bzu.adapter; import java.util.List; import android.content.Context; import cn.edu.bzu.entity.Information; import cn.edu.bzu.util.CommonAdapter; import cn.edu.bzu.util.ViewHolder; import cn.edu.bzu.weibo_looking.R; public class OptimizeAdapter extends CommonAdapter<Information> { public OptimizeAdapter(Context context, List<Information> datas) { super(context, datas); } @Override public void convert(ViewHolder holder, Information information) { //给控件赋值，通过getter/setter方法实现 holder.setText(R.id.Name,information.getName()); holder.setText(R.id.Time, information.getDate()); holder.setText(R.id.Contents,information.getContent()); holder.setImageResource(R.id.Iv, information.getImgId()); } } |
