編輯:關於Android編程
分享一個下拉刷新的解決辦法,效果圖:
Main.java:
package example.com.list; import java.util.LinkedList; import example.com.list.R; import example.com.list.R.id; import example.com.list.R.layout; import example.com.list.MyListView.OnRefreshListener; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; public class MainActivity extends Activity { private LinkedListListView.java:data; private BaseAdapter adapter; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); data = new LinkedList (); for(int i=0;i<6;i++){ data.add(String.valueOf(i)); } final MyListView listView = (MyListView) findViewById(R.id.listView); adapter = new BaseAdapter() { public View getView(int position, View convertView, ViewGroup parent) { convertView=LayoutInflater.from(getApplicationContext()).inflate(R.layout.item, null); TextView textView = (TextView) convertView.findViewById(R.id.textView_item); textView.setText(data.get(position)); return convertView; } public long getItemId(int position) { return position; } public Object getItem(int position) { return data.get(position); } public int getCount() { return data.size(); } }; listView.setAdapter(adapter); listView.setonRefreshListener(new OnRefreshListener() { public void onRefresh() { new AsyncTask () { protected Void doInBackground(Void... params) { try { Thread.sleep(1000); } catch (Exception e) { e.printStackTrace(); } return null; } @Override protected void onPostExecute(Void result) { adapter.notifyDataSetChanged(); listView.onRefreshComplete(); } }; } }); } }
package example.com.list; import java.text.SimpleDateFormat; import java.util.Date; import example.com.list.R; import example.com.list.R.drawable; import example.com.list.R.id; import example.com.list.R.layout; import android.content.Context; import android.util.AttributeSet; import android.util.Log; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.animation.LinearInterpolator; import android.view.animation.RotateAnimation; import android.widget.AbsListView; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.AbsListView.OnScrollListener; import android.widget.ProgressBar; import android.widget.TextView; public class MyListView extends ListView implements OnScrollListener { private static final String TAG = listview; private final static int RELEASE_To_REFRESH = 0; //釋放刷新 private final static int PULL_To_REFRESH = 1;//拉動刷新 private final static int REFRESHING = 2;//正在刷新 private final static int DONE = 3; private final static int LOADING = 4; // 實際的padding的距離與界面上偏移距離的比例 private final static int RATIO = 3; private LayoutInflater inflater; private LinearLayout headView; private TextView tipsTextview; private TextView lastUpdatedTextView; private ImageView arrowImageView; private ProgressBar progressBar; private RotateAnimation animation; private RotateAnimation reverseAnimation; // 用於保證startY的值在一個完整的touch事件中只被記錄一次 private boolean isRecored; private int headContentWidth; private int headContentHeight; private int startY; private int firstItemIndex; private int state; private boolean isBack; private OnRefreshListener refreshListener; private boolean isRefreshable; public MyListView(Context context) { super(context); init(context); } public MyListView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } private void init(Context context) { //setCacheColorHint(context.getResources().getColor(R.color.transparent)); inflater = LayoutInflater.from(context); headView = (LinearLayout) inflater.inflate(R.layout.head, null); arrowImageView = (ImageView) headView .findViewById(R.id.head_arrowImageView); arrowImageView.setMinimumWidth(70); arrowImageView.setMinimumHeight(50); progressBar = (ProgressBar) headView .findViewById(R.id.head_progressBar); tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView); lastUpdatedTextView = (TextView) headView .findViewById(R.id.head_lastUpdatedTextView); measureView(headView); headContentHeight = headView.getMeasuredHeight(); headContentWidth = headView.getMeasuredWidth(); headView.setPadding(0, -1 * headContentHeight, 0, 0); headView.invalidate(); addHeaderView(headView, null, false); setOnScrollListener(this); animation = new RotateAnimation(0, -180, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); animation.setInterpolator(new LinearInterpolator()); animation.setDuration(250); animation.setFillAfter(true); reverseAnimation = new RotateAnimation(-180, 0, RotateAnimation.RELATIVE_TO_SELF, 0.5f, RotateAnimation.RELATIVE_TO_SELF, 0.5f); reverseAnimation.setInterpolator(new LinearInterpolator()); reverseAnimation.setDuration(200); reverseAnimation.setFillAfter(true); state = DONE; isRefreshable = false; } public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2, int arg3) { firstItemIndex = firstVisiableItem; } public void onScrollStateChanged(AbsListView arg0, int arg1) { } public boolean onTouchEvent(MotionEvent event) { if (isRefreshable) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: if (firstItemIndex == 0 && !isRecored) { isRecored = true; startY = (int) event.getY(); } break; case MotionEvent.ACTION_UP: if (state != REFRESHING && state != LOADING) { if (state == DONE) { } if (state == PULL_To_REFRESH) { state = DONE; changeHeaderViewByState(); } if (state == RELEASE_To_REFRESH) { state = REFRESHING; changeHeaderViewByState(); onRefresh(); } } isRecored = false; isBack = false; break; case MotionEvent.ACTION_MOVE: int tempY = (int) event.getY(); if (!isRecored && firstItemIndex == 0) { isRecored = true; startY = tempY; } if (state != REFRESHING && isRecored && state != LOADING) { // 保證在設置padding的過程中,當前的位置一直是在head,否則如果當列表超出屏幕的話,當在上推的時候,列表會同時進行滾動 // 可以松手去刷新了 if (state == RELEASE_To_REFRESH) { setSelection(0); // 往上推了,推到了屏幕足夠掩蓋head的程度,但是還沒有推到全部掩蓋的地步 if (((tempY - startY) / RATIO < headContentHeight) && (tempY - startY) > 0) { state = PULL_To_REFRESH; changeHeaderViewByState(); } // 一下子推到頂了 else if (tempY - startY <= 0) { state = DONE; changeHeaderViewByState(); } // 往下拉了,或者還沒有上推到屏幕頂部掩蓋head的地步 else { // 不用進行特別的操作,只用更新paddingTop的值就行了 } } // 還沒有到達顯示松開刷新的時候,DONE或者是PULL_To_REFRESH狀態 if (state == PULL_To_REFRESH) { setSelection(0); // 下拉到可以進入RELEASE_TO_REFRESH的狀態 if ((tempY - startY) / RATIO >= headContentHeight) { state = RELEASE_To_REFRESH; isBack = true; changeHeaderViewByState(); } // 上推到頂了 else if (tempY - startY <= 0) { state = DONE; changeHeaderViewByState(); } } // done狀態下 if (state == DONE) { if (tempY - startY > 0) { state = PULL_To_REFRESH; changeHeaderViewByState(); } } // 更新headView的size if (state == PULL_To_REFRESH) { headView.setPadding(0, -1 * headContentHeight + (tempY - startY) / RATIO, 0, 0); } // 更新headView的paddingTop if (state == RELEASE_To_REFRESH) { headView.setPadding(0, (tempY - startY) / RATIO - headContentHeight, 0, 0); } } break; } } return super.onTouchEvent(event); } // 當狀態改變時候,調用該方法,以更新界面 private void changeHeaderViewByState() { switch (state) { case RELEASE_To_REFRESH: arrowImageView.setVisibility(View.VISIBLE); progressBar.setVisibility(View.GONE); tipsTextview.setVisibility(View.VISIBLE); lastUpdatedTextView.setVisibility(View.VISIBLE); arrowImageView.clearAnimation(); arrowImageView.startAnimation(animation); tipsTextview.setText(Release); break; case PULL_To_REFRESH: progressBar.setVisibility(View.GONE); tipsTextview.setVisibility(View.VISIBLE); lastUpdatedTextView.setVisibility(View.VISIBLE); arrowImageView.clearAnimation(); arrowImageView.setVisibility(View.VISIBLE); // 是由RELEASE_To_REFRESH狀態轉變來的 if (isBack) { isBack = false; arrowImageView.clearAnimation(); arrowImageView.startAnimation(reverseAnimation); tipsTextview.setText(Pull down); } else { tipsTextview.setText(Pull down); } break; case REFRESHING: headView.setPadding(0, 0, 0, 0); progressBar.setVisibility(View.VISIBLE); arrowImageView.clearAnimation(); arrowImageView.setVisibility(View.GONE); tipsTextview.setText(Refreshing...); lastUpdatedTextView.setVisibility(View.VISIBLE); break; case DONE: headView.setPadding(0, -1 * headContentHeight, 0, 0); progressBar.setVisibility(View.GONE); arrowImageView.clearAnimation(); arrowImageView.setImageResource(R.drawable.arrow_down); tipsTextview.setText(Pull down); lastUpdatedTextView.setVisibility(View.VISIBLE); break; } } public void setonRefreshListener(OnRefreshListener refreshListener) { this.refreshListener = refreshListener; isRefreshable = true; } public interface OnRefreshListener { public void onRefresh(); } public void onRefreshComplete() { state = DONE; SimpleDateFormat format=new SimpleDateFormat(yyyy.MM.dd. HH:mm); String date=format.format(new Date()); lastUpdatedTextView.setText(recently: + date); changeHeaderViewByState(); } private void onRefresh() { if (refreshListener != null) { refreshListener.onRefresh(); } } private void measureView(View child) { ViewGroup.LayoutParams p = child.getLayoutParams(); if (p == null) { p = new ViewGroup.LayoutParams( ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width); int lpHeight = p.height; int childHeightSpec; if (lpHeight > 0) { childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY); } else { childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); } child.measure(childWidthSpec, childHeightSpec); } public void setAdapter(BaseAdapter adapter) { SimpleDateFormat format=new SimpleDateFormat(yyyy.MM.dd. HH:mm); String date=format.format(new Date()); lastUpdatedTextView.setText(recently: + date); super.setAdapter(adapter); } }
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