RecyclerView+ContextMenu实现的技术难点主要是在RecyclerView中获取被点击item的position，本文一共给出了两种解决方案：
方案一：
从onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo)方法传递进来的menuInfo中获取到相应的position信息。
方案二：
从RecyclerView的Adapter入手，在Adapter的ViewHolder中为每个itemView设置setOnLongClickListener监听，然后在长按监听回调中设置当前的position，为每个itemView设置setOnCreateContextMenuListener监听，通过上面记录的position来执行相应的动作。
一、方案一实现步骤：
RecyclerView+ContextMenu实现菜单项和ListView添加ContextMenu的步骤差不多，但要注意的是，从onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo)方法传递进来的menuInfo为null，为什么为null值呢？因为RecyclerView并没有像ListView一样给我们重写View.getContextMenuInfo()这个方法，所以返回的是默认值null,（翻翻源码很容易就找到了），所以我们可以参考AbsListView类中对mContextMenuInfo对象的相关操作，重载RecyclerView类的showContextMenuForChild和getContextMenuInfo方法派生RecyclerViewWithContextMenu类。其中，在showContextMenuForChild方法中通过RecyclerView对应的LayoutManager方法获取到item的位置信息，并赋值给自定义的菜单附加信息类的对象。然后，在getContextMenuInfo方法中返回这个对象。这样上下文菜单被创建的时候就会在onCreateContextMenu方法的menuInfo对象中获得到传递的附加信息。
1.1 在RecyclerView中的的item布局设置longClickable属性
在RecyclerView中的的item布局设置longClickable属性，这样在长按item的时候才能弹出ContextMenu。注意：必须而且仅能在最外层布局中设置允许长按。
//代码设置
rl.setLongClickable(true);
//xml中设置
android:longClickable="true"
1.2 重载onCreateContextMenu
可以Activity中使用registerForContextMenu(view)注册需要上下文菜单的View,然后重载onCreateContextMenu方法，也可以在需要用到上下文菜单的View中设置setOnCreateContextMenuListener监听器来监听onCreateContextMenu事件的产生。这两种方法都可以实现，只要用其中一种即可。
方法一：registerForContextMenu(view)
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
registerForContextMenu(mRvUserList);
...
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
RecyclerViewWithContextMenu.RecyclerViewContextInfo contextMenuInfo = (RecyclerViewWithContextMenu.RecyclerViewContextInfo) menuInfo;
if(contextMenuInfo!=null && contextMenuInfo.getPosition()>=0){
UserAdapter adapter=(UserAdapter)mRvUserList.getAdapter();
mSelectModelUser = adapter.getItem(contextMenuInfo.getPosition());
menu.setHeaderTitle(mSelectModelUser.getUserName());
CreateMenu(menu);
}
}
public void CreateMenu(Menu menu)
{
int groupID = 0;
int order = 0;
int[] itemID = {1,2};
for(int i=0;i<itemID.length;i++)
{
switch(itemID[i])
{
case 1:
menu.add(groupID, itemID[i], order, "编辑");
break;
case 2:
menu.add(groupID, itemID[i], order, "删除");
break;
default:
break;
}
}
}
方法二：view…setOnCreateContextMenuListener
mRvUserList.setOnCreateContextMenuListener(new View.OnCreateContextMenuListener() {
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
RecyclerViewWithContextMenu.RecyclerViewContextInfo contextMenuInfo = (RecyclerViewWithContextMenu.RecyclerViewContextInfo) menuInfo;
if(contextMenuInfo!=null && contextMenuInfo.getPosition()>=0){
UserAdapter adapter=(UserAdapter)mRvUserList.getAdapter();
mSelectModelUser = adapter.getItem(contextMenuInfo.getPosition());
menu.setHeaderTitle(mSelectModelUser.getUserName());
CreateMenu(menu);
}
}
});
1.3 重载onContextItemSelected方法
@Override
public boolean onContextItemSelected(MenuItem item) {
switch (item.getItemId()) {
case 1:
showMsg("编辑");
break;
case 2:
showMsg("删除");
break;
default:
break;
}
return super.onContextItemSelected(item);
}
1.4 RecyclerViewWithContextMenu
public class RecyclerViewWithContextMenu extends RecyclerView {
private RecyclerViewContextInfo mContextInfo = new RecyclerViewContextInfo();
public RecyclerViewWithContextMenu(Context context) {
super(context);
}
public RecyclerViewWithContextMenu(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
public RecyclerViewWithContextMenu(Context context, @Nullable AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
public boolean showContextMenuForChild(View originalView) {
getPositionByChild(originalView);
return super.showContextMenuForChild(originalView);
}
@Override
public boolean showContextMenuForChild(View originalView, float x, float y) {
getPositionByChild(originalView);
return super.showContextMenuForChild(originalView, x, y);
}
/**
* 记录当前RecyclerView中Item上下文菜单的Position
* @param originalView originalView
*/
private void getPositionByChild(View originalView){
LayoutManager layoutManager =getLayoutManager();
if(layoutManager!=null){
int position=layoutManager.getPosition(originalView);
mContextInfo.setPosition(position);
}
}
@Override
protected ContextMenu.ContextMenuInfo getContextMenuInfo() {
return mContextInfo;
}
public class RecyclerViewContextInfo implements ContextMenu.ContextMenuInfo {
private int mPosition = -1;
public int getPosition(){
return this.mPosition;
}
public int setPosition(int position){
return this.mPosition=position;
}
}
}
1.5 UserAdapter
public class UserAdapter extends RecyclerView.Adapter<UserAdapter.ViewHolder>{
private Context mContext;
private List<ModelUser> mList;
public UserAdapter(List<ModelUser> fruitList){this.mList=fruitList;}
public void setAdapterList(List<ModelUser> fruitList){this.mList=fruitList;}
@Override
public UserAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if(mContext==null){
mContext = parent.getContext();
}
View view= LayoutInflater.from(mContext).inflate(R.layout.item_user_list_layout,parent,false);
final ViewHolder holder=new ViewHolder(view);
return holder;
}
@Override
public void onViewRecycled(ViewHolder holder) {
super.onViewRecycled(holder);
}
@Override
public void onBindViewHolder(final UserAdapter.ViewHolder holder, int position) {
ModelUser user = mList.get(position);
holder.mUserName.setText(user.getUserName());
holder.mUserDesc.setText(user.getCreateDate().toString());
}
@Override
public int getItemCount() {
return mList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
CardView mCardView;
ImageView mImageView;
TextView mUserName;
TextView mUserDesc;
public ViewHolder(View view){
super(view);
mCardView = (CardView) view;
mImageView= (ImageView) view.findViewById(R.id.iv_user_image);
mUserName = (TextView) view.findViewById(R.id.tv_user_name);
mUserDesc = (TextView) view.findViewById(R.id.tv_user_desc);
}
}
public ModelUser getItem(int position) {
if (mList != null && (mList.size() >= position)) {
return mList.get(position);
}
return null;
}
}
显示的效果：
二、方案二实现步骤：
方案二要比方案一步骤简单不少，不需要设置longClickable属性，不需要registerForContextMenu(view)，在Activity中只需要重载onContextItemSelected(MenuItem item)就可以了，剩下的都在Adapter中实现了。
2.1 在Activity中重载onContextItemSelected
@Override
public boolean onContextItemSelected(MenuItem item) {
switch (item.getItemId()) {
case 1:
showMsg("编辑");
break;
case 2:
showMsg("删除");
break;
default:
break;
}
return super.onContextItemSelected(item);
}
2.2 在 adapter 中创建 position 变量，并设置 set/get 方法来操作当前 item 的 position
private int position;
public int getContextMenuPosition() { return position; }
public void setContextMenuPosition(int position) { this.position = position; }
2.3 在 ViewHolder 中 实现 OnCreateContextMenuListener 接口
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnCreateContextMenuListener{
CardView mCardView;
ImageView mImageView;
TextView mUserName;
TextView mUserDesc;
public ViewHolder(View view){
super(view);
mCardView = (CardView) view;
mImageView= (ImageView) view.findViewById(R.id.iv_user_image);
mUserName = (TextView) view.findViewById(R.id.tv_user_name);
mUserDesc = (TextView) view.findViewById(R.id.tv_user_desc);
view.setOnCreateContextMenuListener(this);
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
//注意传入的menuInfo为null
ModelUser mSelectModelUser = mList.get(getContextMenuPosition());
Log.i("UserAdapter", "onCreateContextMenu: "+getContextMenuPosition());
menu.setHeaderTitle(mSelectModelUser.getUserName());
((UserActivity)mContext).CreateMenu(menu);
}
}
2.4 在 onBindViewHolder 方法中添加 OnLongClickListener 监听，保存当前 item 的 position。
@Override
public void onBindViewHolder(final UserAdapter.ViewHolder holder, int position) {
ModelUser user = mList.get(position);
holder.mUserName.setText(user.getUserName());
holder.mUserDesc.setText(user.getCreateDate().toString());
holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
setContextMenuPosition(holder.getLayoutPosition());
return false;
}
});
}
2.5 在 onViewRecycled 方法中移除 OnLongClickListener 监听
@Override
public void onViewRecycled(ViewHolder holder) {
holder.itemView.setOnLongClickListener(null);
super.onViewRecycled(holder);
}
完整的UserAdapter如下：
public class UserAdapter extends RecyclerView.Adapter<UserAdapter.ViewHolder>{
private Context mContext;
private List<ModelUser> mList;
private int position;
public int getContextMenuPosition() { return position; }
public void setContextMenuPosition(int position) { this.position = position; }
public UserAdapter(List<ModelUser> fruitList){this.mList=fruitList;}
public void setAdapterList(List<ModelUser> fruitList){this.mList=fruitList;}
@Override
public UserAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if(mContext==null){
mContext = parent.getContext();
}
View view= LayoutInflater.from(mContext).inflate(R.layout.item_user_list_layout,parent,false);
final ViewHolder holder=new ViewHolder(view);
return holder;
}
@Override
public void onViewRecycled(ViewHolder holder) {
holder.itemView.setOnLongClickListener(null);
super.onViewRecycled(holder);
}
@Override
public void onBindViewHolder(final UserAdapter.ViewHolder holder, int position) {
ModelUser user = mList.get(position);
holder.mUserName.setText(user.getUserName());
holder.mUserDesc.setText(user.getCreateDate().toString());
holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
setContextMenuPosition(holder.getLayoutPosition());
return false;
}
});
}
@Override
public int getItemCount() {
return mList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnCreateContextMenuListener{
CardView mCardView;
ImageView mImageView;
TextView mUserName;
TextView mUserDesc;
public ViewHolder(View view){
super(view);
mCardView = (CardView) view;
mImageView= (ImageView) view.findViewById(R.id.iv_user_image);
mUserName = (TextView) view.findViewById(R.id.tv_user_name);
mUserDesc = (TextView) view.findViewById(R.id.tv_user_desc);
view.setOnCreateContextMenuListener(this);
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
//注意传入的menuInfo为null
ModelUser mSelectModelUser = mList.get(getContextMenuPosition());
Log.i("UserAdapter", "onCreateContextMenu: "+getContextMenuPosition());
menu.setHeaderTitle(mSelectModelUser.getUserName());
((UserActivity)mContext).CreateMenu(menu);
}
}
}
显示的效果：
版权声明：本文为MakerCloud原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接和本声明。