ListView下拉加载

1、MyListView.java

public class MyListView extends ListView implements OnScrollListener {private final static int RELEASE_To_REFRESH = 0;// 下拉过程的状态值private final static int PULL_To_REFRESH = 1; // 从下拉返回到不刷新的状态值private final static int REFRESHING = 2;// 正在刷新的状态值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;// ListView头部下拉刷新的布局private LinearLayout headerView;private TextView lvHeaderTipsTv;private TextView lvHeaderLastUpdatedTv;private ImageView lvHeaderArrowIv;private ProgressBar lvHeaderProgressBar;// 定义头部下拉刷新的布局的高度private int headerContentHeight;private RotateAnimation animation;private RotateAnimation reverseAnimation;private int startY;private int state;private boolean isBack;// 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 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) {inflater = LayoutInflater.from(context);headerView = (LinearLayout) inflater.inflate(R.layout.lv_header, null);lvHeaderTipsTv = (TextView) headerView.findViewById(R.id.lvHeaderTipsTv);lvHeaderLastUpdatedTv = (TextView) headerView.findViewById(R.id.lvHeaderLastUpdatedTv);lvHeaderArrowIv = (ImageView) headerView.findViewById(R.id.lvHeaderArrowIv);// 设置下拉刷新图标的最小高度和宽度lvHeaderArrowIv.setMinimumWidth(70);lvHeaderArrowIv.setMinimumHeight(50);lvHeaderProgressBar = (ProgressBar) headerView.findViewById(R.id.lvHeaderProgressBar);measureView(headerView);headerContentHeight = headerView.getMeasuredHeight();// 设置内边距，正好距离顶部为一个负的整个布局的高度，正好把头部隐藏headerView.setPadding(0, -1 * headerContentHeight, 0, 0);// 重绘一下headerView.invalidate();// 将下拉刷新的布局加入ListView的顶部addHeaderView(headerView, null, false);// 设置滚动监听事件setOnScrollListener(this);// 设置旋转动画事件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);// 一开始的状态就是下拉刷新完的状态，所以为DONEstate = DONE;// 是否正在刷新isRefreshable = false;}@Overridepublic void onScrollStateChanged(AbsListView view, int scrollState) {}@Overridepublic void onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) {if (firstVisibleItem == 0) {isRefreshable = true;} else {isRefreshable = false;}}@Overridepublic boolean onTouchEvent(MotionEvent ev) {if (isRefreshable) {switch (ev.getAction()) {case MotionEvent.ACTION_DOWN:if (!isRecored) {isRecored = true;startY = (int) ev.getY();// 手指按下时记录当前位置}break;case MotionEvent.ACTION_UP:if (state != REFRESHING && state != LOADING) {if (state == PULL_To_REFRESH) {state = DONE;changeHeaderViewByState();}if (state == RELEASE_To_REFRESH) {state = REFRESHING;changeHeaderViewByState();onLvRefresh();}}isRecored = false;isBack = false;break;case MotionEvent.ACTION_MOVE:int tempY = (int) ev.getY();if (!isRecored) {isRecored = true;startY = tempY;}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 < headerContentHeight)// 由松开刷新状态转变到下拉刷新状态&& (tempY - startY) > 0) {state = PULL_To_REFRESH;changeHeaderViewByState();}// 一下子推到顶了else if (tempY - startY <= 0) {// 由松开刷新状态转变到done状态state = DONE;changeHeaderViewByState();}}// 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if ((tempY - startY) / RATIO >= headerContentHeight) {// 由done或者下拉刷新状态转变到松开刷新state = RELEASE_To_REFRESH;isBack = true;changeHeaderViewByState();}// 上推到顶了else if (tempY - startY <= 0) {// 由DOne或者下拉刷新状态转变到done状态state = DONE;changeHeaderViewByState();}}// done状态下if (state == DONE) {if (tempY - startY > 0) {state = PULL_To_REFRESH;changeHeaderViewByState();}}// 更新headView的sizeif (state == PULL_To_REFRESH) {headerView.setPadding(0, -1 * headerContentHeight+ (tempY - startY) / RATIO, 0, 0);}// 更新headView的paddingTopif (state == RELEASE_To_REFRESH) {headerView.setPadding(0, (tempY - startY) / RATIO- headerContentHeight, 0, 0);}}break;default:break;}}return super.onTouchEvent(ev);}// 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:lvHeaderArrowIv.setVisibility(View.VISIBLE);lvHeaderProgressBar.setVisibility(View.GONE);lvHeaderTipsTv.setVisibility(View.VISIBLE);lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);lvHeaderArrowIv.clearAnimation();// 清除动画lvHeaderArrowIv.startAnimation(animation);// 开始动画效果lvHeaderTipsTv.setText("松开刷新");break;case PULL_To_REFRESH:lvHeaderProgressBar.setVisibility(View.GONE);lvHeaderTipsTv.setVisibility(View.VISIBLE);lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);lvHeaderArrowIv.clearAnimation();lvHeaderArrowIv.setVisibility(View.VISIBLE);// 是由RELEASE_To_REFRESH状态转变来的if (isBack) {isBack = false;lvHeaderArrowIv.clearAnimation();lvHeaderArrowIv.startAnimation(reverseAnimation);lvHeaderTipsTv.setText("下拉刷新");} else {lvHeaderTipsTv.setText("下拉刷新");}break;case REFRESHING:headerView.setPadding(0, 0, 0, 0);lvHeaderProgressBar.setVisibility(View.VISIBLE);lvHeaderArrowIv.clearAnimation();lvHeaderArrowIv.setVisibility(View.GONE);lvHeaderTipsTv.setText("正在刷新...");lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);break;case DONE:headerView.setPadding(0, -1 * headerContentHeight, 0, 0);lvHeaderProgressBar.setVisibility(View.GONE);lvHeaderArrowIv.clearAnimation();lvHeaderArrowIv.setImageResource(R.drawable.arrow);lvHeaderTipsTv.setText("下拉刷新");lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);break;}}// 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heightprivate void measureView(View child) {ViewGroup.LayoutParams params = child.getLayoutParams();if (params == null) {params = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);}int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0,params.width);int lpHeight = params.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 setonRefreshListener(OnRefreshListener refreshListener) {this.refreshListener = refreshListener;isRefreshable = true;}public interface OnRefreshListener {public void onRefresh();}public void onRefreshComplete() {state = DONE;lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString());changeHeaderViewByState();}private void onLvRefresh() {if (refreshListener != null) {refreshListener.onRefresh();}}public void setAdapter(LvAdapter adapter) {lvHeaderLastUpdatedTv.setText("最近更新:" + new Date().toLocaleString());super.setAdapter(adapter);}}

2、MainActivity.java

public class MainActivity extends Activity {private List<String> list;private MyListView lv;private LvAdapter adapter;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);lv = (MyListView) findViewById(R.id.lv);list = new ArrayList<String>();list.add("loonggg");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");list.add("我们都是开发者");adapter = new LvAdapter(list, this);lv.setAdapter(adapter);lv.setonRefreshListener(new OnRefreshListener() {@Overridepublic void onRefresh() {new AsyncTask<Void, Void, Void>() {protected Void doInBackground(Void... params) {try {Thread.sleep(1000);} catch (Exception e) {e.printStackTrace();}list.add("刷新后添加的内容");return null;}@Overrideprotected void onPostExecute(Void result) {adapter.notifyDataSetChanged();lv.onRefreshComplete();}}.execute(null, null, null);}});}}

3、LvAdapter

public class LvAdapter extends BaseAdapter {private List<String> list;private Context context;public LvAdapter(List<String> list, Context context) {this.list = list;this.context = context;}@Overridepublic int getCount() {return list.size();}@Overridepublic Object getItem(int position) {return list.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {TextView tv = new TextView(context.getApplicationContext());tv.setText(list.get(position));return tv;}}

4、lv_header.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:background="#000000" >    <!-- 内容 -->    <RelativeLayout        android:id="@+id/head_contentLayout"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        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:id="@+id/lvHeaderArrowIv"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_gravity="center"                android:src="@drawable/arrow" />            <!-- 进度条 -->            <ProgressBar                android:id="@+id/lvHeaderProgressBar"                style="?android:attr/progressBarStyleSmall"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_gravity="center"                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:gravity="center_horizontal"            android:orientation="vertical" >            <!-- 提示 -->            <TextView                android:id="@+id/lvHeaderTipsTv"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="下拉刷新"                android:textColor="#fff"                android:textSize="20sp" />            <!-- 最近更新 -->            <TextView                android:id="@+id/lvHeaderLastUpdatedTv"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="上次更新"                android:textColor="#333"                android:textSize="10sp" />        </LinearLayout>    </RelativeLayout></LinearLayout>

5、main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="#000000"    android:orientation="vertical" >    <net.loonggg.listview.MyListView        android:id="@+id/lv"        android:layout_width="fill_parent"        android:layout_height="fill_parent" /></LinearLayout>