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名师互学网 > IT > 软件开发 > 移动开发 > Android

Android下拉刷新以及GridView使用方法详解

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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

 

  

  
  



每个Item的布局文件,这里比较简单的一张图片加一段文字




  

  



主活动代码:

public class MainActivity extends Activity {
  private GridView gv;
  private ProgressBar pb;
  private List> 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>();
    for (int i = 0; i < 20; i++) {
      Map map = new HashMap();
      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;
    }

  }

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考高分网。

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