ListView的上拉弹簧、下拉弹簧,下拉弹簧时动态带刷新和切换换刷新视图
16lz
2021-01-22
重写继承ListView后,其实本质就是两点:
(1)弹簧:利用View的scrollTo(int x, int y)方法来搞定弹簧;
(2)动态的加入和删除Header;
(3)Scroller滚动的方向和手指滑动的方向是相反的。
下面是 例子:
(1)MainActivity.class
package com.habby.sliderbar; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnClickListener; import android.widget.ArrayAdapter; import com.habby.sliderbar.SpringListView.SpringListener; public class MainActivity extends Activity implements OnClickListener { private final String TAG = getClass().getSimpleName(); private final int COMPLETED = 1; // 已完成 private SpringListView mListView = null; private SpringListener mSpringListener = null; private List<String> mDatas; private ArrayAdapter<String> mAdapter; private View mHeader1 = null; private View mHeader2 = null; private Handler mListener = new Handler() { @Override public void handleMessage(Message msg) { if (msg.what == COMPLETED) { if (mListView.getHeaderViewsCount() != 0) { mListView.removeHeaderView(mHeader2); } } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); } @Override public void onClick(View view) { switch (view.getId()) { default: break; } } private void initView() { mListView = (SpringListView) findViewById(R.id.name_lv); mDatas = new ArrayList<String>(); for (int i = 0; i < 25; ++i) { mDatas.add("fuck you"); } mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mDatas); mHeader1 = LayoutInflater.from(this).inflate(R.layout.slider_view, null); mHeader2 = LayoutInflater.from(this).inflate(R.layout.right_view, null); /** * 这应该是一个bug,必须在setAdapter之前addHeaderView,然后再removeHeaderView,这 * 样才能动态的加入和删除header。 */ mListView.addHeaderView(mHeader1); mListView.setAdapter(mAdapter); mListView.removeHeaderView(mHeader1); mSpringListener = new SpringListener() { @Override public void onSpringUpPush() { Log.e(TAG, "UpPush !"); } @Override public void onSpringDownPush() { Log.e(TAG, "DownPush"); if (mListView.getHeaderViewsCount() == 0) { mListView.addHeaderView(mHeader1); } } @Override public void onSpringCompleted() { Log.e(TAG, "Completed !"); if (mListView.getHeaderViewsCount() != 0) { mListView.removeHeaderView(mHeader1); mListView.addHeaderView(mHeader2); mListener.obtainMessage(COMPLETED).sendToTarget(); } } }; mListView.registerSpringListener(mSpringListener); } }
(2)SpringListView.class
package com.habby.sliderbar; import android.content.Context; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.widget.ListView; /** * 针对一个带上拉/下拉弹簧效果的ListView,比普通的ListView仅仅多了弹簧效果而已; * 因此,可以重写ListView,添加弹簧效果即可,其他的行为依旧是默认的ListView行为。 * 子线程用于处理 “弹回” 效果。 * @author habby */ public class SpringListView extends ListView implements Runnable { private float mLastDownY = 0f; private int mDistance = 0; // 手指/弹簧拉去移动的距离 private int mStep = 10; private boolean mPositive = false; // 滚动方向 private SpringListener mListener; public SpringListView(Context ctx, AttributeSet attrs) { super(ctx, attrs); } public SpringListView(Context ctx, AttributeSet attrs, int defStyle) { super(ctx, attrs, defStyle); } public SpringListView(Context ctx) { super(ctx); } @Override public void onFinishInflate() { } /** * 只有满足这个情况才会有下拉弹簧: * 当按下时,ListView可以显示的第1行是处于顶部第1个或底部最后1个时,下拉或上拉才有弹簧效果。 */ @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: if (getFirstVisiblePosition() == 0 || getLastVisiblePosition() == getCount() - 1) { mLastDownY = event.getY(); return true; } mDistance = 0; break; case MotionEvent.ACTION_MOVE: // 拉伸 mDistance = (int) (mLastDownY - event.getY()); if ((mDistance < 0 && (getFirstVisiblePosition() == 0)) || (mDistance > 0 && (getLastVisiblePosition() == getCount() - 1))) { mDistance /= 2; scrollTo(0, mDistance); if (mListener != null) { if (mDistance < 0) { mListener.onSpringDownPush(); } else if (mDistance > 0) { mListener.onSpringUpPush(); } } return true; } mDistance = 0; break; case MotionEvent.ACTION_UP: // 松手的时候,弹回来 if ((mDistance < 0 && getFirstVisiblePosition() == 0) || (mDistance > 0 && getLastVisiblePosition() == getCount() - 1)) { mStep = 1; mPositive = (mDistance >= 0); this.post(this); // 启动子线程,用于 "弹回" 效果 return true; } mDistance = 0; break; default: break; } // 其他情况使用ListView(父类)本身的行为,不覆盖。这里仅仅是覆盖了ListView以上的2中情况。 return super.onTouchEvent(event); } @Override public void run() { mDistance += mDistance > 0 ? -mStep : mStep; scrollTo(0, mDistance); if ((mPositive && mDistance <= 0) || (!mPositive && mDistance >= 0)) { scrollTo(0, 0); mDistance = 0; mLastDownY = 0f; if (mListener != null) { mListener.onSpringCompleted(); } return; } mStep += 5; this.postDelayed(this, 10); } public void registerSpringListener(SpringListener listener) { mListener = listener; } /** * 回调接口 */ public interface SpringListener { public void onSpringDownPush(); // 下拉 public void onSpringUpPush(); // 上拉 public void onSpringCompleted(); //"回弹" 完成 } }