Android之Adapter的封装与抽象

在开发的过程中，常常会用到ViewPager、ListView、GridView等、这些带有Item的视图控件，而这些控件有个共同点就是都要用到它们的适配器，我们在实现视图展示时，一般都会去写个自定义的适配器去继承PagerAdapter或Adapter或Adapter的子类，因为Android源码自带的这些适配器都比较抽象，往往在我们开发时，写的一些自定义适配器都需要重写Adapter父类的一些方法，在重写时，有很多较通用性的代码，比较耦合，下面将PagerAdapter和Adapter的子类BaseAdapter进行了封装与抽象，免去了每次都去重写这些通用的代码，代码如下：

1.ViewPagerAdapter 

/**
 * 通用ViewPagerAdapter
 * @author Jenly
 *
 */
public class ViewPagerAdapter extends PagerAdapter {

	private List<View> listViews = null;

	public ViewPagerAdapter(List<View> listViews) {
		this.listViews = listViews;
	}
	
	@Override
	public void destroyItem(View container, int position, Object object) {
		((ViewPager)container).removeView(listViews.get(position));
	}
	
	@Override
	public int getCount() {
		return listViews.size();
	}
	
	@Override
	public Object instantiateItem(View container, int position) {
		((ViewPager)container).addView(listViews.get(position),0);
		return listViews.get(position);
	}

	@Override
	public boolean isViewFromObject(View paramView, Object paramObject) {
		return paramView == paramObject;
	}

	public List<View> getListViews() {
		return listViews;
	}

	public void setListViews(List<View> listViews) {
		this.listViews = listViews;
	}
	
	
}

2.AbstractAdapter

/**
 * 抽象适配器（免去一些有共性的代码）
 * @author Jenly
 *
 * @param <T>
 */
public abstract class AbstractAdapter<T> extends BaseAdapter {
	
	protected Context context;
	
	protected List<T> listData;
	
	protected LayoutInflater layoutInflater;
	
	public AbstractAdapter(Context context,List<T> listData){
		this.context = context;
		this.listData = listData;
		layoutInflater = LayoutInflater.from(context);
	}

	@Override
	public int getCount() {
		if(listData!=null){
			return listData.size();
		}
		return 0;
	}

	@Override
	public Object getItem(int position) {
		if(listData!=null){
			return listData.get(position);
		}
		return null;
	}

	@Override
	public long getItemId(int position) {
		return position;
	}
	
	public List<T> getListData() {
		return listData;
	}

	public void setListData(List<T> listData) {
		this.listData = listData;
	}
	

}

3.HolderAdapter

/**
 * 通用适配器（适合一些常规的适配器）
 * @author Jenly
 *
 * @param <T>
 */
public abstract class HolderAdapter<T> extends AbstractAdapter<T>{

	public HolderAdapter(Context context, List<T> listData) {
		super(context, listData);
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		Object holder = null;
		if(convertView==null){
			convertView = buildConvertView(layoutInflater);
			holder = buildHolder(convertView);
			
			convertView.setTag(holder);
		}else{
			holder = convertView.getTag();
		}
		bindViewData(holder,listData.get(position),position);
		
		return convertView;
	}
	
	/**
	 * 建立convertView
	 * @param layoutInflater
	 * @return
	 */
	public abstract View buildConvertView(LayoutInflater layoutInflater);
	
	/**
	 * 建立视图Holder
	 * @param convertView
	 * @return
	 */
	public abstract Object buildHolder(View convertView);
	
	/**
	 * 绑定数据
	 * @param holder
	 * @param t
	 * @param position
	 */
	public abstract void bindViewDatas(Object holder,T t,int position);
	

}

下面是个自定义的测试适配器，继承HolderAdapter实现它的三个抽象方法：

public class TestHolderAdapter extends HolderAdapter<String>{

	public TestHolderAdapter(Context context, List<String> listData) {
		super(context, listData);
	}

	@Override
	public View buildConvertView(LayoutInflater layoutInflater) {
		return layoutInflater.inflate(R.layout.activity_list_item, null);
	}

	@Override
	public Object buildHolder(View convertView) {
		ViewHolder holder = new ViewHolder();
		holder.tv = (TextView)convertView.findViewById(R.id.tv);
		return holder;
	}

	@Override
	public void bindViewDatas(Object holder, String t, int position) {
		((ViewHolder)holder).tv.setText(t);
	}
	
	private static class ViewHolder{
		TextView tv;
	}

}