ContextMenu高級用法

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關(guān)鍵字： ContextMenu

##背景

我們經(jīng)常在列表的頁面中，點(diǎn)擊列表中的行，一般進(jìn)入詳情頁面，長按列表中一行，會彈出一個菜單，包含了對某一行的操作（編輯、刪除等等），也知道通常的用法：

- 0x01. 在Activity中注冊需要上下文菜單的View：

`registerForContextMenu(mListView);`

- 0x02. 然后在Activity中繼承onCreateContextMenu方法，添加菜單項(xiàng)：

```

@Override

public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {

Log.d(LOG_TAG, "onCreateContextMenu");

super.onCreateContextMenu(menu, v, menuInfo);

menu.setHeaderTitle(R.string.prompt);

menu.add(Menu.NONE, R.id.context_menu_item_delete_record, Menu.NONE, R.string.delete_record);//groupId, itemId, order, title

menu.add(Menu.NONE, R.id.context_menu_item_delete_record_with_file, Menu.NONE, R.string.delete_record_with_file);

}```

**PS：每次長按出現(xiàn)上下文菜單都會調(diào)用這個方法**

```

/** * Called when a context menu for the {@code view} is about to

be shown. * Unlike {@link #onCreateOptionsMenu(Menu)}, this will

be called every * time the context menu is about to be shown and

should be populated for * the view (or item inside the view for {@link

AdapterView} subclasses, * this can be found in the {@code

menuInfo})). * <p> * Use {@link #onContextItemSelected(android.view.MenuItem)} to know when an

* item has been selected. * <p> * It is not safe to hold onto the

context menu after this method returns. * */

public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {

}

```

- 0x03. 接下來長按列表中一行的時候，會彈出上下文菜單：

![device-2015-11-04-141103.png](/upload/otherpic56/728306-c1f997a517d009c7.png%7Cp_w_picpathView2/2/w/1240)

- 0x04. 點(diǎn)擊菜單后，在Activity中繼承onContextItemSelected方法進(jìn)行處理：

```

@Override

public boolean onContextItemSelected(MenuItem item) {

switch (item.getItemId()){

}

```

- 0x05. 獲取Item標(biāo)識（id）

我們刪除數(shù)據(jù)庫或者一行記錄的時候，要知道主鍵（一般是id）才能進(jìn)行操作，很多人就想辦法，有的是把ListView的每個ItemView添加一個LongClickListener，然后長按的時候記錄下Position，然后在進(jìn)行相應(yīng)處理。

其實(shí)有更優(yōu)雅的做法，onContextItemSelected(MenuItem item)回調(diào)的參數(shù)item可以獲取item.getMenuInfo()，在ListView和Adapter的模式中，可以強(qiáng)制轉(zhuǎn)換成AdapterContextMenuInfo，拿到targetView（即所長按行的ItemVew，如果我們需要什么參數(shù)，直接放到View.setTag中去即可）：

```

AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();

int index = info.position;

View view = info.targetView;

```

至此，常見的用法就完了，那么遇到其他自定義View呢？

- 0x06. 自定義View的ContextMenu實(shí)現(xiàn)

下面以用到的RecycleView為例，沒有了ListView及其Adapter的封裝，我們需要自己處理ContextMenu。

最重要的是繼承View的兩個方法：

1.上下文菜單Item的附加信息（上面item.getMenuInfo()）；

```

/** * Views should implement this if they have extra information to

associate * with the context menu. The return result is supplied as a

parameter to * the {@link

OnCreateContextMenuListener#onCreateContextMenu(ContextMenu,

View, ContextMenuInfo)} * callback. * * @return Extra information

about the item for which the context menu * should be shown.

This information will vary across different * subclasses of View. */

protected ContextMenuInfo getContextMenuInfo() {

return null;

}

```

2.ViewGroup的showContextMenuForChild，每次彈出上下文菜單都會調(diào)用此方法，需要在這里更新ContextMenuInfo；

```

/** * {@inheritDoc} */

public boolean showContextMenuForChild(View originalView) {

return mParent != null && mParent.showContextMenuForChild(originalView);

}

```

- 0x07. 自定義RecycleView的ContextMenu全部代碼

```

package com.lbrant.phone.view;

import android.content.Context;

import android.support.v7.widget.RecyclerView;

import android.util.AttributeSet;

import android.util.Log;

import android.view.ContextMenu;

import android.view.View;

/**

* 作者：dell

* 時間：2015/11/3 18:34

* 文件：PhoneRecorder

* 描述：

public class ContextMenuRecyclerView extends RecyclerView {

private static final String LOG_TAG = "ContextMenuRecyclerView";

private RecyclerContextMenuInfo mContextMenuInfo = new RecyclerContextMenuInfo();

public ContextMenuRecyclerView(Context context) {

super(context);

}

public ContextMenuRecyclerView(Context context, AttributeSet attrs) {

super(context, attrs);

}

public ContextMenuRecyclerView(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

}

@Override

protected ContextMenu.ContextMenuInfo getContextMenuInfo() {

return mContextMenuInfo;

}

@Override

public boolean showContextMenuForChild(View originalView) {

Log.d(LOG_TAG, "showContextMenuForChild");

Object tag = originalView.getTag();

if (tag instanceof RecyclerItemMarker) {

mContextMenuInfo.mRecycleItemMarker = (RecyclerItemMarker) tag;

}

return super.showContextMenuForChild(originalView);

}

public static class RecyclerItemMarker {

public final int position;

public final Object obj;

public RecyclerItemMarker(int position, Object obj) {

this.position = position;

this.obj = obj;

}

public static class RecyclerContextMenuInfo implements ContextMenu.ContextMenuInfo {

public RecyclerItemMarker mRecycleItemMarker;

}

private class RecordRecycleViewAdapter extends RecyclerView.Adapter<RecordRecycleViewAdapter.RecordViewHolder> {

private Cursor mCallRecordCursor;

private int mIdIndex;

private int mPhoneNumberIndex;

private int mCallTimeIndex;

private int mDurationIndex;

private int mPathIndex;

public RecordRecycleViewAdapter(Cursor cursor) {

mCallRecordCursor = cursor;

updateCursorColumnIndex();

}

private void updateCursorColumnIndex() {

if (mCallRecordCursor != null) {

mIdIndex = mCallRecordCursor.getColumnIndex(BaseDatabaseHelper.RECORDS_COLUMNS._ID);

mPhoneNumberIndex = mCallRecordCursor.getColumnIndex(BaseDatabaseHelper.RECORDS_COLUMNS.NUMBER);

mCallTimeIndex = mCallRecordCursor.getColumnIndex(BaseDatabaseHelper.RECORDS_COLUMNS.CALL_TIME);

mDurationIndex = mCallRecordCursor.getColumnIndex(BaseDatabaseHelper.RECORDS_COLUMNS.DURATION);

mPathIndex = mCallRecordCursor.getColumnIndex(BaseDatabaseHelper.RECORDS_COLUMNS.PATH);

}

@Override

public RecordRecycleViewAdapter.RecordViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

View contentView = LayoutInflater.from(parent.getContext()).inflate(R.layout.record_list_item, parent, false);

RecordViewHolder viewHolder = new RecordViewHolder(contentView);

return viewHolder;

}

@Override

public void onBindViewHolder(RecordRecycleViewAdapter.RecordViewHolder holder, final int position) {

holder.itemView.setLongClickable(true);

if (mCallRecordCursor != null && mCallRecordCursor.moveToPosition(position)) {

long id = mCallRecordCursor.getLong(mIdIndex);

String phoneNumber = mCallRecordCursor.getString(mPhoneNumberIndex);

long seconds = mCallRecordCursor.getLong(mDurationIndex);

String callTime = mCallRecordCursor.getString(mCallTimeIndex);

String path = mCallRecordCursor.getString(mPathIndex);

String duration = String.format("%1$02d:%2$02d:%3$02d", seconds / 3600, seconds % 3600 / 60, seconds % 60);

RecordInfo info = new RecordInfo();

info.setId(id);

info.setPhoneNumber(phoneNumber);

info.setSecondsDuration(seconds);

info.setCallTime(callTime);

info.setPath(path);

holder.itemView.setTag(new ContextMenuRecyclerView.RecyclerItemMarker(position, info));

holder.mTextViewPhoneNumber.setText(phoneNumber);

holder.mTextViewDuration.setText(duration);

holder.mTextviewCallTime.setText(callTime);

Cursor cursor = queryContactByPhoneNumber(ContactsContract.CommonDataKinds.Phone.NUMBER + " = '" + phoneNumber + "'");

if (cursor != null) {

if (cursor.moveToNext()) {

long contactId = cursor.getInt(0);

Cursor contactCursor = queryContact(ContactsContract.Contacts._ID + "=" + contactId);

if (contactCursor != null) {

holder.mTextViewName.setText(contactCursor.getString(1));

contactCursor.close();

}

cursor.close();

}

@Override

public void onViewRecycled(RecordViewHolder holder) {

super.onViewRecycled(holder);

holder.itemView.setOnCreateContextMenuListener(null);

}

@Override

public int getItemCount() {

return mCallRecordCursor == null ? 0 : mCallRecordCursor.getCount();

}

public void changeCursor(Cursor cursor) {

if (cursor != mCallRecordCursor) {

if (mCallRecordCursor != null) {

mCallRecordCursor.close();

}

mCallRecordCursor = cursor;

updateCursorColumnIndex();

notifyDataSetChanged();

}

public class RecordViewHolder extends RecyclerView.ViewHolder {

private ImageView mImageViewAvatar;

private TextView mTextViewPhoneNumber;

private TextView mTextViewName;

private TextView mTextviewCallTime;

private TextView mTextViewDuration;

public RecordViewHolder(View itemView) {

super(itemView);

mImageViewAvatar = (ImageView) itemView.findViewById(R.id.p_w_picpathViewAvatar);

mTextViewName = (TextView) itemView.findViewById(R.id.textViewName);

mTextViewPhoneNumber = (TextView) itemView.findViewById(R.id.textViewPhoneNumber);

mTextviewCallTime = (TextView) itemView.findViewById(R.id.textViewCallTime);

mTextViewDuration = (TextView) itemView.findViewById(R.id.textViewDuration);

}

```

**有兩個地方需要注意：**

1.onBindViewHolder中給ItemView添加Tag;

2.設(shè)置ItemView的LongClickable為true，不然不會出現(xiàn)上下文菜單（具體原因見ContextMenu原理分析）；

holder.itemView.setLongClickable(true);

當(dāng)前題目：ContextMenu高級用法
轉(zhuǎn)載源于：http://muchs.cn/article46/gpgghg.html

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