Android下拉刷新以及GridView使用方法详解
GridView是类似于ListView的控件，只是GridView可以使用多个列来呈现内容，而ListView是以行为单位，所以用法上是差不多的。
主布局文件，因为要做下拉刷新，所以加了一个ProgressBar，GridView的numColumns属性是指每一行有多少列
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.girdlayoutdemo.MainActivity"> <ProgressBar android:id="@+id/pb" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true"/> <GridView android:layout_below="@id/pb" android:id="@+id/gv" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_margin="5dp" android:gravity="center" android:numColumns="2"> </GridView> </RelativeLayout>
每个Item的布局文件，这里比较简单的一张图片加一段文字
<?xmlversion="1.0"encoding="utf-8"?> <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <ImageView android:id="@+id/item_iv" android:layout_width="fill_parent" android:layout_height="0dp" android:layout_weight="3"/> <TextView android:id="@+id/item_tv" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1"/> </LinearLayout>
主活动代码：
publicclassMainActivityextendsActivity{
privateGridViewgv;
privateProgressBarpb;
privateList<Map<String,Object>>list;
privateSimpleAdapteradapter;
privateGestureDetectorgsDetector;
privateHandlerhandler=newHandler(){
@Override
publicvoidhandleMessage(Messagemsg){
switch(msg.what){
case1:
pb.setVisibility(View.GONE);
Toast.makeText(MainActivity.this,"刷新成功",200).show();
break;
default:
break;
}
}
};
@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pb=(ProgressBar)findViewById(R.id.pb);
gv=(GridView)findViewById(R.id.gv);
pb.setVisibility(View.GONE);
initData();
adapter=newSimpleAdapter(this,list,R.layout.item_layout,
newString[]{"image","text"},newint[]{R.id.item_iv,
R.id.item_tv});
gv.setAdapter(adapter);
gsDetector=newGestureDetector(this,newMlistener());
gv.setOnTouchListener(newOnTouchListener(){
@Override
publicbooleanonTouch(Viewv,MotionEventevent){
//Log.e("MainActivity",event.getX()+"");
returngsDetector.onTouchEvent(event);
}
});
}
privatevoidinitData(){
list=newArrayList<Map<String,Object>>();
for(inti=0;i<20;i++){
Map<String,Object>map=newHashMap<String,Object>();
map.put("image",R.drawable.gift_item_default);
map.put("text","一只冰莹猪猪");
list.add(map);
}
}
classMlistenerimplementsOnGestureListener{
@Override
publicbooleanonDown(MotionEvente){
returnfalse;
}
@Override
publicvoidonShowPress(MotionEvente){
}
@Override
publicbooleanonSingleTapUp(MotionEvente){
returnfalse;
}
@Override
publicbooleanonScroll(MotionEvente1,MotionEvente2,
floatdistanceX,floatdistanceY){
returnfalse;
}
@Override
publicvoidonLongPress(MotionEvente){
}
@Override
publicbooleanonFling(MotionEvente1,MotionEvente2,floatvelocityX,
floatvelocityY){
if(e2.getY()-e1.getY()>0&&gv.getFirstVisiblePosition()==0){
pb.setVisibility(View.VISIBLE);
Animationanimation=newScaleAnimation(1f,1f,0,1f);
animation.setDuration(300);
pb.startAnimation(animation);
newThread(newRunnable(){
@Override
publicvoidrun(){
try{
Thread.sleep(2000);
Messagemsg=newMessage();
msg.what=1;
handler.sendMessage(msg);
}catch(InterruptedExceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
}).start();
}
returnfalse;
}
}
}
解析：
在onCreate方法中先获取两个组件，然后把progressBar设置为隐藏，下拉的时候再显示，刷新完毕再隐藏。然后为GridView设置数据源，这里方便起见用SimpleAdapter，然后给GridView设置ontouchListener，并在onTouch方法中把触摸事件交给我们自定义的GestureDetector对象来处理，在GestureDetector的onFling方法中处理下拉事件，在里面判断是否下拉以及GridView是否在最顶端，如果是，显示progressBar控件并开一个线程来处理刷新，这里做模拟就睡眠2000毫秒，最后用message对象返回一个消息给Handler，Handler在主线程中更新GridView。
@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pb=(ProgressBar)findViewById(R.id.pb);
gv=(GridView)findViewById(R.id.gv);
pb.setVisibility(View.GONE);
initData();
adapter=newSimpleAdapter(this,list,R.layout.item_layout,
newString[]{"image","text"},newint[]{R.id.item_iv,
R.id.item_tv});
gv.setAdapter(adapter);
gsDetector=newGestureDetector(this,newMlistener());
gv.setOnTouchListener(newOnTouchListener(){
@Override
publicbooleanonTouch(Viewv,MotionEventevent){
//Log.e("MainActivity",event.getX()+"");
returngsDetector.onTouchEvent(event);
}
});
}
classMlistenerimplementsOnGestureListener{
@Override
publicbooleanonDown(MotionEvente){
returnfalse;
}
@Override
publicvoidonShowPress(MotionEvente){
}
@Override
publicbooleanonSingleTapUp(MotionEvente){
returnfalse;
}
@Override
publicbooleanonScroll(MotionEvente1,MotionEvente2,
floatdistanceX,floatdistanceY){
returnfalse;
}
@Override
publicvoidonLongPress(MotionEvente){
}
@Override
publicbooleanonFling(MotionEvente1,MotionEvente2,floatvelocityX,
floatvelocityY){
if(e2.getY()-e1.getY()>0&&gv.getFirstVisiblePosition()==0){
pb.setVisibility(View.VISIBLE);
Animationanimation=newScaleAnimation(1f,1f,0,1f);
animation.setDuration(300);
pb.startAnimation(animation);
newThread(newRunnable(){
@Override
publicvoidrun(){
try{
Thread.sleep(2000);
Messagemsg=newMessage();
msg.what=1;
handler.sendMessage(msg);
}catch(InterruptedExceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
}).start();
}
returnfalse;
}
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。