ListView实现下拉动态渲染数据

constructor(props) {
 super(props);

 this.ds = new ListView.DataSource({rowHasChanged: (r1, r2) => r1 !== r2});
 this.state = {
  dataSource:this.ds,
 }

 this.listData = null; //数据源
 this.len = null; //数据的个数
 this.count = null; //当前数据总页数
 this.pageSize = 10; //每次渲染的个数
 this.page = 0; //当前页数
}

componentDidMount() {
 fetch('http://ued.yihaodian.com:3001/api/70')
  .then((response) => response.json())
  .then((data) => {
  this.listData = data.listData;
  this.len = this.listData.length;
  this.count = Math.ceil(this.len / this.pageSize);

  this.setState({
   dataSource:this.ds.cloneWithRows(this.setData())
  })
  })
  .done();
}

setData(){
 let num = this.page * this.pageSize; //获取要渲染的个数
 if(num>this.len) num = this.len; //如果到最后一页 num 大于 len 那么num等于len 防止空数据

 let data = [];
 for(let i=0;i<num;i++){
  data.push(this.listData[i]);
 }
 return data;
}

//当列表被滚动到距离最底部不足onEndReachedThreshold个像素的距离时调用
onEndReached = {this.onEnd.bind(this)}

onEnd(){
 //如果page<count 那么我们让page++ 重新设置dataSource
 if(this.page < this.count){
  this.page++;
  if(this.setData().length > 0){ //防止重复渲染
  this.setState({
   dataSource:this.ds.cloneWithRows(this.setData())
  })
  }
 }else{
  console.log('已经是最后一页了');
  return false;
 }
}

render() {
 return (
  <ListView
   style={{height:Dimensions.get('window').height-109}}
   dataSource={this.state.dataSource}
   renderRow={this.rendList} 
   onEndReached={this.onEnd.bind(this)}
   onEndReachedThreshold={0}
   enableEmptySections={true} />
 );
}