Android RecyclerView添加上拉加载更多效果
作者：段炼Android
这篇文章主要为大家详细介绍了Android RecyclerView添加上拉加载更多效果，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
先看一下效果
刷新的时候是这样的:
没有更多的时候是这样的:
既然有刷新的时候有两种状态就要定义两个状态
//普通布局的type static final int TYPE_ITEM = 0; //脚布局 static final int TYPE_FOOTER = 1;
在特定的时候去显示:
@Override
public int getItemViewType(int position) {
//如果position加1正好等于所有item的总和,说明是最后一个item,将它设置为脚布局
if (position + 1 == getItemCount()) {
return TYPE_FOOTER;
} else {
return TYPE_ITEM;
}
}
然后根据这个type来inflate不同的布局:
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_ITEM) {
View view = View.inflate(mContext, R.layout.item_recycler, null);
MyViewHolder holder = new MyViewHolder(view);
return holder;
} else if (viewType == TYPE_FOOTER) {
//脚布局
View view = View.inflate(mContext, R.layout.recycler_load_more_layout, null);
FootViewHolder footViewHolder = new FootViewHolder(view);
return footViewHolder;
}
return null;
}
以上只是控制了Loading布局的出现可隐藏,还要2中状态需要控制就是上面的2个图,一个是正在加载,一个是加载完成状态,这两个状态在adapter里显然是控制不了的,必须要在请求数据的时候才能知道这两种状态,而加载数据又是在activity中执行的,所以我们需要一个用来传递状态的方法:
/**
* 改变脚布局的状态的方法,在activity根据请求数据的状态来改变这个状态
*
* @param state
*/
public void changeState(int state) {
this.footer_state = state;
notifyDataSetChanged();
}
用来接收状态的变量:
//上拉加载更多 // static final int PULL_LOAD_MORE = 0; //正在加载更多 static final int LOADING_MORE = 1; //没有更多 static final int NO_MORE = 2; //脚布局当前的状态,默认为没有更多 int footer_state = 1;
然后就可以根据这几种状态来控制布局控件的改变了:
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MyViewHolder) {
((MyViewHolder) holder).mTextView.setText(mList.get(position));
} else if (holder instanceof FootViewHolder) {
FootViewHolder footViewHolder = (FootViewHolder) holder;
if (position == 0) {//如果第一个就是脚布局,,那就让他隐藏
footViewHolder.mProgressBar.setVisibility(View.GONE);
footViewHolder.tv_line1.setVisibility(View.GONE);
footViewHolder.tv_line2.setVisibility(View.GONE);
footViewHolder.tv_state.setText("");
}
switch (footer_state) {//根据状态来让脚布局发生改变
// case PULL_LOAD_MORE://上拉加载
// footViewHolder.mProgressBar.setVisibility(View.GONE);
// footViewHolder.tv_state.setText("上拉加载更多");
// break;
case LOADING_MORE:
footViewHolder.mProgressBar.setVisibility(View.VISIBLE);
footViewHolder.tv_line1.setVisibility(View.GONE);
footViewHolder.tv_line2.setVisibility(View.GONE);
footViewHolder.tv_state.setText("正在加载...");
break;
case NO_MORE:
footViewHolder.mProgressBar.setVisibility(View.GONE);
footViewHolder.tv_line1.setVisibility(View.VISIBLE);
footViewHolder.tv_line2.setVisibility(View.VISIBLE);
footViewHolder.tv_state.setText("我是有底线的");
footViewHolder.tv_state.setTextColor(Color.parseColor("#ff00ff"));
break;
}
}
}
不要忘了返回的count也要加1,因为添加了一个脚布局:
@Override
public int getItemCount() {
return mList != null ? mList.size() + 1 : 0;
}
那么什么时候去传递状态到adapter呢?这里就需要给RecyclerView添加滑动监听了,当他滑动到底部的时候显示加载中的状态:
//给recyclerView添加滑动监听
mRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
/*
到达底部了,如果不加!isLoading的话到达底部如果还一滑动的话就会一直进入这个方法
就一直去做请求网络的操作,这样的用户体验肯定不好.添加一个判断,每次滑倒底只进行一次网络请求去请求数据
当请求完成后,在把isLoading赋值为false,下次滑倒底又能进入这个方法了
*/
if (newState == RecyclerView.SCROLL_STATE_IDLE && lastVisibleItem + 1 == mAdapter.getItemCount() && !isLoading) {
//到达底部之后如果footView的状态不是正在加载的状态,就将 他切换成正在加载的状态
if (page < totlePage) {
Log.e("duanlian", "onScrollStateChanged: " + "进来了");
isLoading = true;
mAdapter.changeState(1);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
getData();
page++;
}
}, 2000);
} else {
mAdapter.changeState(2);
}
}
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
//拿到最后一个出现的item的位置
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
}
});
重点就这几个,下面给出脚布局:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ll_below"
android:layout_width="match_parent"
android:layout_height="45dp"
>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="45dp"
android:gravity="center"
android:orientation="horizontal">
<TextView
android:id="@+id/tv_line1"
android:layout_width="60dp"
android:layout_height="1dp"
android:layout_marginRight="10dp"
android:background="#ff00ff"
android:visibility="gone"/>
<ProgressBar
android:id="@+id/progressbar"
android:layout_width="25dp"
android:layout_height="25dp"
android:visibility="visible"/>
<TextView
android:id="@+id/foot_view_item_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="4dp"
android:text="上拉加载更多"/>
<TextView
android:id="@+id/tv_line2"
android:layout_width="60dp"
android:layout_height="1dp"
android:layout_marginLeft="10dp"
android:background="#ff00ff"
android:visibility="gone"/>
</LinearLayout>
</RelativeLayout>
Adapter的代码:
package com.duanlian.recyclerviewloadmoredemo;
import android.content.Context;
import android.graphics.Color;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;
import java.util.List;
public class MyRecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context mContext;
private List<String> mList;
//普通布局的type
static final int TYPE_ITEM = 0;
//脚布局
static final int TYPE_FOOTER = 1;
// //上拉加载更多
// static final int PULL_LOAD_MORE = 0;
//正在加载更多
static final int LOADING_MORE = 1;
//没有更多
static final int NO_MORE = 2;
//脚布局当前的状态,默认为没有更多
int footer_state = 1;
public MyRecyclerAdapter(Context context, List<String> list) {
mContext = context;
mList = list;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_ITEM) {
View view = View.inflate(mContext, R.layout.item_recycler, null);
MyViewHolder holder = new MyViewHolder(view);
return holder;
} else if (viewType == TYPE_FOOTER) {
//脚布局
View view = View.inflate(mContext, R.layout.recycler_load_more_layout, null);
FootViewHolder footViewHolder = new FootViewHolder(view);
return footViewHolder;
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MyViewHolder) {
((MyViewHolder) holder).mTextView.setText(mList.get(position));
} else if (holder instanceof FootViewHolder) {
FootViewHolder footViewHolder = (FootViewHolder) holder;
if (position == 0) {//如果第一个就是脚布局,,那就让他隐藏
footViewHolder.mProgressBar.setVisibility(View.GONE);
footViewHolder.tv_line1.setVisibility(View.GONE);
footViewHolder.tv_line2.setVisibility(View.GONE);
footViewHolder.tv_state.setText("");
}
switch (footer_state) {//根据状态来让脚布局发生改变
// case PULL_LOAD_MORE://上拉加载
// footViewHolder.mProgressBar.setVisibility(View.GONE);
// footViewHolder.tv_state.setText("上拉加载更多");
// break;
case LOADING_MORE:
footViewHolder.mProgressBar.setVisibility(View.VISIBLE);
footViewHolder.tv_line1.setVisibility(View.GONE);
footViewHolder.tv_line2.setVisibility(View.GONE);
footViewHolder.tv_state.setText("正在加载...");
break;
case NO_MORE:
footViewHolder.mProgressBar.setVisibility(View.GONE);
footViewHolder.tv_line1.setVisibility(View.VISIBLE);
footViewHolder.tv_line2.setVisibility(View.VISIBLE);
footViewHolder.tv_state.setText("我是有底线的");
footViewHolder.tv_state.setTextColor(Color.parseColor("#ff00ff"));
break;
}
}
}
@Override
public int getItemViewType(int position) {
//如果position加1正好等于所有item的总和,说明是最后一个item,将它设置为脚布局
if (position + 1 == getItemCount()) {
return TYPE_FOOTER;
} else {
return TYPE_ITEM;
}
}
@Override
public int getItemCount() {
return mList != null ? mList.size() + 1 : 0;
}
/**
* 正常布局的ViewHolder
*/
class MyViewHolder extends RecyclerView.ViewHolder {
TextView mTextView;
public MyViewHolder(View itemView) {
super(itemView);
mTextView = (TextView) itemView.findViewById(R.id.item_textView);
}
}
/**
* 脚布局的ViewHolder
*/
public static class FootViewHolder extends RecyclerView.ViewHolder {
private ProgressBar mProgressBar;
private TextView tv_state;
private TextView tv_line1;
private TextView tv_line2;
public FootViewHolder(View itemView) {
super(itemView);
mProgressBar = (ProgressBar) itemView.findViewById(R.id.progressbar);
tv_state = (TextView) itemView.findViewById(R.id.foot_view_item_tv);
tv_line1 = (TextView) itemView.findViewById(R.id.tv_line1);
tv_line2 = (TextView) itemView.findViewById(R.id.tv_line2);
}
}
/**
* 改变脚布局的状态的方法,在activity根据请求数据的状态来改变这个状态
*
* @param state
*/
public void changeState(int state) {
this.footer_state = state;
notifyDataSetChanged();
}
}
activity中的代码:
package com.duanlian.recyclerviewloadmoredemo;
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecycler;
private List<String> mList;
private List<String> list;
private MyRecyclerAdapter mAdapter;
LinearLayoutManager linearLayoutManager;
int lastVisibleItem;
int page = 0;
boolean isLoading = false;//用来控制进入getdata()的次数
int totlePage = 5;//模拟请求的一共的页数
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
getData();
}
private void initView() {
mRecycler = (RecyclerView) findViewById(R.id.recycler);
linearLayoutManager = new LinearLayoutManager(this);
mRecycler.setLayoutManager(linearLayoutManager);
mList = new ArrayList<>();
mAdapter = new MyRecyclerAdapter(this, mList);
mRecycler.setAdapter(mAdapter);
//给recyclerView添加滑动监听
mRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
/*
到达底部了,如果不加!isLoading的话到达底部如果还一滑动的话就会一直进入这个方法
就一直去做请求网络的操作,这样的用户体验肯定不好.添加一个判断,每次滑倒底只进行一次网络请求去请求数据
当请求完成后,在把isLoading赋值为false,下次滑倒底又能进入这个方法了
*/
if (newState == RecyclerView.SCROLL_STATE_IDLE && lastVisibleItem + 1 == mAdapter.getItemCount() && !isLoading) {
//到达底部之后如果footView的状态不是正在加载的状态,就将 他切换成正在加载的状态
if (page < totlePage) {
Log.e("duanlian", "onScrollStateChanged: " + "进来了");
isLoading = true;
mAdapter.changeState(1);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
getData();
page++;
}
}, 2000);
} else {
mAdapter.changeState(2);
}
}
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
//拿到最后一个出现的item的位置
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
}
});
}
/**
* 模拟请求数据
*/
private void getData() {
list = new ArrayList<>();
for (int i = 0; i < 10; i++) {
list.add("第" + i + "条");
}
mList.addAll(list);
isLoading = false;
mAdapter = new MyRecyclerAdapter(this, mList);
mRecycler.setAdapter(mAdapter);
}
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。