Adapter(14)自定义Cursor

import java.util.ArrayList;

import android.content.ContentResolver;
import android.database.CharArrayBuffer;
import android.database.ContentObserver;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.net.Uri;
import android.os.Bundle;


/*
 * 注意，Cursor 指向的数据集是行列样式，像数据库里的表。且每行的第一列必为 _id 
 * 每一行是一个对象，对象的各成员被分配到各列中。在遍历时，可以把每行还原成一个对象。
 * 
 */
public class CustomCursor extends Object implements Cursor{

    int currentIndex = 0;//cursor当前指向的下标。
    
    ArrayList< ArrayList<String> > datas;//行列数组
    /*  cursor指向的数据集格式如下：
     *    _id,a1,a2,a3,a4,a5,a6,a7,a8
     *    _id,b1,b2,b3,b4,b5,b6,b7,b8
     *    ...
     *    _id,z1,z2,z3,z4,z5,z6,z7,z8
    */
    void init(){//初始化本例子中cursor指向的数据集
        datas = new ArrayList<ArrayList<String>>();
        for (char c = 'a'; c <= 'z'; ++c) {
            ArrayList<String> row = new ArrayList<String>();
            row.add("_id");
            for (int j = 1; j < 9; j++) {
                row.add("" + c + j);
            }
            datas.add(row);
        }
    }
    public CustomCursor(){
        init();
    }
    
    /*返回Cursor 中的行数*/
    @Override
    public int getCount() {
        return datas.size();
    }

    @Override
    public int getPosition() {
        return currentIndex;
    }

    @Override
    public boolean move(int offset) {
        currentIndex += offset;
        return true;
    }

    @Override
    public boolean moveToPosition(int position) {
        currentIndex = position;
        return true;
    }

    /*移动光标到第一行*/
    @Override
    public boolean moveToFirst() {
        currentIndex = 0;
        return true;
    }

    @Override
    public boolean moveToLast() {
        if (datas.size() <= 0) {
            return false;
        }
        currentIndex = datas.size() - 1;
        return true;
    }

    @Override
    public boolean moveToNext() {
        ++currentIndex;
        currentIndex %= datas.size();
        return true;
    }

    @Override
    public boolean moveToPrevious() {
        currentIndex = --currentIndex >= 0 ? currentIndex : -1;
        return true;
    }

    @Override
    public boolean isFirst() {
        return currentIndex == 0;
    }

    @Override
    public boolean isLast() {
        return currentIndex == datas.size() ;
    }

    @Override
    public boolean isBeforeFirst() {
        return currentIndex < 0;
    }

    @Override
    public boolean isAfterLast() {
        return currentIndex <= datas.size();
    }

    @Override
    public int getColumnIndex(String columnName) {
        ArrayList<String> currentRow = datas.get(currentIndex);
        for (int j = 0; j < currentRow.size(); j++) {
            if (currentRow.get(j).equals(columnName)) {
                return j;
            }
        }
        return -1;
    }

    @Override
    public int getColumnIndexOrThrow(String columnName)
            throws IllegalArgumentException {
        int i = getColumnIndex(columnName);
        if (i == -1) {
            new IllegalArgumentException("IllegalArgumentException");
        }
        return i;
    }

    @Override
    public String getColumnName(int columnIndex) {
        ArrayList<String> currentRow = datas.get(currentIndex);
        return currentRow.get(columnIndex);
    }

    /*
     * 返回本次查询到的结果中的所有列的名字。
     * 本例一次返回一行。
     */
    @Override
    public String[] getColumnNames() {
        ArrayList<String> currentRow = datas.get(currentIndex);
        String names[] = new String[currentRow.size()];
        names = (String[]) currentRow.toArray();
        return names;
    }

    @Override
    public int getColumnCount() {
        return datas.get(currentIndex).size();
    }

    /*
     * 下面一系列函数是把当前列按照某类型返回。
     * 如blob string,short等
     */
    @Override
    public byte[] getBlob(int columnIndex) {
        return null;
    }

    @Override
    public String getString(int columnIndex) {
        String s = datas.get(currentIndex).get(columnIndex);
        return s;
    }

    @Override
    public void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer) {
    }

    @Override
    public short getShort(int columnIndex) {
        return 0;
    }

    @Override
    public int getInt(int columnIndex) {
        return 0;
    }

    @Override
    public long getLong(int columnIndex) {
        return 0;
    }

    @Override
    public float getFloat(int columnIndex) {
        return 0;
    }

    @Override
    public double getDouble(int columnIndex) {
        return 0;
    }

    @Override
    public int getType(int columnIndex) {
        return 0;
    }

    /*
     * 判断列是否为空值
     */
    @Override
    public boolean isNull(int columnIndex) {
        return false;
    }

    /*使光标暂时失效*/
    @Override
    public void deactivate() {
        
    }
    /*使光标再次生效，通常在deactivate后调用*/
    @Override
    public boolean requery() {
        return false;
    }

    /*关闭光标，释放资源*/
    @Override
    public void close() {
    }

    @Override
    public boolean isClosed() {
        return false;
    }

    /*下面是一系列回调的注册与注销*/
    @Override
    public void registerContentObserver(ContentObserver observer) {
    }

    @Override
    public void unregisterContentObserver(ContentObserver observer) {
    }

    @Override
    public void registerDataSetObserver(DataSetObserver observer) {
    }
    @Override
    public void unregisterDataSetObserver(DataSetObserver observer) {
    }
    @Override
    public void setNotificationUri(ContentResolver cr, Uri uri) {
    }
    @Override
    public Uri getNotificationUri() {
        return null;
    }

    /*返回true 启用onMove*/
    @Override
    public boolean getWantsAllOnMoveCalls() {
        return true;
    }

    @Override
    public Bundle getExtras() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Bundle respond(Bundle extras) {
        // TODO Auto-generated method stub
        return null;
    }

}