封裝好的萬能ViewHolder和Adapter

下面我把自己優化的萬能ViewHolder和Adapter跟大家分享一下，也為自己留一個記錄。話不多說，直接上代碼：

Viewholder：

package com.example.xf.test.adapter;

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

public class ViewHolder {
    private View convertView;
    private int position;
    //SparseArray是一個map，但是它比map效率更高，實作了integer與View的鍵值關系
    private SparseArray<View> mArray;

    private ViewHolder(Context context, View convertView, ViewGroup parent, int position, int layoutId) {
        this.convertView = convertView;
        this.position = position;

        this.convertView = LayoutInflater.from(context).inflate(layoutId, parent, false);
        this.convertView.setTag(this);
        mArray = new SparseArray<View>();
    }
    //在adapter中使用這個方法去建立ViewHolder，需要先判斷convertView是否為空
    public static ViewHolder get(Context context, View convertView, ViewGroup parent, int position, int layoutId) {
        if (convertView == null) {
            return new ViewHolder(context, convertView, parent, position, layoutId);
        } else {
            ViewHolder holder = (ViewHolder) convertView.getTag();
            holder.position = position;
            return holder;
        }
    }
    //取得item布局中的id為viewId的控件
    public <T extends View> T getView(int viewId) {

        View view = mArray.get(viewId);
        if (view == null) {
            view = convertView.findViewById(viewId);
            mArray.put(viewId, view);
        }
        return (T) view;
    }

    public View getConvertView() {
        return convertView;
    }
    //為TextView設定文本
    public ViewHolder setText(int viewId,String text){
        TextView view = getView(viewId);
        view.setText(text);
        return this;
    }
}
           

CommonAdapter（注意這個類是abstract）：

package com.example.xf.test.adapter;

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

import java.util.List;

/**
 * Created by xf on 2015/4/18.
 */
public abstract class CommonAdapter<T> extends BaseAdapter {
    private Context context;
    private List<T> list;
    private int layoutId;

    public CommonAdapter(Context context, List<T> list, int layoutId) {
        this.context = context;
        this.list = list;
        this.layoutId = layoutId;
    }

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

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = ViewHolder.get(context, convertView, parent, position, layoutId);
        convert(holder, list.get(position));
        return holder.getConvertView();
    }

    //将此方法開放出去，在adapter中實作
    public abstract void convert(ViewHolder holder, T t);
}
           

實際項目中需要使用的Adapter是繼承這個CommonAdapter的：

package com.example.xf.test.adapter;

import android.content.Context;

import com.example.xf.test.R;
import com.example.xf.test.pojo.Bean;

import java.util.List;

/**
 * Created by xf on 2015/4/19.
 */
public class CommonAdapterImpl extends CommonAdapter<Bean> {
    public CommonAdapterImpl(Context context, List<Bean> list, int layoutId) {
        super(context, list, layoutId);
    }

    @Override
    public void convert(ViewHolder holder, Bean bean) {
        holder.setText(R.id.id_textview1, bean.getDestription()).setText(R.id.id_textview2, bean.getName());
    }
}
           

也就是說每個ListView隻需要寫這麼幾行的代碼就能解決戰鬥，是不是很爽！

【注】：1.制作這個ViewHolder的關鍵就是将Adapter的getView中的convertView封裝進ViewHolder中。

       2.了解泛型，在我自己了解泛型就是可以讓你在建構代碼的時候不指定類型，使用的時候在指定。

Demo位址：http://download.csdn.net/detail/xf396191344/9264617