recyclerview下拉重新整理和載入更多
阿新 • • 發佈：2019-02-09
SwipeRefreshLayout是google推薦的支援下拉重新整理的佈局控制元件，但是隻支援下拉重新整理不能上劃載入更多。我觀察知乎的重新整理和載入更多操作，發現他的載入更多是不需要上拉手勢的，當recyclerview滑到最後一個item時自動載入更多資料。所以我通過viewtype在recyclerview最後新增一個不同佈局的item，當這個item顯示到螢幕時自動獲取更多資料。
1. SwipeRefreshLayout
SwipeRefreshLayout包含在v4支援包中，使用很簡單，佈局：
<android.support.v4.widget.SwipeRefreshLayout java程式碼中，設定重新整理監聽setOnRefreshListener，通過setRefreshing(false)關閉重新整理動畫：
mSwipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swiperefresh);
mSwipeRefreshLayout.setOnRefreshListener(new 效果：
2. 通過viewtype使recyclerview顯示不同佈局
1. 定義兩個ViewHolder類來顯示不同佈局：
protected class MyViewHolder extends RecyclerView.ViewHolder {
TextView mTextView1;
public MyViewHolder(View itemView) {
super(itemView);
mTextView1= (TextView) itemView.findViewById(R.id.text);
}
}
protected class LastViewHolder extends RecyclerView.ViewHolder{
public LastViewHolder(View itemView) {
}
}2. 重寫getItemCount和getItemViewType方法，要注意的是getItemCount返回的數量要比資料量+1：
@Override
public int getItemCount() {
return mList.size()+1;
}
@Override
public int getItemViewType(int position) {
if (position==mList.size()){
return 2;
}else {
return 1;
}
}3. 在onCreateViewHolder和onBindViewHolder中分情況處理：
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType==1){
View view = mInflater.inflate(R.layout.item,parent,false);
MyViewHolder holder= new MyViewHolder(view);
return holder;
}else {
View view = mInflater.inflate(R.layout.last_item,parent,false);
LastViewHolder holder=new LastViewHolder(view);
return holder;
}
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MyViewHolder){
((MyViewHolder) holder).mTextView1.setText(mList.get(position)+position);
}else if (holder instanceof LastViewHolder){
getMore();
}
}顯示效果：
3. 實現當顯示最後item時載入更多
1. 為了能在activity中實現載入更多的操作，需要把adapter設為抽象類，並定義抽象方法
abstract void getMore();2. 在onBindViewHolder中呼叫getMore();
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MyViewHolder){
((MyViewHolder) holder).mTextView1.setText(mList.get(position)+position);
}else if (holder instanceof LastViewHolder){
getMore();
}
}3. 在初始化adapter時實現getMore()方法，但是這時候還不能直接呼叫notifyDataSetChanged()，所以使用handl來進行處理：
final Adapter adapter= new Adapter(mList, this) {
@Override
void getMore() {
mHandler.sendMessage(new Message());
}
};
mHandler=new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message msg) {
mList.add("adfjyagjkjgjkukhuhk");
adapter.notifyDataSetChanged();
return false;
}
});效果：
完整程式碼：
adapter：
public abstract class Adapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
List<String> mList;
Context mContext;
LayoutInflater mInflater;
public Adapter(List<String> list, Context context) {
mList = list;
mContext = context;
mInflater=LayoutInflater. from(mContext);
}
@Override
public int getItemCount() {
return mList.size()+1;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType==1){
View view = mInflater.inflate(R.layout.item,parent,false);
MyViewHolder holder= new MyViewHolder(view);
return holder;
}else {
View view = mInflater.inflate(R.layout.last_item,parent,false);
LastViewHolder holder=new LastViewHolder(view);
return holder;
}
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MyViewHolder){
((MyViewHolder) holder).mTextView1.setText(mList.get(position)+position);
}else if (holder instanceof LastViewHolder){
getMore();
}
}
@Override
public int getItemViewType(int position) {
if (position==mList.size()){
return 2;
}else {
return 1;
}
}
protected class MyViewHolder extends RecyclerView.ViewHolder {
TextView mTextView1;
public MyViewHolder(View itemView) {
super(itemView);
mTextView1= (TextView) itemView.findViewById(R.id.text);
}
}
protected class LastViewHolder extends RecyclerView.ViewHolder{
public LastViewHolder(View itemView) {
super(itemView);
}
}
abstract void getMore();
}mainactivity：
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private SwipeRefreshLayout mSwipeRefreshLayout;
List<String> mList;
static private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView= (RecyclerView) findViewById(R.id.recycleview);
mList=new ArrayList<>();
for (int i = 0; i < 25; i++) {
mList.add("akudfhakjnk");
}
final Adapter adapter= new Adapter(mList, this) {
@Override
void getMore() {
mHandler.sendMessage(new Message());
}
};
mHandler=new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message msg) {
mList.add("adfjyagjkjgjkukhuhk");
adapter.notifyDataSetChanged();
return false;
}
});
mRecyclerView.setAdapter(adapter);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));
mSwipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swiperefresh);
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
mList.add(0,"ajkfgamj");
mSwipeRefreshLayout.setRefreshing(false);
adapter.notifyDataSetChanged();
}
});
}
}