安卓日记——RecyclerView进阶（下拉上拉刷新和万能Ad
2016-06-27 本文已影响2382人
饥渴计科极客杰铿
在日常开发中简单地摆放已有数据基本不太可能，往往是要从数据库或者网络中获取然后添加到UI，这时下拉和上拉刷新肯定是家常便饭了，不用恐惧，其实这个也是非常简单的
下拉刷新其实就是用到之前我有提到的SwipeRefreshLayout，至于上拉刷新就是在RecyclerView底部加一个item，不同item一般都是要不同的viewholder的
还有那个万能的Adapter主要是采用了泛型，可以传入任何数据类型
然后ViewHolder封装了绑定控件的方法，使用起来也是非常简单
现在开讲吧
1.导入design包
compile 'com.android.support:design:23.4.0'
2.写主布局
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="@+id/srLayout"
tools:context="com.jkgeekjack.usemorerecyclerview.MainActivity">
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/recyclerView">
</android.support.v7.widget.RecyclerView>
</android.support.v4.widget.SwipeRefreshLayout>
3.写每一个item的布局
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="@dimen/activity_vertical_margin">
<ImageView
android:layout_width="50dip"
android:layout_height="50dip"
android:src="@drawable/logo"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Name"
android:textSize="35dip"
android:id="@+id/tvName"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Age"
android:textSize="20dip"
android:id="@+id/tvAge"/>
</LinearLayout>
4.写底部item的布局
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tvState"
android:text="Loading..."
android:padding="10dp"
android:gravity="center"/>
</LinearLayout>
5.写ViewHolder
其实这个ViewHolder功能并不复杂，根据id获取控件，和摆放数据的具体实现
public class ViewHolder extends RecyclerView.ViewHolder {
// SparseArray类似HaspMap不过比HashMap节省空间，方法都差不多，id和控件对应
private SparseArray<View> mViews;
private View mConvertView;
public ViewHolder( View itemView)
{
super(itemView);
mViews = new SparseArray<View>();
mConvertView=itemView;
}
//根据id和内容进行摆放
public void setText(int viewId,String msg){
TextView textView=getView(viewId);
textView.setText(msg);
}
/**
* 通过viewId获取控件
*
* @param viewId
* @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;
}
}
自己还可以增添例如setBitmap或者设置监听之类的方法
public void setBitmap(int viewId, Bitmap bitmap){
ImageView imageView=getView(viewId);
imageView.setImageBitmap(bitmap);
}
public void setOnclickListener(int viewId, View.OnClickListener onClickListener){
View view=getView(viewId);
view.setOnClickListener(onClickListener);
}
6.写万能的Adapter
虽说是万能也比较简单，有一些特殊点的内容要在用到的时候在具体写，我这里用了抽象的方法
public abstract class CommonAdapter<T> extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int TYPE_ITEM = 0;
private static final int TYPE_FOOTER = 1;
protected Context mContext;
protected int mLayoutId;
protected List<T> mDatas;
protected LayoutInflater mInflater;
public CommonAdapter(Context context, int layoutId, List<T> datas) {
mContext = context;
mInflater = LayoutInflater.from(context);
mLayoutId = layoutId;
mDatas = datas;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
if (viewType == TYPE_FOOTER) {
View view = mInflater.inflate(R.layout.item_footer, parent, false);
return new FooterViewHolder(view);
} else {
View view = mInflater.inflate(mLayoutId, parent, false);
return new ViewHolder(view);
}
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (position < mDatas.size()) {
convert((ViewHolder) holder, mDatas.get(position));
}
}
// 摆放数据只能在用的时候才写
public abstract void convert(ViewHolder holder, T t);
@Override
public int getItemCount() {
return mDatas.size() + 1;
}
//是底部iewType为TYPE_FOOTER，不是底部viewType为TYPE_ITEM
@Override
public int getItemViewType(int position) {
if (position == getItemCount()-1) {
return TYPE_FOOTER;
} else {
return TYPE_ITEM;
}
}
// 底部的ViewHolder
class FooterViewHolder extends RecyclerView.ViewHolder {
public FooterViewHolder(View itemView) {
super(itemView);
}
}
}
7.写逻辑代码
逻辑代码并不难，之前我的几篇博客都有提到相关的用法。
不懂RecyclerVIew怎么用的，请戳
安卓日记——玩转Material Design（RecyclerView+CardView篇）
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private SwipeRefreshLayout swipeRefreshLayout;
private List<UserBean> data = new ArrayList<UserBean>();
private int lastItemPosition;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//生成数据
initVar();
initView();
}
private void initView() {
//这个Adapter传进去的UserBean的List
//因为是万能的Adapter，所以摆放数据只能在用的时候才写
final CommonAdapter<UserBean> adapter = new CommonAdapter<UserBean>(this, R.layout.item_user, data) {
@Override
public void convert(ViewHolder holder, UserBean userBean) {
holder.setText(R.id.tvName, userBean.getName());
holder.setText(R.id.tvAge, userBean.getAge() + "");
}
};
swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.srLayout);
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
new Thread(new Runnable() {
@Override
public void run() {
//添加数据
initVar();
try {
// 模拟加载耗时
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 子线程中改变UI要runOnUiThread
runOnUiThread(new Runnable() {
@Override
public void run() {
// 使加载圆环消失
swipeRefreshLayout.setRefreshing(false);
//告知Adapter更新数据
adapter.notifyDataSetChanged();
Toast.makeText(MainActivity.this, "加载完成", Toast.LENGTH_SHORT).show();
}
});
}
}).start();
}
});
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
final LinearLayoutManager manager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(manager);
recyclerView.setAdapter(adapter);
recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
//recyclerView停下来而且可见的item的position是最后一个
if (newState == RecyclerView.SCROLL_STATE_IDLE && lastItemPosition + 1 == adapter.getItemCount()) {
new Thread(new Runnable() {
@Override
public void run() {
initVar();
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
runOnUiThread(new Runnable() {
@Override
public void run() {
adapter.notifyDataSetChanged();
Toast.makeText(MainActivity.this, "加载完成", Toast.LENGTH_SHORT).show();
}
});
}
}).start();
}
}
//滚动时获取最后一个可见item的position
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
lastItemPosition = manager.findLastVisibleItemPosition();
}
});
}
private void initVar() {
for (int i = 0; i < 10; i++) {
data.add(new UserBean("jack" + i, i));
}
}
}
