在Android項(xiàng)目中使用RecyclerView實(shí)現(xiàn)一個(gè)上拉加載更多功能？很多新手對(duì)此不是很清楚，為了幫助大家解決這個(gè)難題，下面小編將為大家詳細(xì)講解，有這方面需求的人可以來(lái)學(xué)習(xí)下，希望你能有所收獲。
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既然有刷新的時(shí)候有兩種狀態(tài)就要定義兩個(gè)狀態(tài)
//普通布局的type static final int TYPE_ITEM = 0; //腳布局 static final int TYPE_FOOTER = 1;
在特定的時(shí)候去顯示:
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重慶分公司
@Override
public int getItemViewType(int position) {
//如果position加1正好等于所有item的總和,說(shuō)明是最后一個(gè)item,將它設(shè)置為腳布局
if (position + 1 == getItemCount()) {
return TYPE_FOOTER;
} else {
return TYPE_ITEM;
}
}然后根據(jù)這個(gè)type來(lái)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) {
//腳布局
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布局的出現(xiàn)可隱藏,還要2中狀態(tài)需要控制就是上面的2個(gè)圖,一個(gè)是正在加載,一個(gè)是加載完成狀態(tài),這兩個(gè)狀態(tài)在adapter里顯然是控制不了的,必須要在請(qǐng)求數(shù)據(jù)的時(shí)候才能知道這兩種狀態(tài),而加載數(shù)據(jù)又是在activity中執(zhí)行的,所以我們需要一個(gè)用來(lái)傳遞狀態(tài)的方法:
/**
* 改變腳布局的狀態(tài)的方法,在activity根據(jù)請(qǐng)求數(shù)據(jù)的狀態(tài)來(lái)改變這個(gè)狀態(tài)
*
* @param state
*/
public void changeState(int state) {
this.footer_state = state;
notifyDataSetChanged();
}用來(lái)接收狀態(tài)的變量:
//上拉加載更多 // static final int PULL_LOAD_MORE = 0; //正在加載更多 static final int LOADING_MORE = 1; //沒(méi)有更多 static final int NO_MORE = 2; //腳布局當(dāng)前的狀態(tài),默認(rèn)為沒(méi)有更多 int footer_state = 1;
然后就可以根據(jù)這幾種狀態(tài)來(lái)控制布局控件的改變了:
@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) {//如果第一個(gè)就是腳布局,,那就讓他隱藏
footViewHolder.mProgressBar.setVisibility(View.GONE);
footViewHolder.tv_line1.setVisibility(View.GONE);
footViewHolder.tv_line2.setVisibility(View.GONE);
footViewHolder.tv_state.setText("");
}
switch (footer_state) {//根據(jù)狀態(tài)來(lái)讓腳布局發(fā)生改變
// case PULL_LOAD_MORE://上拉加載
// footViewHolder.mProgressBar.setVisibility(View.GONE);
// footViewHolder.tv_state.setText("上拉加載更多");
// 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("正在加載...");
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("我是有底線的");
footViewHolder.tv_state.setTextColor(Color.parseColor("#ff00ff"));
break;
}
}
}不要忘了返回的count也要加1,因?yàn)樘砑恿艘粋€(gè)腳布局:
@Override
public int getItemCount() {
return mList != null ? mList.size() + 1 : 0;
}那么什么時(shí)候去傳遞狀態(tài)到adapter呢?這里就需要給RecyclerView添加滑動(dòng)監(jiān)聽了,當(dāng)他滑動(dòng)到底部的時(shí)候顯示加載中的狀態(tài):
//給recyclerView添加滑動(dòng)監(jiān)聽
mRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
/*
到達(dá)底部了,如果不加!isLoading的話到達(dá)底部如果還一滑動(dòng)的話就會(huì)一直進(jìn)入這個(gè)方法
就一直去做請(qǐng)求網(wǎng)絡(luò)的操作,這樣的用戶體驗(yàn)肯定不好.添加一個(gè)判斷,每次滑倒底只進(jìn)行一次網(wǎng)絡(luò)請(qǐng)求去請(qǐng)求數(shù)據(jù)
當(dāng)請(qǐng)求完成后,在把isLoading賦值為false,下次滑倒底又能進(jìn)入這個(gè)方法了
*/
if (newState == RecyclerView.SCROLL_STATE_IDLE && lastVisibleItem + 1 == mAdapter.getItemCount() && !isLoading) {
//到達(dá)底部之后如果footView的狀態(tài)不是正在加載的狀態(tài),就將 他切換成正在加載的狀態(tài)
if (page < totlePage) {
Log.e("duanlian", "onScrollStateChanged: " + "進(jìn)來(lái)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);
//拿到最后一個(gè)出現(xiàn)的item的位置
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
}
});重點(diǎn)就這幾個(gè),下面給出腳布局:
<?xml version="1.0" encoding="utf-8"?>
Adapter的代碼:
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{ private Context mContext; private List mList; //普通布局的type static final int TYPE_ITEM = 0; //腳布局 static final int TYPE_FOOTER = 1; // //上拉加載更多 // static final int PULL_LOAD_MORE = 0; //正在加載更多 static final int LOADING_MORE = 1; //沒(méi)有更多 static final int NO_MORE = 2; //腳布局當(dāng)前的狀態(tài),默認(rèn)為沒(méi)有更多 int footer_state = 1; public MyRecyclerAdapter(Context context, List 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) { //腳布局 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) {//如果第一個(gè)就是腳布局,,那就讓他隱藏 footViewHolder.mProgressBar.setVisibility(View.GONE); footViewHolder.tv_line1.setVisibility(View.GONE); footViewHolder.tv_line2.setVisibility(View.GONE); footViewHolder.tv_state.setText(""); } switch (footer_state) {//根據(jù)狀態(tài)來(lái)讓腳布局發(fā)生改變 // case PULL_LOAD_MORE://上拉加載 // footViewHolder.mProgressBar.setVisibility(View.GONE); // footViewHolder.tv_state.setText("上拉加載更多"); // 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("正在加載..."); 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("我是有底線的"); 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的總和,說(shuō)明是最后一個(gè)item,將它設(shè)置為腳布局 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); } } /** * 腳布局的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); } } /** * 改變腳布局的狀態(tài)的方法,在activity根據(jù)請(qǐng)求數(shù)據(jù)的狀態(tài)來(lái)改變這個(gè)狀態(tài) * * @param state */ public void changeState(int state) { this.footer_state = state; notifyDataSetChanged(); } }
activity中的代碼:
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 mList;
private List list;
private MyRecyclerAdapter mAdapter;
LinearLayoutManager linearLayoutManager;
int lastVisibleItem;
int page = 0;
boolean isLoading = false;//用來(lái)控制進(jìn)入getdata()的次數(shù)
int totlePage = 5;//模擬請(qǐng)求的一共的頁(yè)數(shù)
@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);
//給recyclerView添加滑動(dòng)監(jiān)聽
mRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
/*
到達(dá)底部了,如果不加!isLoading的話到達(dá)底部如果還一滑動(dòng)的話就會(huì)一直進(jìn)入這個(gè)方法
就一直去做請(qǐng)求網(wǎng)絡(luò)的操作,這樣的用戶體驗(yàn)肯定不好.添加一個(gè)判斷,每次滑倒底只進(jìn)行一次網(wǎng)絡(luò)請(qǐng)求去請(qǐng)求數(shù)據(jù)
當(dāng)請(qǐng)求完成后,在把isLoading賦值為false,下次滑倒底又能進(jìn)入這個(gè)方法了
*/
if (newState == RecyclerView.SCROLL_STATE_IDLE && lastVisibleItem + 1 == mAdapter.getItemCount() && !isLoading) {
//到達(dá)底部之后如果footView的狀態(tài)不是正在加載的狀態(tài),就將 他切換成正在加載的狀態(tài)
if (page < totlePage) {
Log.e("duanlian", "onScrollStateChanged: " + "進(jìn)來(lái)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);
//拿到最后一個(gè)出現(xiàn)的item的位置
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
}
});
}
/**
* 模擬請(qǐng)求數(shù)據(jù)
*/
private void getData() {
list = new ArrayList<>();
for (int i = 0; i < 10; i++) {
list.add("第" + i + "條");
}
mList.addAll(list);
isLoading = false;
mAdapter = new MyRecyclerAdapter(this, mList);
mRecycler.setAdapter(mAdapter);
}
} 看完上述內(nèi)容是否對(duì)您有幫助呢？如果還想對(duì)相關(guān)知識(shí)有進(jìn)一步的了解或閱讀更多相關(guān)文章，請(qǐng)關(guān)注創(chuàng)新互聯(lián)行業(yè)資訊頻道，感謝您對(duì)創(chuàng)新互聯(lián)的支持。
