Android中实现多行、水平滚动的分页的Gridview实例源码

功能要求：
(1)比如每页显示2x2，总共2xn，每个item显示图片+文字（点击有链接）。
如果单行水平滚动，可以用horizontalscrollview实现。
如果是多行水平滚动，则结合gridview（一般是垂直滚动的）和horizontalscrollview实现。
(2)水平滚动翻页，下面有显示当前页的icon。

1.实现自定义的horizontalscrollview(horizontalscrollview.java)：
因为要翻页时需要传当前页给调用者，所以fling函数中自己实现而不要调用父类的fling。

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.布局文件activity_main.xml：

<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接口(idrawerpresenter.java)：

public interface idrawerpresenter {
idrawerpresenter getinstance();
void dispatchevent(int totalpages, int currentpage);
}

4.draweritem

<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="优惠券1"
android:textcolor="#000000"
android:textstyle="bold"/>
</linearlayout>

5.mainactivity.java
(1)实现idrawerpresenter接口，在horizontalscrollview里通过idrawerpresenter接口来返回当前页，从而更新pageindicator。

@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显示normal的page indicator，之后再将当前页的图片换成selected。

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

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:
实现onitemclicklistener。
(5) updatedrawerlayout
获得data的size后，可以算出列数来得到固定行。
intnumcols = (draweritemlist.size() - 1) / 2 + 1
再算出gridview的width。因每页可显示2列，最后一页可能右侧没有，为了翻页顺滑，可以给gridview增加一列空白。
intgridviewwid = numcols * colwid + (numcols + 1) * spaceing;
if(numcols % 2 == 1){
gridviewwid+= colwid + spaceing;
}

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);
}

效果图：