ViewPager和数据库

Question

的数据是在数据库中，所以我通常会使用的CursorAdapter，并将它与一个ListView CursorLoader工作，但是现在我需要的，而不是一个ListView一个ViewPager而这需要一个PagerAdapter我只有它有看到它与列表一起工作。

是否有使用游标或生病了，使工作本地寻呼机适配器？

谢谢！

Answer 1

基础上CursorAdapter我有与您将使用从Cursor传来的信息来实例化一个Fragment唯一的区别延伸FragmentPagerAdapter实现的内部结构。

package com.example; 

import android.content.Context; 
import android.database.Cursor; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
import android.util.SparseIntArray; 
import android.view.ViewGroup; 

import java.util.HashMap; 

public abstract class CursorFragmentPagerAdapter extends FragmentPagerAdapter { 

    protected boolean mDataValid; 
    protected Cursor mCursor; 
    protected Context mContext; 
    protected SparseIntArray mItemPositions; 
    protected HashMap<Object, Integer> mObjectMap; 
    protected int mRowIDColumn; 

    public CursorFragmentPagerAdapter(Context context, FragmentManager fm, Cursor cursor) { 
     super(fm); 

     init(context, cursor); 
    } 

    void init(Context context, Cursor c) { 
     mObjectMap = new HashMap<Object, Integer>(); 
     boolean cursorPresent = c != null; 
     mCursor = c; 
     mDataValid = cursorPresent; 
     mContext = context; 
     mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; 
    } 

    public Cursor getCursor() { 
     return mCursor; 
    } 

    @Override 
    public int getItemPosition(Object object) { 
     Integer rowId = mObjectMap.get(object); 
     if (rowId != null && mItemPositions != null) { 
      return mItemPositions.get(rowId, POSITION_NONE); 
     } 
     return POSITION_NONE; 
    } 

    public void setItemPositions() { 
     mItemPositions = null; 

     if (mDataValid) { 
      int count = mCursor.getCount(); 
      mItemPositions = new SparseIntArray(count); 
      mCursor.moveToPosition(-1); 
      while (mCursor.moveToNext()) { 
       int rowId = mCursor.getInt(mRowIDColumn); 
       int cursorPos = mCursor.getPosition(); 
       mItemPositions.append(rowId, cursorPos); 
      } 
     } 
    } 

    @Override 
    public Fragment getItem(int position) { 
     if (mDataValid) { 
      mCursor.moveToPosition(position); 
      return getItem(mContext, mCursor); 
     } else { 
      return null; 
     } 
    } 

    @Override 
    public void destroyItem(ViewGroup container, int position, Object object) { 
     mObjectMap.remove(object); 

     super.destroyItem(container, position, object); 
    } 

    @Override 
    public Object instantiateItem(ViewGroup container, int position) { 
     if (!mDataValid) { 
      throw new IllegalStateException("this should only be called when the cursor is valid"); 
     } 
     if (!mCursor.moveToPosition(position)) { 
      throw new IllegalStateException("couldn't move cursor to position " + position); 
     } 

     int rowId = mCursor.getInt(mRowIDColumn); 
     Object obj = super.instantiateItem(container, position); 
     mObjectMap.put(obj, Integer.valueOf(rowId)); 

     return obj; 
    } 

    public abstract Fragment getItem(Context context, Cursor cursor); 

    @Override 
    public int getCount() { 
     if (mDataValid) { 
      return mCursor.getCount(); 
     } else { 
      return 0; 
     } 
    } 

    public void changeCursor(Cursor cursor) { 
     Cursor old = swapCursor(cursor); 
     if (old != null) { 
      old.close(); 
     } 
    } 

    public Cursor swapCursor(Cursor newCursor) { 
     if (newCursor == mCursor) { 
      return null; 
     } 
     Cursor oldCursor = mCursor; 
     mCursor = newCursor; 
     if (newCursor != null) { 
      mRowIDColumn = newCursor.getColumnIndexOrThrow("_id"); 
      mDataValid = true; 
     } else { 
      mRowIDColumn = -1; 
      mDataValid = false; 
     } 

     setItemPositions(); 
     notifyDataSetChanged(); 

     return oldCursor; 
    } 

    @Override 
    public long getItemId(int position) { 
     if (!mDataValid || !mCursor.moveToPosition(position)) { 
      return super.getItemId(position); 
     } 
     int rowId = mCursor.getInt(mRowIDColumn); 
     return rowId; 
    } 

} 

如果你需要比片段的别的东西，你可以很容易地修改代码以您的需求。