ListView的优化使用-抽取ViewHolder以及adapter类

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我们先做一些事先的准备代码：

1.首先是就是listview的item布局：listview_item.xml代码：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:padding="10dp"    android:layout_height="match_parent">    <TextView        android:id="@+id/tetle"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:saveEnabled="true"        android:text="android标题"        android:textSize="16sp" />    <TextView        android:id="@+id/content"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@+id/tetle"        android:layout_marginTop="5dp"        android:saveEnabled="true"        android:text="android测试内容显示"        android:textSize="16sp" />    <TextView        android:id="@+id/time"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@+id/content"        android:layout_marginTop="5dp"        android:saveEnabled="true"        android:text="2016-12-30"        android:textSize="16sp" />    <TextView        android:id="@+id/phone"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentRight="true"        android:layout_below="@+id/content"        android:drawableLeft="@mipmap/ic_launcher"        android:drawablePadding="5dp"        android:gravity="center"        android:text="18720824645" /></RelativeLayout>

2.一个bean文件：

/** * Created by Administrator on 2016/12/30. * * @author diaobao-刘平 */public class Bean {    private String title;    private String content;    private String time;    private String phone;    public Bean() {    }    public Bean(String title, String content, String time, String phone) {        this.title = title;        this.content = content;        this.time = time;        this.phone = phone;    }    public String getTitle() {        return title;    }    public void setTitle(String title) {        this.title = title;    }    public String getContent() {        return content;    }    public void setContent(String content) {        this.content = content;    }    public String getTime() {        return time;    }    public void setTime(String time) {        this.time = time;    }    public String getPhone() {        return phone;    }    public void setPhone(String phone) {        this.phone = phone;    }}

好了好了这里的listview呢！就自己写了啊前期工作那就先这些吧我们进入正题

一、我们先来看看我们通常adapter适配器的使用方法，目的就是做个对比

/** * Created by Administrator on 2016/12/30. * 传统listview的适配器的使用 * @author diaobao-刘平 */public class MyAdapter extends BaseAdapter {    private List<Bean> datas = new ArrayList<>();    private LayoutInflater mLayoutInflater;    public MyAdapter(Context context, List<Bean> datas) {        this.datas = datas;        mLayoutInflater = LayoutInflater.from(context);    }    @Override    public int getCount() {        return datas.size();    }    @Override    public Object getItem(int i) {        return datas.get(i);    }    @Override    public long getItemId(int i) {        return i;    }    @Override    public View getView(int i, View contextView, ViewGroup viewGroup) {        Bean bean = (Bean) getItem(i);        ViewHolder holder = null;        if (contextView == null) {            contextView = mLayoutInflater.inflate(R.layout.listview_item, viewGroup, false);            holder = new ViewHolder(contextView);            contextView.setTag(holder);        } else {            holder = (ViewHolder) contextView.getTag();        }        holder.tetle.setText(bean.getTitle());        holder.time.setText(bean.getTime());        holder.content.setText(bean.getContent());        holder.phone.setText(bean.getPhone());        return contextView;    }    private class ViewHolder {        TextView tetle;        TextView content;        TextView time;        TextView phone;        public ViewHolder(View contextView) {            tetle = (TextView) contextView.findViewById(R.id.tetle);            time = (TextView) contextView.findViewById(R.id.time);            content = (TextView) contextView.findViewById(R.id.content);            phone = (TextView) contextView.findViewById(R.id.phone);        }    }}

二、然而我们现在呢来抽取一些我们常用的方法

1.首先呢我们就来抽取一下VivewHolder的类:

/** * Created by Administrator on 2016/12/30. * 在使用adapter时使用的viewholder方法的抽取类-公共类 * * @author diaobao-刘平 */public class ViewHolder {    private SparseArray<View> mVIews;    private View mConvertView;    private int mPosition;    /**     * 初始化ViewHolder内容     *     * @param context  上下文对象     * @param parent   ViewGroup的对象-在baseadapter中的getView（）中传入     * @param layoutId layout的id-就是listview的item     * @param ponstion ponstion的对象-在baseadapter中的getView（）中传入     */    public ViewHolder(Context context, ViewGroup parent, int layoutId, int ponstion) {        this.mPosition = ponstion;        this.mVIews = new SparseArray<View>();        mConvertView = LayoutInflater.from(context).inflate(layoutId, parent, false);        mConvertView.setTag(this);    }    /**     * @param context     上下文对象     * @param convertView view对象     * @param parent      ViewGroup的对象-在baseadapter中的getView（）中传入     * @param layoutId    layout的id-就是listview的item     * @param position    ponstion的对象-在baseadapter中的getView（）中传入     * @return     */    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;        }    }    /**     * 根据view的id获取控件     *     * @param viewId view的id     * @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;    }    /**     * 我们来偷偷懒 设置常用textview的设置值  这里还可以设置自己想设置的哦     * @param viewId textivew的id     * @param text   要设置的值内容     * @return     */    public ViewHolder SetText(int viewId, String text) {        TextView tv = getVIew(viewId);        tv.setText(text);        return this;    }}

2、为了再方便点我们把适配器也抽取了吧：命名一个commonAdapter类

/** * Created by Administrator on 2016/12/30. *提取出来的adapter的公共类 * @author diaobao-刘平 */public abstract class CommonAdapter<T> extends BaseAdapter {    protected List<T> mDatas;    protected Context mContext;    protected LayoutInflater mInflater;    public CommonAdapter(Context context, List<T> mDatas) {        this.mContext = context;        this.mDatas = mDatas;        this.mInflater = LayoutInflater.from(context);    }    @Override    public int getCount() {        return mDatas.size();    }    @Override    public Object getItem(int i) {        return mDatas.get(i);    }    @Override    public long getItemId(int i) {        return i;    }    //在这里应为getVIew方法是不一样的所以我们得把它公共出去 在这里呢你要是再懒点还可以抽取的哦  自己看着办啊      @Override    public abstract View getView(int i, View view, ViewGroup viewGroup);

3、一系列抽取之后我们在来比比看我们现在的适配器吧：第一个MyVivwHolderAdapter类

** * Created by Administrator on 2016/12/30. * 使用ViewHolder的适配器的使用 * * @author diaobao-刘平 */public class MyViewHolderAdapter extends CommonAdapter<Bean> {    public MyViewHolderAdapter(Context context, List<Bean> datas) {        super(context,datas);    }    @Override    public View getView(int i, View contextView, ViewGroup viewGroup) {        Bean bean = (Bean) getItem(i);        ViewHolder holder = ViewHolder.Get(mContext, contextView, viewGroup, R.layout.listview_item, i);        holder.SetText(R.id.tetle,bean.getTitle());        holder.SetText(R.id.time,bean.getTime());        holder.SetText(R.id.phone,bean.getPhone());        holder.SetText(R.id.content,bean.getContent());        return holder.getConvertView();    }}

是不是简单好多了呀最后结果呢我就不截图了哦你们自己运行看看吧下面给出代码哦

源码下载：源码在这哦

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