Listview的适配器封装

ListView的适配器相信大家都写过太多遍了，继承BaseAdapter抽象类，重写getCount，getItem，getItemId，getView方法。为了让汽配器提高效率还要

使用ViewHolder存储convertView中的控件。其大多代码都是重复的，只有一小部分代码是不一样的。因此我么可以封装一下，就不用在写那些冗余的代码了！

自定义的ViewHolder：

package com.example.getmynumber.adapter;

import android.content.Context;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class ViewHolder {
//承载ItemView中各个控件的容器,类似于Map，不过其键值只能是Integer类型
private SparseArray<View> mViews;
private View convertView;

public ViewHolder(Context context, int position, ViewGroup parent, int itemLayoutId) {
mViews = new SparseArray<View>();
// 为viewHolder绑定到convertView
convertView = LayoutInflater.from(context).inflate(itemLayoutId, parent, false);
convertView.setTag(this);
}

/**
* 拿到一个ViewHolder对象
*
* @param context
* @param convertView
* @param parent
* @param itemLayoutId
* @param position
* @return
*/
public static ViewHolder getViewHolder(Context context, int position, View convertView,
ViewGroup parent, int itemLayoutId) {
if (convertView == null) {
return new ViewHolder(context, position, parent, itemLayoutId);
} else {
return (ViewHolder) convertView.getTag();
}
}

/**
* 根据控件id获得控件
* 方法泛型
* @param viewId
* @return
*/
public <T extends View> T getView(int viewId) {
View view = mViews.get(viewId);
if (view == null) {
view = convertView.findViewById(viewId);
mViews.put(viewId, view);
}
return (T) view;
}

/**
* 获得convertView;
* @return
*/
public View getConvertView() {
return convertView;
}

}

自定义BaseListAdapter：

package com.example.getmynumber.adapter;

import java.util.ArrayList;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

public abstract class BaseListAdapter<T> extends BaseAdapter {

private Context context;
private LayoutInflater mInflater;
private ArrayList<T> mValues;
private int itemLayoutId;

public BaseListAdapter(Context context, ArrayList<T> mValues, int itemLayoutId) {

this.context = context;
// item布局id
this.itemLayoutId = itemLayoutId;
if (mValues == null) {
this.mValues = new ArrayList<T>();
} else {
this.mValues = mValues;
}
mInflater = LayoutInflater.from(context);
}

@Override
public int getCount() {
return mValues.size();
}

@Override
public Object getItem(int position) {
return mValues.get(position);
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder helper = ViewHolder.getViewHolder(context, position, convertView, parent,
itemLayoutId);
convert(helper, mValues.get(position));
return helper.getConvertView();
}

// 需要重写的唯一方法
public abstract void convert(ViewHolder helper, T item);

}

使用方法：

myAdapter=new BaseListAdapter<String>(CustomListViewActivity.this, citys, R.layout.ll_item) {

@Override
public void convert(ViewHolder helper, String item) {
TextView tv_item=helper.getView(R.id.tv_item);
tv_item.setText(item);
}
};

只要重写一个方法是不是简单多了！