android开发在adapter中使用反射添加元素

android开发中最常用的控件之一就是listview,伴随listview还要有adapter和放入适配器的item.然后假设其中有一部分item的生成符合一定规律,Item item = new Item(jsonObject);那么就该考虑下用反射来生成这些元素了.

首先是item的代码

public class TestItem {
	public int id;
	public String image;
 
	public TestItem(JSONObject json) {
		try {
			id = json.getInt("id");
		} catch (JSONException e1) {
			e1.printStackTrace();
		}
		try {
			image = json.getString("image");
		} catch (JSONException e) {
			e.printStackTrace();
		}
	}
 
}

然后是生成一个item对象的代码

Object object = TestItem.class.getConstructors()[0].newInstance(json);

放入adapter之后就是

/**
 * 适配器的抽象类
 *
 * @author oldfeel
 */
public abstract class BaseBaseAdapter extends BaseAdapter {
	private List<Object> list = new LinkedList<Object>();
	/** 适配器中元素的类 */
	private Class<?> classItem;
 
	/**
	 *
	 * @param context
	 * @param classItem
	 *            适配器中元素的类
	 */
	public BaseBaseAdapter(Class<?> classItem) {
		this.classItem = classItem;
	}
 
	/**
	 * 预处理清除列表数据和获取jsonarray
	 *
	 * @param page
	 *            页码
	 * @param json
	 *            json对象
	 * @throws JSONException
	 */
	public void putJSON(JSONObject json, int page) {
		if (page == 1) {
			list.clear();
		}
		try {
			JSONArray array = json.getJSONArray("adimage");
			for (int i = 0; i < array.length(); i++) {
				try {
					Object object = classItem.getConstructors()[0]
							.newInstance(array.getJSONObject(i));
					addItem(object);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		} catch (JSONException e1) {
			e1.printStackTrace();
		}
	}
 
	/**
	 * 清除list
	 */
	public void clear() {
		list.clear();
		notifyDataSetChanged();
	}
 
	/**
	 * 添加元素
	 *
	 * @param object
	 */
	public void addItem(Object object) {
		list.add(object);
		notifyDataSetChanged();
	}
 
	@Override
	public int getCount() {
		return list.size();
	}
 
	@Override
	public Object getItem(int position) {
		if (position > list.size() - 1) {
			return null;
		}
		return list.get(position);
	}
 
	@Override
	public long getItemId(int position) {
		return position;
	}
 
	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		return getExView(position, convertView, parent);
	}
 
	public abstract View getExView(int position, View convertView,
			ViewGroup parent);
 
}

在使用adapter的时候继承BaseBaseAdapter并输入item的类和布局文件就可以了

例如

BaseBaseAdapter adapter = new BaseBaseAdapter(
		TestItem.class) {
 
	@Override
	public View getExView(int position, View convertView,
			ViewGroup parent) {
		TestItem item = (TestItem) getItem(position);
		TextView textView = new TextView(MainActivity.this);
		textView.setText(item.image);
		return textView;
	}
};