react native 的上拉加载一直困扰着自己，一直用的第三方组件，但是可维护性不高，而且也不太好用，最近工作没那么忙，就研究下了官方的FlatList，做出来的成果，比第三方组件流畅度高好多，而且也很好用
官方介绍：https://reactnative.cn/docs/flatlist/
下面是效果图：
ios效果图
android效果图
总体思路就是：就是计算屏幕高度，然后减去导航的头部，根据列表高度计算出每页的个数,然后向上取整。这样做的目的是：防止不满屏状态下的，onEndReached函数的主动触发。
方法实现：
//满屏页面判断
fullScreenJusting(ItemHeight) {
const screnHeight = screnInfo.size.height; //屏幕高度
//计算列表个数
const listNum = (screnHeight - 40) / ItemHeight;
return Math.ceil(listNum);
}
下拉刷新用的是 RefreshControl
官网地址：https://reactnative.cn/docs/refreshcontrol/
具体代码：
import React, { Component } from 'react';
import {
View,
Text,
Image,
StyleSheet,
FlatList,
RefreshControl,
ActivityIndicator,
} from 'react-native';
import { SafeAreaView } from 'react-navigation';
import screnInfo from '../utils/View';
import BaseStyle from '../constants/Style';
import { QUESTION_LIST } from '../constants/Api';
import { form_req } from '../utils/Request';
export default class TestScreen extends Component {
constructor(props) {
super(props);
this.state = {
data: [
],
refreshing: false,
fresh: true,
animating: true,
nomore: false,
pageSize: 0,
pageNumber: 1,
};
}
componentDidMount() { //初始化的时候要判断长度 控制上拉加载
const ListNums = this.fullScreenJusting(50);
this.setState({
pageSize: ListNums
})
this.onEndReachedCalled = false;
this.getOrderList(ListNums, 1, true);
}
//满屏页面判断
fullScreenJusting(ItemHeight) {
const screnHeight = screnInfo.size.height; //屏幕高度
//计算列表个数
const listNum = (screnHeight - 40) / ItemHeight;
return Math.ceil(listNum);
}
getOrderList(ListNums, pageNumber, fresh) {
let nomore;
form_req(QUESTION_LIST, {
page: pageNumber,
perpage: ListNums,
}).then(res => {
if (res.code == 200) {
const item = res.data;
if (item.length < ListNums) {
nomore = true
} else {
nomore = false
}
if (fresh) {
this.setState({
data: item,
nomore: nomore
})
} else {
this.setState({
data: this.state.data.concat(item),
nomore: nomore,
})
}
// this.onEndReachedCalledDuringMomentum = true;
} else {
}
});
}
renderItem = item => {
return (
<View style={styles.item} key={item.id}>
<Text>{item.name}</Text>
</View>
);
};
//列表线
ItemSeparatorComponent = () => {
return <View style={styles.baseLine} />;
};
//头部
ListHeaderComponent = () => { };
//尾部
ListFooterComponent = () => {
return (
<View style={styles.bottomfoot}>
{
this.state.data.length != 0 ?
this.state.nomore ? (
<Text style={styles.footText}>- 我是有底线的 -</Text>
) : (
<View style={styles.activeLoad}>
<ActivityIndicator size="small" animating={this.state.animating} />
<Text style={[styles.footText, styles.ml]}>加载更多...</Text>
</View>
)
:
null
}
</View>
);
};
//为空时
ListEmptyComponent() {
return (
<View style={styles.noListView}>
{/* <Image
style={styles.noListImage}
source={require('../images/status/order_no_record.png')}
/> */}
<Text style={styles.NoListText}>暂无订单</Text>
</View>
);
}
_keyExtractor = (item,index) => item.id;
_onEndReached = () => {
if (!this.state.nomore && this.onEndReachedCalled ) {
this.getOrderList(this.state.pageSize, ++this.state.pageNumber, false);
}
this.onEndReachedCalled=true;
};
_onRefresh() {
this.setState({ nomore: false, pageNumber: 1 }, () => {
this.getOrderList(this.state.pageSize, 1, true);
})
}
render() {
return (
<SafeAreaView style={BaseStyle.flex}>
<View style={styles.listConten}>
<FlatList
data={this.state.data}
keyExtractor={this._keyExtractor}
onEndReached={this._onEndReached}
refreshing={true}
renderItem={({ item }) => this.renderItem(item)}
ItemSeparatorComponent={this.ItemSeparatorComponent}
ListEmptyComponent={this.ListEmptyComponent}
ListFooterComponent={this.ListFooterComponent}
onEndReachedThreshold={0.1}
refreshControl={
<RefreshControl
refreshing={this.state.refreshing}
colors={['#ff0000', '#00ff00', '#0000ff']}
progressBackgroundColor={"#ffffff"}
onRefresh={() => {
this._onRefresh();
}}
/>
}
/>
</View>
</SafeAreaView>
);
}
}
const styles = StyleSheet.create({
listConten: {
flex: 1,
backgroundColor: '#ffffff',
},
item: {
flexDirection: 'row',
justifyContent: 'center',
alignItems: "center",
backgroundColor: '#ffffff',
height: 50,
},
baseLine: {
width: screnInfo.size.width,
height: 1,
backgroundColor: '#eeeeee',
},
noListView: {
width: screnInfo.size.width,
height: screnInfo.size.height - 140,
justifyContent: 'center',
alignItems: 'center',
},
NoListText: {
marginTop: 15,
fontSize: 18,
color: '#999999',
},
noListImage: {
width: 130,
height: 140,
},
bottomfoot: {
flexDirection: 'row',
justifyContent: 'center',
alignItems: 'center',
padding: 10,
},
footText: {
marginTop: 5,
fontSize: 12,
color: '#999999',
},
activeLoad: {
flexDirection: 'row',
justifyContent: 'center',
alignItems: 'center',
},
ml: {
marginLeft: 10,
},
});
这里的坑就是：当初始化进来页面的时候 上拉会主动触发，所以这里加了一个开关 this.onEndReachedCalled = false； 初始化给一个false 当触发了 设为true,放在调取接口之后
代码都很简单易懂~ 有什么不懂的，或者有什么问题请留言，希望对大家的学习有所帮助，也希望大家多多支持。
