写代码的四点:
1.明确需求。要做什么?
2.分析思路。要怎么做?(1,2,3……)
3.确定步骤。每一个思路要用到哪些语句、方法和对象。
4.代码实现。用具体的语言代码将思路实现出来。
学习新技术的四点:
1.该技术是什么?
2.该技术有什么特点?(使用需注意的方面)
3.该技术怎么使用?(写Demo)
4.该技术什么时候用?(在Project中的使用场景 )
----------------------早计划,早准备,早完成。-------------------------
代码如下:
package com.wy.test.other; import android.content.Context; import android.database.DataSetObserver; import android.graphics.Rect; import android.util.AttributeSet; import android.view.GestureDetector; import android.view.GestureDetector.OnGestureListener; import android.view.MotionEvent; import android.view.View; import android.widget.AdapterView; import android.widget.ListAdapter; import android.widget.Scroller; import java.util.LinkedList; import java.util.Queue; /** * 横向滑动的ListView(滑动和点击冲突已经解决) */ public class HorizontalListView extends AdapterView<ListAdapter> { float startX; float startY; public boolean mAlwaysOverrideTouch = true; protected ListAdapter mAdapter; private int mLeftViewIndex = -1; private int mRightViewIndex = 0; protected int mCurrentX; protected int mNextX; private int mMaxX = Integer.MAX_VALUE; private int mDisplayOffset = 0; protected Scroller mScroller; private GestureDetector mGesture; private Queue<View> mRemovedViewQueue = new LinkedList<View>(); private OnItemSelectedListener mOnItemSelected; private OnItemClickListener mOnItemClicked; private OnItemLongClickListener mOnItemLongClicked; private boolean mDataChanged = false; public HorizontalListView(Context context, AttributeSet attrs) { super(context, attrs); initView(); } private synchronized void initView() { mLeftViewIndex = -1; mRightViewIndex = 0; mDisplayOffset = 0; mCurrentX = 0; mNextX = 0; mMaxX = Integer.MAX_VALUE; mScroller = new Scroller(getContext()); mGesture = new GestureDetector(getContext(), mOnGesture); } @Override public void setOnItemSelectedListener(OnItemSelectedListener listener) { mOnItemSelected = listener; } @Override public void setOnItemClickListener(OnItemClickListener listener) { mOnItemClicked = listener; } @Override public void setOnItemLongClickListener(OnItemLongClickListener listener) { mOnItemLongClicked = listener; } private DataSetObserver mDataObserver = new DataSetObserver() { @Override public void onChanged() { synchronized (HorizontalListView.this) { mDataChanged = true; } invalidate(); requestLayout(); } @Override public void onInvalidated() { reset(); invalidate(); requestLayout(); } }; @Override public ListAdapter getAdapter() { return mAdapter; } @Override public View getSelectedView() { return null; } @Override public void setAdapter(ListAdapter adapter) { if (mAdapter != null) { mAdapter.unregisterDataSetObserver(mDataObserver); } mAdapter = adapter; mAdapter.registerDataSetObserver(mDataObserver); reset(); } private synchronized void reset() { initView(); removeAllViewsInLayout(); requestLayout(); } @Override public void setSelection(int position) { } private void addAndMeasureChild(final View child, int viewPos) { LayoutParams params = child.getLayoutParams(); if (params == null) { params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); } addViewInLayout(child, viewPos, params, true); child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST), MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST)); } @Override protected synchronized void onLayout(boolean changed, int left, int top, int right, int bottom) { super.onLayout(changed, left, top, right, bottom); if (mAdapter == null) { return; } if (mDataChanged) { int oldCurrentX = mCurrentX; initView(); removeAllViewsInLayout(); mNextX = oldCurrentX; mDataChanged = false; } if (mScroller.computeScrollOffset()) { int scrollx = mScroller.getCurrX(); mNextX = scrollx; } if (mNextX <= 0) { mNextX = 0; mScroller.forceFinished(true); } if (mNextX >= mMaxX) { mNextX = mMaxX; mScroller.forceFinished(true); } int dx = mCurrentX - mNextX; removeNonVisibleItems(dx); fillList(dx); positionItems(dx); mCurrentX = mNextX; if (!mScroller.isFinished()) { post(new Runnable() { @Override public void run() { requestLayout(); } }); } } private void fillList(final int dx) { int edge = 0; View child = getChildAt(getChildCount() - 1); if (child != null) { edge = child.getRight(); } fillListRight(edge, dx); edge = 0; child = getChildAt(0); if (child != null) { edge = child.getLeft(); } fillListLeft(edge, dx); } private void fillListRight(int rightEdge, final int dx) { while (rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) { View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(), this); addAndMeasureChild(child, -1); rightEdge += child.getMeasuredWidth(); if (mRightViewIndex == mAdapter.getCount() - 1) { mMaxX = mCurrentX + rightEdge - getWidth(); } if (mMaxX < 0) { mMaxX = 0; } mRightViewIndex++; } } private void fillListLeft(int leftEdge, final int dx) { while (leftEdge + dx > 0 && mLeftViewIndex >= 0) { View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(), this); addAndMeasureChild(child, 0); leftEdge -= child.getMeasuredWidth(); mLeftViewIndex--; mDisplayOffset -= child.getMeasuredWidth(); } } private void removeNonVisibleItems(final int dx) { View child = getChildAt(0); while (child != null && child.getRight() + dx <= 0) { mDisplayOffset += child.getMeasuredWidth(); mRemovedViewQueue.offer(child); removeViewInLayout(child); mLeftViewIndex++; child = getChildAt(0); } child = getChildAt(getChildCount() - 1); while (child != null && child.getLeft() + dx >= getWidth()) { mRemovedViewQueue.offer(child); removeViewInLayout(child); mRightViewIndex--; child = getChildAt(getChildCount() - 1); } } private void positionItems(final int dx) { if (getChildCount() > 0) { mDisplayOffset += dx; int left = mDisplayOffset; for (int i = 0; i < getChildCount(); i++) { View child = getChildAt(i); int childWidth = child.getMeasuredWidth(); child.layout(left, 0, left + childWidth, child.getMeasuredHeight()); left += childWidth + child.getPaddingRight(); } } } public synchronized void scrollTo(int x) { mScroller.startScroll(mNextX, 0, x - mNextX, 0); requestLayout(); } /** * 上下滑动需要拦截, */ @Override public boolean dispatchTouchEvent(MotionEvent ev) { boolean handled = super.dispatchTouchEvent(ev); handled |= mGesture.onTouchEvent(ev); getParent().requestDisallowInterceptTouchEvent(true); switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: startX = (int) ev.getX(); startY = (int) ev.getY(); break; case MotionEvent.ACTION_MOVE: int endX = (int) ev.getX(); int endY = (int) ev.getY(); int dx = (int) (endX - startX); int dy = (int) (endY - startY); if (Math.abs(dx) + 50 > Math.abs(dy)) { } else { // 上下滑动,需要拦截 getParent().requestDisallowInterceptTouchEvent(false); } break; case MotionEvent.ACTION_UP: break; } return handled | super.dispatchTouchEvent(ev); } protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { synchronized (HorizontalListView.this) { mScroller.fling(mNextX, 0, (int) -velocityX, 0, 0, mMaxX, 0, 0); } requestLayout(); return true; } protected boolean onDown(MotionEvent e) { mScroller.forceFinished(true); return true; } private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() { @Override public boolean onDown(MotionEvent e) { return HorizontalListView.this.onDown(e); } @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { return HorizontalListView.this.onFling(e1, e2, velocityX, velocityY); } @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { synchronized (HorizontalListView.this) { mNextX += (int) distanceX; } requestLayout(); return true; } @Override public boolean onSingleTapConfirmed(MotionEvent e) { for (int i = 0; i < getChildCount(); i++) { View child = getChildAt(i); if (isEventWithinView(e, child)) { if (mOnItemClicked != null) { mOnItemClicked.onItemClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i)); } if (mOnItemSelected != null) { mOnItemSelected.onItemSelected(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i)); } break; } } return true; } @Override public void onLongPress(MotionEvent e) { int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { View child = getChildAt(i); if (isEventWithinView(e, child)) { if (mOnItemLongClicked != null) { mOnItemLongClicked.onItemLongClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i)); } break; } } } private boolean isEventWithinView(MotionEvent e, View child) { Rect viewRect = new Rect(); int[] childPosition = new int[2]; child.getLocationOnScreen(childPosition); int left = childPosition[0]; int right = left + child.getWidth(); int top = childPosition[1]; int bottom = top + child.getHeight(); viewRect.set(left, top, right, bottom); return viewRect.contains((int) e.getRawX(), (int) e.getRawY()); } }; //解决滑动和点击冲突问题 @Override public boolean onInterceptTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: startX = ev.getX(); startY = ev.getY(); break; case MotionEvent.ACTION_MOVE: float endX = ev.getX(); float endY = ev.getY(); float dx = endX - startX; float dy = endY - startY; if (Math.abs(dx) - 10 > Math.abs(dy)) { return true; } else if (Math.abs(dx) < Math.abs(dy) - 10) { return true; } break; case MotionEvent.ACTION_UP: break; } return super.onInterceptTouchEvent(ev); } }
在项目中的应用:
1.在xml布局文件中直接使用;
<com.wy.test.other.HorizontalListView android:id="@+id/hlv" android:layout_width="match_parent" android:layout_height="35dp" android:orientation="horizontal" />
2.填充数据(跟普通的listview一样);
// 获取屏幕宽高 int screenWidth = getWindowManager().getDefaultDisplay().getWidth(); // 屏幕宽(像素,如:480px) final String[] strings = new String[]{"零售", "零退", "批销", "批退", "调剂"}; HorizontalListViewAdapter horizontalListViewAdapter = new HorizontalListViewAdapter(getApplicationContext(), screenWidth, strings); hlv.setAdapter(horizontalListViewAdapter); hlv.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { ToastUtil.makeText(getApplicationContext(),strings[position]); } });2.1.adapter的代码
public class HorizontalListViewAdapter extends BaseAdapter { private final Context context; private final int screenWidth; private final String[] strings; public HorizontalListViewAdapter(Context applicationContext, int screenWidth, String[] strings) { this.context = applicationContext; this.screenWidth = screenWidth; this.strings = strings; } @Override public int getCount() { return strings.length; } @Override public Object getItem(int position) { return strings[position]; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder holder; if (convertView == null) { convertView = View.inflate(getApplicationContext(), R.layout.item_horizontallistview, null); holder = new ViewHolder(convertView); convertView.setTag(holder); }else { holder = (ViewHolder) convertView.getTag(); } //计算每条的宽度 ViewGroup.LayoutParams layoutParams = holder.rl.getLayoutParams(); layoutParams.width = screenWidth / 7 * 2; holder.rl.setLayoutParams(layoutParams); holder.tv.setText(strings[position]); return convertView; } } static class ViewHolder { @InjectView(R.id.tv) TextView tv; @InjectView(R.id.rl) RelativeLayout rl; ViewHolder(View view) { ButterKnife.inject(this, view); } }