Android中實現多行、水平滾動的分頁的Gridview執行個體源碼

功能要求：
(1)比如每頁顯示2X2，總共2XN，每個item顯示圖片+文字（點擊有連結）。
如果單行水平滾動，可以用Horizontalscrollview實現。
如果是多行水平滾動，則結合Gridview（一般是垂直滾動的）和Horizontalscrollview實現。
(2)水平滾動翻頁，下面有顯示當前頁的icon。

1.實現自訂的HorizontalScrollView(HorizontalScrollView.java)：
因為要翻頁時需要傳當前頁給調用者，所以fling函數中自己實現而不要調用父類的fling。 複製代碼 代碼如下:public class DrawerHScrollView extends HorizontalScrollView {
private static final String TAG = "DrawerHScrollView";

private IDrawerPresenter drawerPresenter = null;
private int currentPage = 0;
private int totalPages = 1;
private static Hashtable<Integer, Integer> positionLeftTopOfPages = new Hashtable();
public DrawerHScrollView(Context context) {
super(context);
}
public DrawerHScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public DrawerHScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

public void cleanup(){
currentPage = 0;
totalPages = 1;
drawerPresenter = null;
if(positionLeftTopOfPages != null){
positionLeftTopOfPages.clear();
}
}

public void setParameters(int totalPages, int currentPage, int scrollDisX) {
Log.d(TAG, "~~~~~setParameters totalPages:"+totalPages +",currentPage:"+ currentPage +",scrollDisX:"+scrollDisX);
this.totalPages = totalPages;
this.currentPage = currentPage;
positionLeftTopOfPages.clear();
for (int i = 0;i<totalPages;i++){
int posx = (scrollDisX) * i;
positionLeftTopOfPages.put(i, posx);
Log.d(TAG, "~~~~~setParameters i:"+i +",posx:"+posx);
}
smoothScrollTo(0, 0);
}

public void setPresenter(IDrawerPresenter drawerPresenter ) {
this.drawerPresenter = drawerPresenter;
}

@Override
public void fling(int velocityX) {
Log.v(TAG, "-->fling velocityX:"+velocityX);
boolean change_flag = false;
if (velocityX > 0 && (currentPage < totalPages - 1)){
currentPage++;
change_flag = true;
} else if (velocityX < 0 && (currentPage > 0)){
currentPage--;
change_flag = true;
}
if (change_flag){
int postionTo = (Integer)positionLeftTopOfPages.get(new Integer(currentPage)).intValue();
Log.v(TAG, "------smoothScrollTo posx:"+postionTo);
smoothScrollTo(postionTo, 0);
drawerPresenter.dispatchEvent(totalPages, currentPage);
}
//super.fling(velocityX);
}
}

2.布局檔案Activity_main.xml： 複製代碼 代碼如下:<com.example.multilinegridview.DrawerHScrollView
android:id="@+id/hscrollview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:scrollbars="none"
android:layout_below="@id/layout_drawer_top"
android:layout_above="@id/layout_pagenumber"
android:background="#CCCCCC" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<GridView
android:id="@+id/gridView"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</com.example.multilinegridview.DrawerHScrollView>

3.IDrawerPresenter介面(IDrawerPresenter.java)： 複製代碼 代碼如下:public interface IDrawerPresenter {
IDrawerPresenter getInstance();
void dispatchEvent(int totalPages, int currentPage);
}

4.DrawerItem 複製代碼 代碼如下:<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/layout_item"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_gravity="center"
android:background="#FFFFFF">
<ImageView
android:id="@+id/ivIcon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_launcher" />
<TextView
android:id="@+id/tvTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="優惠券1"
android:textColor="#000000"
android:textStyle="bold"/>
</LinearLayout>

5.MainActivity.java
(1)實現IDrawerPresenter介面，在HorizontalScrollView裡通過IDrawerPresenter介面來返回當前頁，從而更新pageindicator。 複製代碼 代碼如下:@Override
public IDrawerPresenter getInstance() {
return this;
}
@Override
public void dispatchEvent(int totalPages, int currentPage) {
Log.v(TAG, "~~~~dispatchEvent currentPage:" + currentPage);
Message msg = Message.obtain();
msg.what = MSG_DRAWER_UPDATE_PAGE_LAYOUT;
msg.arg1 = totalPages;
msg.arg2 = currentPage;
handler.sendMessage(msg);
}

(2)PageItemImageView和page indicator的更新
PageItemImageView顯示normal的page indicator，之後再將當前頁的圖片換成selected。 複製代碼 代碼如下:protected class PageItemImageView extends ImageView {
public PageItemImageView(Context context) {
super(context);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.icon_page_normal);
this.setImageBitmap(bitmap);
}
}
public void updateDrawerPageLayout(int total_pages, int sel_page) {
Log.e(TAG, "~~~updateBooksPageLayout total_pages:"+total_pages+",sel_page:"+sel_page);
layout_pagenumber.removeAllViews();
if (total_pages <= 0 || sel_page < 0 || sel_page >= total_pages){
Log.e(TAG, "total_pages or sel_page is outofrange.");
return;
}
for (int i = 0;i< total_pages;i++){
if (i != 0){
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.setMargins(5, 0, 0, 0);
layout_pagenumber.addView(new PageItemImageView(this), params);
} else {
layout_pagenumber.addView(new PageItemImageView(this));
}
}
PageItemImageView selItem = (PageItemImageView) layout_pagenumber.getChildAt(sel_page);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon_page_selected);
selItem.setImageBitmap(bitmap);
}

(3)DrawerListAdapter 複製代碼 代碼如下:private class DrawerListAdapter extends BaseAdapter {
private final String TAG = "MyListAdapter";
private LayoutInflater mInflater;
private LinearLayout layout_item;
private TextView tvTitle;
private ImageView ivIcon;
private final Context context;
private int colWid;
private int colHei;
public DrawerListAdapter(Context context, int colWid, int colHei) {
this.context = context;
this.colWid = colWid;
this.colHei = colHei;
mInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
return drawerItemList.size();
}
public Object getItem(int position) {
return drawerItemList.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
DrawerItem item = drawerItemList.get(position);
if (convertView == null) {
convertView = mInflater.inflate(R.layout.drawer_item, null);
layout_item = (LinearLayout) convertView
.findViewById(R.id.layout_item);
ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
tvTitle = (TextView) convertView.findViewById(R.id.tvTitle);
if (colHei != 0 && colWid != 0) {
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
colWid, colHei - 30);
ivIcon.setLayoutParams(params);
}
convertView.setTag(layout_item);
} else {
layout_item = (LinearLayout) convertView.getTag();
}
ivIcon.setImageResource(R.drawable.ic_launcher);
tvTitle.setText(String.valueOf(position));
return convertView;
}
}

(4)DrawerItemClickListener:
實現OnItemClickListener。
(5) updateDrawerLayout
獲得data的size後，可以算出列數來得到固定行。
intnumCols = (drawerItemList.size() - 1) / 2 + 1
再算出gridview的width。因每頁可顯示2列，最後一頁可能右側沒有，為了翻頁順滑，可以給gridview增加一列空白。
intgridViewWid = numCols * colWid + (numCols + 1) * spaceing;
if(numCols % 2 == 1){
gridViewWid+= colWid + spaceing;
} 複製代碼 代碼如下:public void updateDrawerLayout() {
if ((drawerItemList == null) || (drawerItemList.size() == 0)) {
Log.d(TAG, "itemList is null or empty");
return;
}
if (!hasMeasured){
Log.d(TAG, "hasMeasured is false");
return;
}
int scrollWid = hscrollview.getWidth();
int scrollHei = hscrollview.getHeight();
if (scrollWid <= 0 || scrollHei <= 0){
Log.d(TAG, "scrollWid or scrollHei is less than 0");
return;
}

int spaceing = 10;
int colWid = (scrollWid - spaceing * 3) / 2;
int colHei = (scrollHei - spaceing * 3) / 2;
int numCols = (drawerItemList.size() - 1) / 2 + 1;
int gridViewWid = numCols * colWid + (numCols + 1) * spaceing;
// if numCols is odd (like 5), add blank space
if (numCols % 2 == 1){
gridViewWid += colWid + spaceing;
}

LayoutParams params = new LayoutParams(gridViewWid, scrollHei);
gridView.setLayoutParams(params);
gridView.setColumnWidth(colWid);
gridView.setHorizontalSpacing(spaceing);
gridView.setVerticalSpacing(spaceing);
gridView.setStretchMode(GridView.NO_STRETCH);
gridView.setNumColumns(numCols);
adapter = new DrawerListAdapter(this, colWid, colHei);
listener = new DrawerItemClickListener();
gridView.setAdapter(adapter);
gridView.setOnItemClickListener(listener);
int pageNum = (drawerItemList.size() - 1) / 4 + 1;
hscrollview.setParameters(pageNum, 0, scrollWid - spaceing);
updateDrawerPageLayout(pageNum, 0);
}

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