listview的上拉加载更多和下拉刷新

<pre name="code" class="java"><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 1.1em; color: rgb(51, 51, 51); font-family: 'microsoft yahei'; font-size: 14px; line-height: 26px;">自己对研究这些控件蛮有兴趣的，我经常没事的时候就打开app来看，然后想它的这些功能是怎么实现的。。。然后我看到了一个下拉刷新和上拉加载的东西，，我就不断拿到来刷新刷新。。。然后通过查一些资料和我一直拖动刷新的经验。。。终于让我写了一个简单的下拉刷新和上拉加载的，还有一点小bug由于时间问题我就没有做修改，不过基本思路也是对的，我先记着以后自己要用的时候拿来修改一下就好。。 <br style="box-sizing: border-box;" />主要有这么几个要点： <br style="box-sizing: border-box;" />1、自定义listview的顶部，这个就是下拉刷新的时候拉下来的顶部布局，在一开始的时候需要将他隐藏，因此，首先通过measure方法测量出子view所占的空间，然后根据这个大小，拿到子view的高度，最后将子view的paddingtop设置为这个高度的负值，这样这个顶部的子view就会被隐藏起来并且可以在拖动的时候一点点的呈现出来。 <br style="box-sizing: border-box;" />2、需要拿到当前listview的状态。必须是当前listview滑倒了顶部才需要去拖出顶部布局，所以我们需要一个布尔值类型的变量作为判断是否在顶部。 <br style="box-sizing: border-box;" />3、需要当前手指的滚动状态，需要在2的基础根据当前的滚动状态是往上拖动的才会去触发listview的顶部拖拽下来的事件 <br style="box-sizing: border-box;" />4、需要根据滚动的状态，包括正常状态，拖拽状态，拖拽到一定程度释放就可以刷新的状态，正在刷新的状态。所以需要根据ontouch事件得到拖动的起始位置以及当前的位置，当达到相应的状态值的时候改变状态并且更新顶部布局 <br style="box-sizing: border-box;" />5、最大的重点就是ontouch事件，需要判断当前的触摸的位置，根据触摸的位置不断的更新顶部布局的paddingtop，让顶部布局可以一点一点呗拖拽下来。并且要根据4中说的不同的状态更新顶部布局 <br style="box-sizing: border-box;" />6、最后就是设定回调接口，供用户在main中完成数据的更新</p><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 1.1em; color: rgb(51, 51, 51); font-family: 'microsoft yahei'; font-size: 14px; line-height: 26px;">其实上拉加载的思路也差不多，反而对应的状态更少，其实也就是多一个回调接口。 <br style="box-sizing: border-box;" />不多说了，贴下代码</p>

package com.example.mylistview;import java.security.PublicKey;import android.content.Context;import android.gesture.GestureOverlayView;import android.os.AsyncTask;import android.util.AttributeSet;import android.util.Log;import android.view.GestureDetector.OnGestureListener;import android.view.LayoutInflater;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.widget.AbsListView;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.TextView;import android.widget.Toast;import android.widget.AbsListView.OnScrollListener;public class RereshListview extends ListView implements OnScrollListener{View head;View footer;int headHeight;//顶部布局文件的高度int footerHeight;//底部布局的高度int firstVisiable;//第一个可见的item项的位置int lastVisibale;//最后一个可见的item的位置int totolCount ;//定义一共有多少item项boolean isFirst = false;//判断是否是在listview的最顶端boolean isLast = false;//判断是否处在listview的底部int startY;//记录手指按下时候的位置int state;int scollState;private final int NONE = 0;//正常情况private final int PULL = 1;//向下拉的状态private final int RELESE = 2;//在向下拉伸到一定程度显示可以刷新时候的状态private final int REFRESHING = 3;//在达到刷新条件的时候释放了的状态private final int UP = 4;//向上拖拽的时候的状态private final int LOADING = 5;//拖拽完成之后释放要显示加载更多时候的状态onRefreshListener listener;public RereshListview(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initView(context);}public RereshListview(Context context, AttributeSet attrs) {super(context, attrs);initView(context);}public RereshListview(Context context) {super(context);initView(context);}public void initView(Context context){LayoutInflater inflater = LayoutInflater.from(context);head = inflater.inflate(R.layout.head_layout, null);footer = inflater.inflate(R.layout.foot_layout, null);measureView(head);//通知父布局head占用的空间大小，才能获取head布局的高度,android就是这么傻逼measureView(footer);headHeight = head.getMeasuredHeight();footerHeight = footer.getMeasuredHeight();System.out.println(footerHeight);System.out.println(headHeight);setTopPadding(-headHeight);setButtomPadding(-footerHeight);this.setOnScrollListener(this);this.addHeaderView(head);this.addFooterView(footer);}/** * 设置head布局的上边距 * @param top */private void setTopPadding(int top){head.setPadding(head.getPaddingLeft(), top,head.getPaddingRight(), head.getPaddingBottom());}/** * 设置底部footer布局的下边距，以实现隐藏和出现初始设置成高度负数 * @param buttom */private void setButtomPadding(int buttom){footer.setPadding(footer.getPaddingLeft(), footer.getPaddingTop(),footer.getPaddingRight(), buttom);}/** * 通知父布局head或者是footer的占用的空间大小 * @param view */private void measureView(View view){ViewGroup.LayoutParams lp = view.getLayoutParams();if (lp==null) {lp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);}int wide = ViewGroup.getChildMeasureSpec(0, 0, lp.width);int height;int tempHeight = lp.height;if (tempHeight>0) {height = MeasureSpec.makeMeasureSpec(tempHeight, MeasureSpec.EXACTLY);}else {height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);}view.measure(wide, height);}/** * 通知父级容器底部布局footer占用的位置大小 * @param view */public void mesuanFooterView(View view){ViewGroup.LayoutParams lp = view.getLayoutParams();if (lp == null) {lp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);}int wide = lp.width;int height;int tempheight = lp.height;if (tempheight>0) {height = MeasureSpec.makeMeasureSpec(tempheight, MeasureSpec.EXACTLY);}else {height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);}view.measure(wide, height);}/** * 滚动监听的事件 */@Overridepublic void onScrollStateChanged(AbsListView view, int scrollState) {this.scollState = scrollState;}@Overridepublic void onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) {this.firstVisiable = firstVisibleItem;this.lastVisibale = visibleItemCount+firstVisibleItem-1;this.totolCount = totalItemCount;}@Overridepublic boolean onTouchEvent(MotionEvent ev) {switch (ev.getAction()) {case MotionEvent.ACTION_DOWN:if (firstVisiable==0) {isFirst = true;startY = (int) ev.getY();}else if (lastVisibale == totolCount-1) {isLast = true;}break;case MotionEvent.ACTION_MOVE:onPullMove(ev);onUpMove(ev);break;case MotionEvent.ACTION_UP:if (state==RELESE) {state = REFRESHING;setTopPadding(0);listener.onPullRefresh();//设置上拉刷新的监听接口回调changeViewByState();//加载数据}else if (state==PULL) {state = NONE;}break;}return super.onTouchEvent(ev);}/** * 判断向下刷新的移动过程中需要执行的操作 * @param ev：当前触摸事件的参数 */public void onPullMove(MotionEvent ev){if (!isFirst) {return;}int tempY = (int) ev.getY();//当前手指移动的位置int space = (tempY - startY)/3;//移动了的距离int topPadding = space-headHeight;//根据当前移动距离和header的高度设置上边距switch (state) {case NONE:if (space>0) {state = PULL;setTopPadding(topPadding);changeViewByState();}break;case PULL:setTopPadding(topPadding);Log.e("height", "top"+topPadding+"heighr = "+headHeight);if (space>headHeight+30&&scollState==SCROLL_STATE_TOUCH_SCROLL) {state = RELESE;changeViewByState();}break;case RELESE:setTopPadding(topPadding);if (space<headHeight+30) {state = PULL;changeViewByState();}else if (space<0){//恢复初始状态state = NONE;isFirst = false;changeViewByState();}break;case REFRESHING:changeViewByState();break;}}/** * 在向上拖动时候的移动 * @param ev */public void onUpMove(MotionEvent ev){int space;if (!isLast) {return;}int tempY = (int) ev.getY();space = startY - tempY;int butttomPadding = footerHeight - space;switch (state) {case NONE:if (space>0) {//说明当前是向上拖动state = UP;//将当前状态修改为向上拖动Toast.makeText(getContext(), "up"+space, Toast.LENGTH_SHORT).show();changeViewByState();setButtomPadding(space);}break;case UP:if (space>30&&scollState == SCROLL_STATE_FLING) {state = LOADING;setButtomPadding(space);changeViewByState();}case LOADING:changeViewByState();setButtomPadding(space);listener.onUpResfresh();break;}}/** * 根据相应的当前状态改变head和footer的布局 */private void changeViewByState(){TextView tvTip = (TextView) head.findViewById(R.id.tip);ProgressBar progressBar = (ProgressBar) head.findViewById(R.id.progress_bar);TextView tipforload = (TextView) footer.findViewById(R.id.tv_tips);ProgressBar p = (ProgressBar) footer.findViewById(R.id.progressBar1);switch (state) {case NONE:setTopPadding(-headHeight);break;case PULL:tvTip.setText("下拉刷新");break;case RELESE:tvTip.setText("松开可以刷新");break;case REFRESHING:setTopPadding(0);tvTip.setText("正在刷新...");progressBar.setVisibility(VISIBLE);break;case UP:tipforload.setText("拖动加载更多");break;case LOADING:tipforload.setText("正在加载");p.setVisibility(VISIBLE);break;}}/** * 设置刷新事件监听器 * @param listener */public void setOnRefreshListener(onRefreshListener listener){this.listener = listener;}/** * 设置刷新完成后的状态 */public void onRefreshComplete(){TextView tView = (TextView) head.findViewById(R.id.tip);tView.setText("刷新完成");ProgressBar progressBar = (ProgressBar) head.findViewById(R.id.progress_bar);progressBar.setVisibility(GONE);new AsyncTask<Void, Void, Void>() {@Overrideprotected Void doInBackground(Void... params) {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}return null;}protected void onPostExecute(Void result) {state = NONE;isFirst = false;animationforComplete();invalidate();};}.execute();}/** * 当上拉操作完成时候执行的操作 */public void onUpComplete(){state = NONE;isLast = false;setButtomPadding(-footerHeight);}/** * 在完成刷新之后回到原先正常布局时候的过度动画 */private void animationforComplete(){new AsyncTask<Void, Void, Void>(){int i = 0;@Overrideprotected Void doInBackground(Void... params) {while(i>=-headHeight){i--;try {Thread.sleep(3);publishProgress();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}return null;}protected void onProgressUpdate(Void[] values) {setTopPadding(i);};}.execute();}/** * 刷新事件接口 * @author Chenhp * */public interface onRefreshListener{void onPullRefresh();void onUpResfresh();}}