android5.0中RecycleView的用法

浏览数：95 / 时间：2015年06月11日

最近学习了android5.0中新增的一个组件RecycleView，是用来代替当前的listview开发的，是因为在RecycleView中已经有了viewholder缓存，并且不同的item之间可以设置不同的布局。能非常有效地维护了意见数量有限，滚动大的数据集。使用 RecyclerView当你拥有的数据的集合，它的元素在运行时改变基于用户行为和网络事件的小部件

首先看看RecyclerView的一个小例子：

需要引入：android-support-v7-appcompat.jar

android-v7-RecyclerView.jar来支持低版本的android系统

新建一个my_layout.xml布局文件：里边放置一个RecyclerView

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<android.support.v7.widget.RecyclerView
android:id="@+id/rvlist"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
/>

在之前的listview开发中，我们需要自定义viewholder来缓存listView中的数据，而在RecyclerView中，已经封装好了viewholder在adapter中，接下来自定义我们的adapter

[java] view plain copy

public class MyAdapter2 extends RecyclerView.Adapter<MyAdapter2.ViewHolder>
{
// 数据集
private String[] mDataset;
public MyAdapter2(String[] dataset)
{
super();
mDataset = dataset;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i)
{
// 创建一个View，简单起见直接使用系统提供的布局，就是一个TextView
View view = View.inflate(viewGroup.getContext(),R.layout.viewholder_item, null);
// 创建一个ViewHolder
ViewHolder holder = new ViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, int i)
{
// 绑定数据到ViewHolder上
viewHolder.mTextView.setText(mDataset[i]);
}
@Override
public int getItemCount()
{
return mDataset.length;
}
public static class ViewHolder extends RecyclerView.ViewHolder
{
public TextView mTextView;
public ViewHolder(View itemView)
{
super(itemView);
// mTextView = (TextView) itemView;
mTextView = (TextView) itemView.findViewById(R.id.view_text_id);
}
}
}

在activity这样调用，并设置adapter

[java] view plain copy

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rvlist);
// 创建一个线性布局管理器
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
// 设置布局管理器
recyclerView.setLayoutManager(layoutManager);
// 创建数据集
String[] dataset = new String[100];
for (int i = 0; i < dataset.length; i++){
dataset[i] = "item" + i;
}
// 创建Adapter，并指定数据集
MyAdapter2 adapter = new MyAdapter2(dataset);
// 设置Adapter
recyclerView.setAdapter(adapter);
}

运行效果：

技术分享

在这个例子中只是用到了最基本的布局，下面结合android中新增的CardView和RecycleView实现一个复杂的布局：

先看效果图：

技术分享

CardView继承自FrameLayout，允许你在card视图中显示信息. CardView也可以设置阴影和圆角。（其实现在很多应用都自定义了Card视图，Google这回将card视图作为基本控件，可以拿来直接使用了）

Layout中为CardView设置圆角使用card_view:cardCornerRadius属性

代码中为CardView设置圆角使用CardView.setRadius方法

为CardView设置背景颜色使用card_view:cardBackgroundColor属性

1.在item布局中引入cardview组件

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<android.support.v7.widget.CardView
android:id="@+id/cardview_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:cardCornerRadius="5dp"
app:cardElevation="0dp" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp" >
<ImageView
android:id="@+id/image_id"
android:layout_width="20dp"
android:layout_height="20dp"
android:layout_alignParentLeft="true"
/>
<TextView
android:id="@+id/text_id"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:textColor="#f89ef5"
android:textSize="20dp"
android:layout_centerInParent="true" />
</RelativeLayout>
</android.support.v7.widget.CardView>

需要注意的是要在最底层的layout中引入cardview的命名空间：

xmlns:app=http://schemas.android.com/apk/res-auto

要实现不同的item有不同的布局，需要有一个type字段来作为区分，这里，我新建一个UserInfo类，如下：

[java] view plain copy

public class UserInfo {
public static final int hasImage = 1;
public static final int noImage = 2;
private String mUserName;
private int userImage;
int type;
public String getmUserName() {
return mUserName;
}
public void setmUserName(String mUserName) {
this.mUserName = mUserName;
}
public int getUserImage() {
return userImage;
}
public void setUserImage(int userImage) {
this.userImage = userImage;
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
public UserInfo(String mUserName, int type) {
this.mUserName = mUserName;
this.type = type;
}
public UserInfo(String mUserName, int userImage, int type) {
this.mUserName = mUserName;
this.userImage = userImage;
this.type = type;
}
}

hasImage和noImage分别表示该item需不需要加载图片，来加载不同的布局。

接下来看看Adapter的代码：

[java] view plain copy

public class MyAdapter extends RecyclerView.Adapter<ViewHolder>{
private List<UserInfo>mList = null;
private Context context = null;
public MyAdapter(List<UserInfo> mList, Context context) {
super();
this.mList = mList;
this.context = context;
// for (int i = 0; i < mList.size(); i++) {
// Log.d("liuhang","==="+mList.get(i).getmUserName()+"==="+mList.get(i).getUserImage());
// }
}
public void addToList(UserInfo info,int position) {
mList.add(0, info);
notifyItemInserted(position);
notifyDataSetChanged();
}
public class TextOnClick implements OnClickListener {
private int position = 0;
public TextOnClick(int position) {
this.position = position;
}
@Override
public void onClick(View v) {
Toast.makeText(context,"text the name:"+mList.get(position).getmUserName(),1000).show();
}
}
public class ImageOnclick implements OnClickListener {
private int position = 0;
public ImageOnclick(int position) {
this.position = position;
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(context,"image the imageId:"+mList.get(position).getUserImage(),1000).show();
}
}
public class ItemOnClick implements OnItemClickListener {
@Override
public void onItemClick(AdapterViewCompat<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
Toast.makeText(context,"you choose the item",1000).show();
}
}
@Override
public int getItemCount() {
return mList.size();
}
public class TextViewHolder extends RecyclerView.ViewHolder {
public TextView textView = null;
public TextViewHolder(View view) {
super(view);
this.textView = (TextView) view.findViewById(R.id.text_id);
}
}
public class ImageTextViewHolder extends RecyclerView.ViewHolder {
public ImageView imageView = null;
public TextView textView = null;
public ImageTextViewHolder(View view) {
super(view);
this.imageView = (ImageView) view.findViewById(R.id.image_id);
this.textView = (TextView) view.findViewById(R.id.text_id);
}
}
@Override
public int getItemViewType(int position) {
// TODO Auto-generated method stub
return mList.get(position).getType();
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
switch (getItemViewType(position)) {
case UserInfo.hasImage:
ImageTextViewHolder imageTextViewHolder = (ImageTextViewHolder) holder;
imageTextViewHolder.imageView.setImageResource(mList.get(position).getUserImage());
imageTextViewHolder.textView.setText(mList.get(position).getmUserName());
imageTextViewHolder.textView.setOnClickListener(new TextOnClick(position));
imageTextViewHolder.imageView.setOnClickListener(new ImageOnclick(position));
break;
case UserInfo.noImage:
TextViewHolder textViewHolder = (TextViewHolder) holder;
textViewHolder.textView.setText(mList.get(position).getmUserName());
textViewHolder.textView.setOnClickListener(new TextOnClick(position));
}
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int type) {
ViewHolder holder = null;
View view = null;
switch (type) {
case UserInfo.hasImage:
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_text_image_item,null);
holder = new ImageTextViewHolder(view);
break;
case UserInfo.noImage:
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_text_item,null);
holder = new TextViewHolder(view);
break;
}
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return holder;
}
}