弹性ScrollView下拉弹性显示底部内容的简单实现

今天写了ScrollView的下拉,弹性显示底部内容继续加载的例子,之所以不用ListView是因为ListView基本只能一列,不好实现瀑布流效果,而ScrollView基本没什么限制,所以就简单实现了一下ScrollView的相同效果,看了网上的很多相似的做法,写得确实很不错,不过看起来还是比较费劲的,本人新手,尽量就按照自己的理解,简易的实现了一下,东西内容不多,就显示和隐藏的一般逻辑,没有太多界面上复杂的东西首先,个人实现的原理,原理也很简单,就是重写ScrollView的OnTouchEvent方法来实现对ScrollView,触屏事件的监听把"继续加载"的View放在下方,设置BottomPadding为负的View高度,所以一开始就不显示了当滚动到ScrollView的子View显示完后,再不断的设置"继续加载View"的BottomPadding,于是"继续加载View"就能不断显示了,将该VIew不断隐藏也是同样的原理。主要的实现类

public class LaScrollView extends ScrollView implements ShowHide {LinearLayout llController, llRefresh;LinearLayout llContent;// llContent是否滚到底boolean isBottom;int svHeight;int llControllerHeight;int llRefreshHeight;TextView tvView;LaScrollView sv = this;// 是否可以进行加载boolean continueLoad = false;public void init() {measureView(llController);measureView(llRefresh);llControllerHeight = llController.getMeasuredHeight();llRefreshHeight = llRefresh.getMeasuredHeight();showHide(0, false);}public LaScrollView(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stub}// 估计/计算View的高度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, 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);}float y;public boolean onTouchEvent(MotionEvent event) {float curY = event.getY();float moveY; // 等于 curY - y; 负数表示手指向上 ,正数表示手指向下switch (event.getAction()) {case MotionEvent.ACTION_DOWN:y = curY;break;case MotionEvent.ACTION_MOVE:moveY = curY - y;Log.v("moveY ", "" + moveY);if (moveY < 0) {// 向上滑动,有可能要显示隐藏的VIewif (sv.getHeight() + sv.getScrollY() == llController.getHeight()) {isBottom = true;}}if (isBottom) { // llContent滚到底端if (moveY > 0) { // 慢慢隐藏showHide((int) (-moveY - 1), true);} else {// 有可能会拉出隐藏ViewshowHide((int) (-moveY), true);}}y = curY;break;case MotionEvent.ACTION_UP:y = curY;if (continueLoad) {// 可以加载状态下松手TextView child = new TextView(getContext());showHide(0, false);child.setText("我是新来的");llContent.addView(child);continueLoad = false;} else {showHide(0, false);}tvView.setText("向上拖动进行加载");break;}return super.onTouchEvent(event);};@Overridepublic void showHide(int move, boolean isShow) {// TODO Auto-generated method stubif (isShow) {llRefresh.setVisibility(View.VISIBLE);int olePadding = llRefresh.getPaddingBottom();int newPadding = olePadding + move;Log.v("new Padding ", " move " + move + "  \n" + newPadding);if (move > 0) {// 不断显示if (newPadding > 0) {llRefresh.setPadding(0, 0, 0, 0);} else {if (((float) (llRefreshHeight + newPadding))/ llRefreshHeight > 0.9) {// 设置什么时候可以刷新条件自己定tvView.setText("放手继续加载");continueLoad = true;}llRefresh.setPadding(0, 0, 0, newPadding);}} else {// 不停隐藏int neHeight = -llRefreshHeight;if (newPadding < neHeight) {llRefresh.setPadding(0, 0, 0, neHeight);isBottom = false;} else {if (((float) (llRefreshHeight + newPadding))/ llRefreshHeight < 0.9) {// 设置什么时候可以刷新条件自己定tvView.setText("向上拖动进行加载");continueLoad = false;}llRefresh.setPadding(0, 0, 0, newPadding);}}} else {llRefresh.setPadding(0, 0, 0, -llRefreshHeight);}}public void setLlController(LinearLayout llController) {this.llController = llController;}public void setLlContent(LinearLayout llContent) {this.llContent = llContent;}public void setLlRefresh(LinearLayout llRefresh) {this.llRefresh = llRefresh;}public void setTvView(TextView tvView) {this.tvView = tvView;}}interface ShowHide {public void showHide(int move, boolean isShow);}

主要的加载Activity,内容不多

public class MainActivity extends Activity {LayoutInflater inflater;LaScrollView sv;LinearLayout llController,llRefresh;LinearLayout llContent;TextView tvView;//是否滚到底boolean isBottom;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);setup();}private void setup(){inflater = LayoutInflater.from(this);sv = (LaScrollView) findViewById(R.id.sv);llController = (LinearLayout) findViewById(R.id.llComtroller);llContent = (LinearLayout) findViewById(R.id.llContent);llRefresh = (LinearLayout) findViewById(R.id.refreshLayout);tvView = (TextView) findViewById(R.id.head_tipsTextView);//为了看起来简洁,更好阅读, 界面十分简易for (int i = 0; i < 40; i++) {TextView tv = new TextView(this);tv.setText("哈哈哈哈啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊");llContent.addView(tv);}//把sv和相关控件联系起来sv.setLlContent(llContent);sv.setLlController(llController);sv.setLlRefresh(llRefresh);sv.setTvView(tvView);sv.init();}}

界面xml文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <com.example.android_test.component.LaScrollView        android:id="@+id/sv"        android:layout_width="fill_parent"        android:layout_height="fill_parent" >        <LinearLayout            android:id="@+id/llComtroller"            android:layout_width="fill_parent"            android:layout_height="fill_parent"            android:orientation="vertical" >            <LinearLayout                android:id="@+id/llContent"                android:layout_width="fill_parent"                android:layout_height="fill_parent"                android:orientation="vertical" >            </LinearLayout>            <include                 android:layout_width="fill_parent"                android:layout_height="wrap_content"                layout="@layout/list_bottom"/>        </LinearLayout>    </com.example.android_test.component.LaScrollView></RelativeLayout>

实现过程还是比较简单的, 代码都在这了 , 没什么其他内容了 ,  源程序在 这里