ANdroid RecyclerView的基本用法
MargheritaJ
8年前
<p>单一的RecyclerView实现的效果图:</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/d9f31ac42d74ad7e4459efcde785d415.jpg"></p> <p style="text-align:center">仿QQ动态界面.jpg</p> <p>上图随意用的几个Android自带的icon,不太美观请轻点吐槽....</p> <p>既然本篇博文介绍的是基本用法,仅提供本人拙见,就不手把手教程如何实现,所以请伸手党止步哈.</p> <p>引用</p> <ul> <li>Gradle依赖 <pre> <code class="language-java">compile 'com.android.support:recyclerview-v7:25.0.1'</code></pre> </li> <li>主布局引用 <pre> <code class="language-java"><android.support.v7.widget.RecyclerView android:id="@+id/recyclerview" android:scrollbars="none" android:layout_width="match_parent" android:layout_height="match_parent" /></code></pre> </li> </ul> <p>LayoutManager:</p> <p>这是一个抽象类,负责将每个Item视图在RecylerView中的布局,系统提供了3个实现类:</p> <ul> <li>LinearLayoutManager 现行管理器,支持横向、纵向。</li> <li>GridLayoutManager 网格布局管理器</li> <li> <p>StaggeredGridLayoutManager 瀑布就式布局管理器</p> <pre> <code class="language-java">LinearLayoutManager mLinearLayoutManager = new LinearLayoutManager(MainActivity.this); //GridLayoutManager mGridLayoutManager = new GridLayoutManager(MainActivity.this, 4); /*StaggeredGridLayoutManager mStaggeredGridLayoutManager = new StaggeredGridLayoutManager(4, StaggeredGridLayoutManager.VERTICAL);*/ mLinearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);//竖直方向 //水平方向:LinearLayoutManager.HORIZONTAL</code></pre> </li> </ul> <p>ItemAnimator:</p> <p>ItemAnimator也是一个抽象类,系统为我们提供了一种默认的实现类,当Adapter执行notifyItemRemoved()、</p> <p>notifyItemInserted()进行增加/删除某一项Item时会有动画效果,还用一种是移动Item。</p> <pre> <code class="language-java">DefaultItemAnimator mDefaultItemAnimator=new DefaultItemAnimator();</code></pre> <p>DividerItemDecoration</p> <p>顾名思义就是Item间的分割线,实现很简单(注意RecyclerView包版本)</p> <pre> <code class="language-java">DividerItemDecoration mDividerItemDecoration =new DividerItemDecoration(MainActivity.this,DividerItemDecoration.VERTICAL);</code></pre> <p>分割线样式在你的AppTheme里面添加:</p> <pre> <code class="language-java"><!-- Base application theme. --> <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar"> ... <item name="android:listDivider">@drawable/divider_bg</item> //shape </style></code></pre> <p>RecyclerViewAdapter</p> <p>Adapter 没有提供Item点击回调给我们,因此,我们需要主动回调Item或Item内控件的点击事件。</p> <pre> <code class="language-java">public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> { Context mContext; OnItemClickListener onItemClickListener; List<UserInfo> userInfoList; public RecyclerViewAdapter(Context mContext,List<UserInfo> userInfoList) { this.mContext = mContext; this.userInfoList = userInfoList; } @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view = LayoutInflater.from(mContext).inflate(R.layout.item_data_list, parent, false); return new ViewHolder(view); } @Override public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) { ViewHolder vh = (ViewHolder) holder; /*当ItemView被点击时,我们通过接口回调给调用方法。如果还需对外提供ItemView内某个Button或 TextView的点击事件,将vh.itemView改为相应控件即可*/ UserInfo userInfo = userInfoList.get(position); if(userInfo.getName()!=null) { vh.tv_name..setText(userInfo.getName()); } vh.itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if (onItemClickListener != null) { onItemClickListener.onItemClick(); } } }); } //向外提供点击回调方法。 public void setOnItemClickListener(OnItemClickListener onItemClickListener) { this.onItemClickListener = onItemClickListener; } //Item的点击接口 public interface OnItemClickListener { void onItemClick(); } @Override public int getItemCount() { //Item总数 return userInfoList !=null ? userInfoList.size() : 0; } @Override public int getItemViewType(int position) { return super.getItemViewType(position); } private class ViewHolder extends RecyclerView.ViewHolder { TextView tv_name; ViewHolder(View itemView) { super(itemView); tv_name = (TextView) itemView.findViewById(R.id.tv_name); } } }</code></pre> <p>以上是最简单的Adapter写法,粗略介绍一下每个方法的作用</p> <ul> <li> <p>getItemCount():</p> <p>视图总数,如果我们不需要多样式的Item显示不同的数据,可以像上面写的一样返回List数据的个数。如果我们需要像博文开头的效果图那样的效果,就需要我们计算好所有Item的数量,例如头布局数+中间布局数+脚布局数+分割线数。</p> </li> <li> <p>getItemViewType(int position):</p> <p>该方法里有个参数position,当Adapter正在加载位置为position的ItemView视图样式时,通过这个方法获取到我们自定义的ItemViewType,再一步步的通过这个ItemViewType加载视图样式然后填充数据...例如效果图,头部布局的位置(position)为0,我们设置头部的CardView布局的ItemViewType为0(不一定是0),在onCreateViewHolder方法中就可以通过viewType来加载相应的Item视图</p> <pre> <code class="language-java">@Override public int getItemViewType(int position) { if (position == 0){ return topViewType;//private final int topViewType = 0; } ... }</code></pre> </li> <li> <p>onCreateViewHolder(ViewGroup parent, int viewType):</p> <p>既然要实现多样式,那么你不同的Item的样式要改吧,我们可以通过viewType去加载相应的布局,并将布局传入ViewHolder进行保存,以达复用。</p> <pre> <code class="language-java">@Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { if (viewType == topViewType){ View view = LayoutInflater.from(mContext).inflate(R.layout.item_top, parent, false); return new ViewHolder(view); } ... }</code></pre> </li> <li> <p>onBindViewHolder(RecyclerView.ViewHolder holder, int position) :</p> <p>好了,拿到Adapter的position位置上的ViewHolder,我们将数据绑定在holder上。但是这里的position是Adapter的位置。也就是说,如果现在要绑定中间布局的数据,我们的position为头布局Item数+position。</p> <pre> <code class="language-java">@Override public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) { if (holder instanceof ViewHolder){ ViewHolder vh = (ViewHolder) holder; } ... }</code></pre> </li> <li> <p>调用</p> <pre> <code class="language-java">RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerview); recyclerView.setItemAnimator(mDefaultItemAnimator);//设置默认动画(可选) recyclerView.setLayoutManager(mLinearLayoutManager);//设置布局管理器(必选) recyclerView.addItemDecoration(new DividerItemDecoration(this, mDividerItemDecoration);//设置分割线(可选) RecyclerViewAdapter recyclerViewAdapter = new RecyclerViewAdapter(MainActivity.this, userInfoList); recyclerView.setAdapter(recyclerViewAdapter);//加载适配器(必选)</code></pre> </li> </ul> <p> </p> <p>来自:http://www.jianshu.com/p/d734c1f62e84</p> <p> </p>