之前和大家探討過 如何使用ListView實現GridView，最近利用空閒時間寫了一份代碼。分享給大家，如果有什麼問題，可以聯繫我。QQ157688302
請在本文最後下載此類，使用方法如下：
- GridAdapter<T> mAdapter = new GridAdapter<T>(getApplicationContext(), adapter);
- mAdapter.setNumColumns(3);
- mAdapter.setOnItemClickListener(new OnGridItemClickListener() {
- @Override
- public void onItemClick(int pos, int realPos) {
- //這裏的Listener需要自己擴充，可以callback你需要的內容。
- }
- });
- list.setAdapter(mAdapter);
/**
* Wrapper adapter and make it like GridView
* <hr>
* notice : {@link OnGridItemClickListener} instead of
* {@link OnItemClickListener} <br>
* e.g: use {@link #setOnItemClickListener(OnGridItemClickListener)} instead of
* {@link ListView#setOnItemClickListener(OnItemClickListener)}
*
* @author Chaos
* @date 2013-2-21
*/
public class GridAdapterWrapper<T extends BaseAdapter> extends BaseAdapter implements OnClickListener
{
private static final AtomicInteger sNextGeneratedId = new AtomicInteger(1);
private static final int ID_POS = fakeGenId();
private static final int ID_REAL_POS = fakeGenId();
/**
* The wrapper content --> adapter
*/
private T mAdapter = null;
/**
* The number columns
*/
private int mColumns = 2;
/**
* The real onItemClickListener
*/
private OnGridItemClickListener mGridListener;
/**
* The Context Object
*/
private Context mContext;
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (mColumns == 1) {
View child = mAdapter.getView(position, convertView, parent);
setOnItemClickListenerIfNeed(child, position, position);
//no need
return child;
}
return bindGridView(position, convertView, parent);
}
protected View bindGridView(int position, View convertView, ViewGroup parent) {
ViewGroup root = null;
//cache the root
if (convertView == null || !(convertView instanceof ViewGroup)) {
root = createRoot();
root.setClickable(false);
root.setFocusable(false);
}
else {
root = (ViewGroup) convertView;
}
//columns = 3
//pos --> real pos
//0 --> 0 1 2
//1 --> 3 4 5
//2 --> 6 7 8
//so do this
return bindView(root, position);
}
protected ViewGroup bindView(ViewGroup root, int pos) {
final int count = mAdapter.getCount();
final int childCount = root.getChildCount();
for (int i = 0; i < mColumns; i++) {
// real position
int index = mColumns * pos + i;
// 不足一行時，直接返回現有狀態
if (index == count) {
// fix bug : root是有可能是系統緩存的root，這裏直接返回root將導致如果此行數量
// 不夠columns，就會使用緩存的root裏的child，爲了避免這個問題，必須
// 將緩存的child移除。
// by Chaos at 2012-12-17
removeCacheChild(root, index);
break;
}
else if (index > count) {
throw new UnknownError("unknowError");
}
View child = mAdapter.getView(index, root.getChildAt(i), root);
setOnItemClickListenerIfNeed(child, pos, index);
if (childCount == mColumns) {
// root已經包含了Item，就沒有必要繼續添加了。
continue;
}
else {
if (i == 0 && childCount != 0) {
// 如果root已經包含item，但是並不全，這裏就移除重新添加
// FIXME 也許還有更好的方案
root.removeAllViews();
}
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
// LinearLayout.LayoutParams.WRAP_CONTENT,
mContext.getResources().getDisplayMetrics().widthPixels / mColumns, LinearLayout.LayoutParams.WRAP_CONTENT);
child.setFocusable(true);
child.setClickable(true);
if (child instanceof ViewGroup) {
((ViewGroup) child).setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
}
root.addView(child, lp);
}
}
return root;
}
/**
* remove child view in cache of root
*/
private void removeCacheChild(ViewGroup root, int index) {
int realColumns = (index - 1) % mColumns;
int moveCount = (mColumns - 1) - realColumns;
for (int i = 0; i < moveCount; i++) {
final View child = root.getChildAt((mColumns - 1 - i));
if (child != null) {
root.removeView(child);
}
}
}
/**
* create root for item of ListView
*/
protected ViewGroup createRoot() {
LinearLayout root = new LinearLayout(mContext);
root.setOrientation(LinearLayout.HORIZONTAL);
LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
root.setLayoutParams(lp);
return root;
}
private boolean setOnItemClickListenerIfNeed(View child, int pos, int realPos) {
if (mGridListener == null) {
return false;
}
child.setOnClickListener(this);
child.setTag(ID_POS, pos);
child.setTag(ID_REAL_POS, realPos);
return true;
}
public void setOnItemClickListener(OnGridItemClickListener listener) {
this.mGridListener = listener;
}
public void setNumColumns(int columns) {
this.mColumns = columns;
}
public int getNumColumns() {
return mColumns;
}
public GridAdapterWrapper(Context context, T adapter) {
this.mContext = context;
this.mAdapter = adapter;
}
@Override
public int getCount() {
int count = (int) Math.ceil(mAdapter.getCount() / (double) mColumns);
return count;
}
@Override
public Object getItem(int position) {
return mAdapter.getItem(position);
}
@Override
public long getItemId(int position) {
return mAdapter.getItemId(position);
}
@Override
public boolean hasStableIds() {
return mAdapter.hasStableIds();
}
@Override
public void registerDataSetObserver(DataSetObserver observer) {
mAdapter.registerDataSetObserver(observer);
}
@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
mAdapter.unregisterDataSetObserver(observer);
}
@Override
public boolean areAllItemsEnabled() {
return mAdapter.areAllItemsEnabled();
}
@Override
public boolean isEnabled(int position) {
return mAdapter.isEnabled(position);
}
@Override
public int getItemViewType(int position) {
return mAdapter.getItemViewType(position);
}
@Override
public int getViewTypeCount() {
return mAdapter.getViewTypeCount();
}
@Override
public boolean isEmpty() {
return mAdapter.isEmpty();
}
public T getWrappedAdapter() {
return mAdapter;
}
public static interface OnGridItemClickListener
{
public void onItemClick(int pos, int realPos);
}
@Override
public void onClick(View v) {
if (mGridListener == null) {
//no need to feedback
}
int pos = (Integer) v.getTag(ID_POS);
int realPos = (Integer) v.getTag(ID_REAL_POS);
mGridListener.onItemClick(pos, realPos);
}
/**
* copy from {@link View#generateViewId()} <br>
*
* @since API 17
* @return
*/
public static int generateViewId() {
for (;;) {
final int result = sNextGeneratedId.get();
// aapt-generated IDs have the high byte nonzero; clamp to the range
// under that.
int newValue = result + 1;
if (newValue > 0x00FFFFFF) {
newValue = 1; // Roll over to 1, not 0.
}
if (sNextGeneratedId.compareAndSet(result, newValue)) {
return result;
}
}
}
/**
* 生成一個ID，讓系統誤以爲是 {@link R}中的id
*
* @return
*/
public static int fakeGenId() {
int realId = generateViewId();
int fakeId = realId | 0x10000000;
return fakeId;
}
}
