Android Listview下拉刷新数据
openkk
12年前
Android listview仿新浪微博下拉刷新例子，其实所有此功能最早是国外实现的，现在网上能看到的都是基于这个例子，只是有些细节不同。算法上确实比较巧妙，直得学习一下。
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="cn.com.karl.list" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="4" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:label="@string/app_name" android:name=".MainActivity" > <intent-filter > <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>main..xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <cn.com.karl.list.MyListView android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/listView" /> </LinearLayout>head.xml
<?xml version="1.0" encoding="utf-8"?> <!-- ListView的头部 --> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#ffffff" > <!-- 内容 --> <RelativeLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:id="@+id/head_contentLayout" android:paddingLeft="30dp" > <!-- 箭头图像、进度条 --> <FrameLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_centerVertical="true" > <!-- 箭头 --> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:src="@drawable/arrow_down" android:id="@+id/head_arrowImageView" /> <!-- 进度条 --> <ProgressBar android:layout_width="wrap_content" android:layout_height="wrap_content" style="?android:attr/progressBarStyleSmall" android:layout_gravity="center" android:id="@+id/head_progressBar" android:visibility="gone" /> </FrameLayout> <!-- 提示、最近更新 --> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:orientation="vertical" android:gravity="center_horizontal" > <!-- 提示 --> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下拉刷新" android:textSize="15dp" android:id="@+id/head_tipsTextView" /> <!-- 最近更新 --> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/head_lastUpdatedTextView" android:text="上次更新" android:textSize="12dp" /> </LinearLayout> </RelativeLayout> </LinearLayout>item.xml
<?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="wrap_content" android:gravity="center_vertical" android:background="#ffffff" android:orientation="horizontal" > <ImageView android:id="@+id/imageView_item" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="10dp" android:src="@drawable/ic_launcher" /> <TextView android:id="@+id/textView_item" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="10dp" android:text="TextView" /> </LinearLayout>MainActivity.java
package cn.com.karl.list; import java.util.LinkedList; import cn.com.karl.list.MyListView.OnRefreshListener; import android.app.Activity; import android.content.res.Configuration; import android.os.AsyncTask; import android.os.Bundle; import android.util.DisplayMetrics; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.WindowManager; import android.widget.BaseAdapter; import android.widget.TextView; public class MainActivity extends Activity { private LinkedList<String> data; private BaseAdapter adapter; private MyListView listView; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // 取得屏幕尺寸大小 displayScreenSize(); data = new LinkedList<String>(); for(int i=0;i<10;i++) { data.add(String.valueOf(i)); } 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() { RefreshTask rTask = new RefreshTask(); rTask.execute(1000); } }); } // AsyncTask异步任务 class RefreshTask extends AsyncTask<Integer, Integer, String> { @Override protected String doInBackground(Integer... params) { try { Thread.sleep(params[0]); } catch (Exception e) { e.printStackTrace(); } // 在data最前添加数据 data.addFirst("刷新后的内容"); return null; } @Override protected void onPostExecute(String result) { super.onPostExecute(result); adapter.notifyDataSetChanged(); listView.onRefreshComplete(); } } // 取得屏幕尺寸大小 public void displayScreenSize() { // 屏幕方面切换时获得方向 if (this.getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) { setTitle("landscape"); } if (this.getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) { setTitle("portrait"); } // 获得屏幕大小1 WindowManager manager = getWindowManager(); int width = manager.getDefaultDisplay().getWidth(); int height = manager.getDefaultDisplay().getHeight(); Log.v("am10", "width: " + width + " height: " + height); // 获得屏幕大小2 DisplayMetrics dMetrics = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(dMetrics); int screenWidth = dMetrics.widthPixels; int screenHeight = dMetrics.heightPixels; Log.v("am10", "screenWidth: " + screenWidth + " screenHeight: " + screenHeight); } } MyListView.java package cn.com.karl.list; import java.text.SimpleDateFormat; import java.util.Date; 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 = "am10"; private final static int RELEASE_To_REFRESH = 0; private final static int PULL_To_REFRESH = 1; private final static int REFRESHING = 2; private final static int DONE = 3; private final static int LOADING = 4; // 实际的padding的距离与界面上偏移距离的比例 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; // 用于保证startY的值在一个完整的touch事件中只被记录一次 private boolean isRecored; private int startY; private int firstItemIndex; private int headContentWidth; private int headContentHeight; 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); // 估算headView的宽和高 measureView(headView); headContentHeight = headView.getMeasuredHeight(); headContentWidth = headView.getMeasuredWidth(); headView.setPadding(0, -1 * headContentHeight, 0, 0); headView.invalidate(); Log.v(TAG, "width:" + headContentWidth + " height:" + headContentHeight); 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; //Log.v(TAG, "firstItemIndex: "+firstItemIndex); } public void onScrollStateChanged(AbsListView arg0, int arg1) { } public boolean onTouchEvent(MotionEvent event) { // Log.v(TAG, "isRefreshable: "+isRefreshable); if (isRefreshable) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: if (firstItemIndex == 0 && !isRecored) { isRecored = true; // 触摸屏幕的位置 startY = (int) event.getY(); Log.v(TAG, "在down时候记录当前位置" + " startY:"+startY); } break; case MotionEvent.ACTION_UP: if (state != REFRESHING && state != LOADING) { if (state == DONE) { // 什么都不做 } if (state == PULL_To_REFRESH) { state = DONE; changeHeaderViewByState(); Log.v(TAG, "由下拉刷新状态，到done状态"); } if (state == RELEASE_To_REFRESH) { state = REFRESHING; changeHeaderViewByState(); onRefresh(); Log.v(TAG, "由松开刷新状态，到done状态"); } } isRecored = false; isBack = false; break; case MotionEvent.ACTION_MOVE: int tempY = (int) event.getY(); //Log.v(TAG, "tempY: " + tempY); /** * 手指移动过程中tempY数据会不断变化,当滑动到firstItemIndex,即到达顶部, * 需要记录手指所在屏幕的位置: startY = tempY ,后面作位置比较使用 * * 如果手指继续向下推,tempY继续变化,当tempY-startY>0,即是需要显示header部分 * * 此时需要更改状态：state = PULL_To_REFRESH */ if (!isRecored && firstItemIndex == 0) { isRecored = true; startY = tempY; Log.v(TAG, "在move时候记录下位置" + " startY:"+startY); } if (state != REFRESHING && isRecored && state != LOADING) { /** * 保证在设置padding的过程中，当前的位置一直是在head， * 否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动 */ // 可以松手去刷新了 if (state == RELEASE_To_REFRESH) { setSelection(0); // 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步 if (((tempY - startY) / RATIO < headContentHeight) && (tempY - startY) > 0) { state = PULL_To_REFRESH; changeHeaderViewByState(); Log.v(TAG, "由松开刷新状态转变到下拉刷新状态"); } // 一下子推到顶了,没有显示header部分时,应该恢复DONE状态,这里机率很小 else if (tempY - startY <= 0) { state = DONE; changeHeaderViewByState(); Log.v(TAG, "---由松开刷新状态转变到done状态"); } else { // 往下拉了，或者还没有上推到屏幕顶部掩盖head的地步 // 不用进行特别的操作，只用更新paddingTop的值就行了 } } // 还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态 if (state == PULL_To_REFRESH) { setSelection(0); /** * 下拉到可以进入RELEASE_TO_REFRESH的状态 * * 等于headContentHeight时,即是正好完全显示header部分 * 大于headContentHeight时,即是超出header部分更多 * * 当header部分能够完全显示或者超出显示, * 需要更改状态: state = RELEASE_To_REFRESH */ if ((tempY - startY) / RATIO >= headContentHeight) { state = RELEASE_To_REFRESH; isBack = true; changeHeaderViewByState(); Log.v(TAG, "由done或者下拉刷新状态转变到松开刷新"); } // 上推到顶了,没有显示header部分时,应该恢复DONE状态 else if (tempY - startY <= 0) { state = DONE; changeHeaderViewByState(); Log.v(TAG, "由done或者下拉刷新状态转变到done状态"); } } // done状态下 if (state == DONE) { if (tempY - startY > 0) { /** * 手指移动过程中tempY数据会不断变化,当滑动到firstItemIndex,即到达顶部, * 需要记录手指所在屏幕的位置: startY = tempY ,后面作位置比较使用 * * 如果手指继续向下推,tempY继续变化,当tempY-startY>0,即是需要显示header部分 * * 此时需要更改状态：state = PULL_To_REFRESH */ //Log.v(TAG, "----------------PULL_To_REFRESH " + (tempY - startY)); state = PULL_To_REFRESH; changeHeaderViewByState(); } } // 更新headView的paddingTop if (state == PULL_To_REFRESH) { //Log.v(TAG, "----------------PULL_To_REFRESH2 " + (tempY - startY)); headView.setPadding(0, -1 * headContentHeight + (tempY - startY) / RATIO, 0, 0); } // 继续更新headView的paddingTop if (state == RELEASE_To_REFRESH) { headView.setPadding(0, (tempY - startY) / RATIO - headContentHeight, 0, 0); } } break; } } return super.onTouchEvent(event); } // 当状态改变时候，调用该方法，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("松开刷新"); Log.v(TAG, "当前状态，松开刷新"); break; case PULL_To_REFRESH: //progressBar.setVisibility(View.GONE); tipsTextview.setVisibility(View.VISIBLE); lastUpdatedTextView.setVisibility(View.VISIBLE); arrowImageView.clearAnimation(); arrowImageView.setVisibility(View.VISIBLE); /** * 是否向下滑回，是由RELEASE_To_REFRESH状态转变来的 */ if (isBack) { isBack = false; arrowImageView.clearAnimation(); arrowImageView.startAnimation(reverseAnimation); tipsTextview.setText("下拉刷新"); //Log.v(TAG, "isBack: " + isBack); } else { tipsTextview.setText("下拉刷新"); //Log.v(TAG, "isBack: " + isBack); } Log.v(TAG, "当前状态，下拉刷新"); break; case REFRESHING: Log.v(TAG, "REFRESHING..."); headView.setPadding(0, 0, 0, 0); //progressBar.setVisibility(View.VISIBLE); arrowImageView.clearAnimation(); arrowImageView.setVisibility(View.GONE); tipsTextview.setText("正在刷新..."); lastUpdatedTextView.setVisibility(View.VISIBLE); Log.v(TAG, "当前状态,正在刷新..."); break; case DONE: headView.setPadding(0, -1 * headContentHeight, 0, 0); //progressBar.setVisibility(View.GONE); arrowImageView.clearAnimation(); arrowImageView.setImageResource(R.drawable.arrow_down); tipsTextview.setText("下拉刷新"); lastUpdatedTextView.setVisibility(View.VISIBLE); Log.v(TAG, "当前状态，done"); 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年MM月dd日 HH:mm"); String date = format.format(new Date()); lastUpdatedTextView.setText("最近更新:" + date); changeHeaderViewByState(); } private void onRefresh() { if (refreshListener != null) { refreshListener.onRefresh(); } } // 此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”headView的width以及height private void measureView(View child) { ViewGroup.LayoutParams p = child.getLayoutParams(); if (p == null) { //Log.v(TAG, "LayoutParams is 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年MM月dd日 HH:mm"); String date=format.format(new Date()); lastUpdatedTextView.setText("最近更新:" + date); super.setAdapter(adapter); } } 这个例子忘记那里下载的，这里也尊重作者，注明并不是我本人写的。如果谁知道原作者资料请告知，在此添加。
我修改了一下代码，使用AsyncTask异步任务更新数据，还有添加和修改了一些注释。