转载：https://www.cnblogs.com/it-tsz/p/11372187.html
在Android开发中，RecyclerView算是使用频率非常广泛的组件了吧，在这里对RecyclerView比较常用的下拉刷新和上拉加载更多的功能实现做个记录，方便以后查看。
在这里下拉刷新使用的是官方提供的SwipeRefreshLayout，然后上拉加载更多的功能使用的是第三方库BaseRecyclerViewAdapterHelper实现。
依赖导入
在项目build.gradle文件中添加以下代码导入依赖：
implementation 'com.github.CymChad:BaseRecyclerViewAdapterHelper:2.9.46' implementation group: 'androidx.recyclerview', name: 'recyclerview', version: '1.1.0-alpha01'
下拉刷新和上拉加载更多实现
实体类UserData
public class UserData {
private String userName;
publicUserData(){
}
publicUserData(String userName){
this.userName = userName;
}
publicStringgetUserName(){
return userName;
}
publicvoidsetUserName(String userName){
this.userName = userName;
}
}
RecyclerView对应的Adapter
import android.graphics.Color;
import com.chad.library.adapter.base.BaseQuickAdapter;
import com.chad.library.adapter.base.BaseViewHolder;
import java.util.List;
import androidx.annotation.Nullable;
public class MainAdapter extends BaseQuickAdapter<UserData, BaseViewHolder> {
public MainAdapter(int layoutResId, @Nullable List<UserData> data) {
super(layoutResId, data);
}
@Override
protected void convert(BaseViewHolder helper, UserData item) {
int adapterPosition = helper.getAdapterPosition();
if (adapterPosition % 2 == 0) {
helper.setBackgroundColor(R.id.rlContent, Color.RED);
}else {
helper.setBackgroundColor(R.id.rlContent, Color.YELLOW);
}
helper.setText(R.id.tvName, item.getUserName());
}
}
RecyclerView对应的Adapter布局文件recycler_item_demo.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/rlContent"
android:orientation="vertical">
<TextView
android:id="@+id/tvName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:padding="20dp"
android:text="测试"
android:textColor="#333333"
android:textSize="30dp" />
</RelativeLayout>
MainActivity
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.util.Log;
import android.view.View;
import com.chad.library.adapter.base.BaseQuickAdapter;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {
private SwipeRefreshLayout swipeRefreshLayout;
private RecyclerView recyclerView;
private List<UserData> userDatas = new ArrayList<>();
private int count = 0;
private int loadMoreCount = 0;
private MainAdapter mainAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
swipeRefreshLayout = findViewById(R.id.swipeRefreshLayout);
recyclerView = findViewById(R.id.recyclerView);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
mainAdapter = new MainAdapter(R.layout.recycler_item_demo, userDatas);
mainAdapter.setLoadMoreView(new CustomLoadMoreView());
//设置RecyclerView条目点击事件
mainAdapter.setOnItemClickListener(new BaseQuickAdapter.OnItemClickListener() {
@Override
public void onItemClick(BaseQuickAdapter adapter, View view, int position) {
UserData item = mainAdapter.getItem(position);
Log.e(MainActivity.this.getClass().getSimpleName(), "点击条目: " + position + "----userName: " + item.getUserName());
}
});
mainAdapter.setOnLoadMoreListener(new BaseQuickAdapter.RequestLoadMoreListener() {
@Override
public void onLoadMoreRequested() {
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
List<UserData> userDataList = getDatas(false);
if (loadMoreCount == 1) {
//正常加载更多，还有下一页
mainAdapter.addData(userDataList);
mainAdapter.loadMoreComplete();
} else if (loadMoreCount == 2) {
//返回加载失败
mainAdapter.loadMoreFail();
} else if (loadMoreCount == 3) {
//加载到最后
mainAdapter.addData(userDataList.subList(0, 6));
mainAdapter.loadMoreEnd();
}
}
}, 3000);
}
}, recyclerView);
recyclerView.setAdapter(mainAdapter);
swipeRefreshLayout.setOnRefreshListener(this);
onRefresh();
}
private List<UserData> getDatas(boolean isRefresh) {
if (isRefresh) {
count = 0;
}
List<UserData> dataList = new ArrayList<>();
for (int i = count; i < count + 10; i++) {
if (isRefresh) {
loadMoreCount = 0;
dataList.add(new UserData("下拉刷新数据" + i));
} else {
dataList.add(new UserData("上拉加载更多数据" + i));
}
}
if (!isRefresh) {
loadMoreCount++;
}
count += 10;
return dataList;
}
@Override
public void onRefresh() {
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
List<UserData> userDataList = getDatas(true);
mainAdapter.setNewData(userDataList);
mainAdapter.loadMoreComplete();
swipeRefreshLayout.setRefreshing(false);
}
}, 3000);
}
}
以上代码中RecyclerView的数据集使用假数据测试，并且模拟第一次上拉加载更多成功，第二次上拉加载失败，点击失败重试，最后加载完毕（即没有更多数据）
MainActivity的布局文件activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
tools:context=".MainActivity">
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
android:id="@+id/swipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
运行结果截图
图1
注意事项
加载更多的View布局是可以自定义的，自定义调用的方法：
mainAdapter.setLoadMoreView(new CustomLoadMoreView());
CustomLoadMoreView
import com.chad.library.adapter.base.loadmore.LoadMoreView;
public final class CustomLoadMoreView extends LoadMoreView {
@Override
public int getLayoutId() {
return R.layout.view_load_more;
}
@Override
protected int getLoadingViewId() {
return R.id.load_more_loading_view;
}
@Override
protected int getLoadFailViewId() {
return R.id.load_more_load_fail_view;
}
@Override
protected int getLoadEndViewId() {
return R.id.load_more_load_end_view;
}
}
加载更多布局文件view_load_more.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="@dimen/dp_40">
<LinearLayout
android:id="@+id/load_more_loading_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:visibility="visible"
android:orientation="horizontal">
<ProgressBar
android:id="@+id/pb_footer"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp" />
<TextView
android:id="@+id/tv_footer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="正在加载中..." />
</LinearLayout>
<FrameLayout
android:id="@+id/load_more_load_fail_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="gone">
<TextView
android:id="@+id/tv_prompt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="@string/brvah_load_failed"/>
</FrameLayout>
<FrameLayout
android:id="@+id/load_more_load_end_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="gone">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="@string/brvah_load_end"
android:textColor="@android:color/darker_gray"/>
</FrameLayout>
</FrameLayout>
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