这里有新鲜出炉的精品教程,程序狗速度看过来!
Android是一种基于Linux的自由及开放源代码的操作系统,主要使用于移动设备,如智能手机和平板电脑,由Google公司和开放手机联盟领导及开发。尚未有统一中文名称,中国大陆地区较多人使用“安卓”或“安致”。
这篇文章主要为大家详细介绍了Android下拉刷新以及GridView的使用方法,感兴趣的小伙伴们可以参考一下
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
- <RelativeLayout xmlns: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
- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns: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:
- public class MainActivity extends Activity {
- private GridView gv;
- private ProgressBar pb;
- private List < Map < String,
- Object >> list;
- private SimpleAdapter adapter;
- private GestureDetector gsDetector;
- private Handler handler = new Handler() {@Override public void handleMessage(Message msg) {
- switch (msg.what) {
- case 1:
- pb.setVisibility(View.GONE);
- Toast.makeText(MainActivity.this, "刷新成功", 200).show();
- break;
- default:
- break;
- }
- }
- };
- @Override protected void onCreate(Bundle savedInstanceState) {
- 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 = new SimpleAdapter(this, list, R.layout.item_layout, new String[] {
- "image",
- "text"
- },
- new int[] {
- R.id.item_iv,
- R.id.item_tv
- });
- gv.setAdapter(adapter);
- gsDetector = new GestureDetector(this, new Mlistener());
- gv.setOnTouchListener(new OnTouchListener() {
- @Override public boolean onTouch(View v, MotionEvent event) {
- // Log.e("MainActivity", event.getX()+"");
- return gsDetector.onTouchEvent(event);
- }
- });
- }
- private void initData() {
- list = new ArrayList < Map < String,
- Object >> ();
- for (int i = 0; i < 20; i++) {
- Map < String,
- Object > map = new HashMap < String,
- Object > ();
- map.put("image", R.drawable.gift_item_default);
- map.put("text", "一只冰莹猪猪");
- list.add(map);
- }
- }
- class Mlistener implements OnGestureListener {
- @Override public boolean onDown(MotionEvent e) {
- return false;
- }
- @Override public void onShowPress(MotionEvent e) {
- }
- @Override public boolean onSingleTapUp(MotionEvent e) {
- return false;
- }
- @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
- return false;
- }
- @Override public void onLongPress(MotionEvent e) {
- }
- @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
- if (e2.getY() - e1.getY() > 0 && gv.getFirstVisiblePosition() == 0) {
- pb.setVisibility(View.VISIBLE);
- Animation animation = new ScaleAnimation(1f, 1f, 0, 1f);
- animation.setDuration(300);
- pb.startAnimation(animation);
- new Thread(new Runnable() {@Override public void run() {
- try {
- Thread.sleep(2000);
- Message msg = new Message();
- msg.what = 1;
- handler.sendMessage(msg);
- } catch(InterruptedException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }).start();
- }
- return false;
- }
- }
- }
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
- protected void onCreate(Bundle savedInstanceState) {
- 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 = new SimpleAdapter(this, list, R.layout.item_layout,
- new String[] { "image", "text" }, new int[] { R.id.item_iv,
- R.id.item_tv });
- gv.setAdapter(adapter);
- gsDetector = new GestureDetector(this, new Mlistener());
- gv.setOnTouchListener(new OnTouchListener() {
- @Override
- public boolean onTouch(View v, MotionEvent event) {
- // Log.e("MainActivity", event.getX()+"");
- return gsDetector.onTouchEvent(event);
- }
- });
- }
- class Mlistener implements OnGestureListener {
- @Override
- public boolean onDown(MotionEvent e) {
- return false;
- }
- @Override
- public void onShowPress(MotionEvent e) {
- }
- @Override
- public boolean onSingleTapUp(MotionEvent e) {
- return false;
- }
- @Override
- public boolean onScroll(MotionEvent e1, MotionEvent e2,
- float distanceX, float distanceY) {
- return false;
- }
- @Override
- public void onLongPress(MotionEvent e) {
- }
- @Override
- public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
- float velocityY) {
- if (e2.getY() - e1.getY() > 0 && gv.getFirstVisiblePosition() == 0) {
- pb.setVisibility(View.VISIBLE);
- Animation animation = new ScaleAnimation(1f, 1f, 0, 1f);
- animation.setDuration(300);
- pb.startAnimation(animation);
- new Thread(new Runnable() {
- @Override
- public void run() {
- try {
- Thread.sleep(2000);
- Message msg = new Message();
- msg.what = 1;
- handler.sendMessage(msg);
- } catch (InterruptedException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }).start();
- }
- return false;
- }
- }
来源: http://www.phperz.com/article/17/0917/348601.html