Android开发中滑动分页功能实例详解

本文实例讲述了Android开发中滑动分页功能。分享给大家供大家参考，具体如下：

android UI 往右滑动，滑动到最后一页就自动加载数据并显示

如图：

Java代码：

package cn.anycall.ju;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.Toast;
import cn.anycall.ju.ScrollLayout.OnScreenChangeListenerDataLoad;

public class AllAppList extends Activity {
  private ScrollLayout mScrollLayout;
  private static final float APP_PAGE_SIZE = 4.0f;
  private Context mContext;
  private PageControlView pageControl;
  public MyHandler myHandler;
  public int n=0;
  private DataLoading dataLoad;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    mContext = this;
    setContentView(R.layout.main);
    dataLoad = new DataLoading();
    mScrollLayout = (ScrollLayout)findViewById(R.id.ScrollLayoutTest);
    myHandler = new MyHandler(this,1);
    //起一个线程更新数据
    MyThread m = new MyThread();
    new Thread(m).start();
  }
  
  public onItemClickListener listener = new onItemClickListener() {
    public void onItemClick(AdapterView parent, View view, int position,
 long id) {
      // TODO Auto-generated method stub
      System.out.println("position="+position);
    }
  };
  @Override
  protected void onDestroy() {
    // TODO Auto-generated method stub
    android.os.Process.killProcess(android.os.Process.myPid());
    super.onDestroy();
  }
  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    if (keyCode == KeyEvent.KEYCODE_BACK) {
      finish();
      return true;
    }
    return super.onKeyDown(keyCode, event);
  }
  // 更新后台数据
  class MyThread implements Runnable {
    public void run() {
      try {
 Thread.sleep(1000*3);
      } catch (InterruptedException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
      }
      String msglist = "1";
      Message msg = new Message();
      Bundle b = new Bundle();// 存放数据
      b.putString("rmsg", msglist);
      msg.setData(b);
      AllAppList.this.myHandler.sendMessage(msg); // 向Handler发送消息,更新UI
    }
  }
  class MyHandler extends Handler {
    private AllAppList mContext;
    public MyHandler(Context conn,int a) {
      mContext = (AllAppList)conn;
    }
    public MyHandler(Looper L) {
      super(L);
    }
    // 子类必须重写此方法,接受数据
    @Override
    public void handleMessage(Message msg) {
      // TODO Auto-generated method stub
      super.handleMessage(msg);
      Bundle b = msg.getData();
      String rmsg = b.getString("rmsg");
      if ("1".equals(rmsg)) {
 // do nothing
  List list = new ArrayList();
  for(int i =0;i<16;i++){
    n++;
    Map map = new HashMap();
     map.put("name", n);
     list.add(map);
  }
 int pageNo = (int)Math.ceil( list.size()/APP_PAGE_SIZE);
 for (int i = 0; i < pageNo; i++) {
   GridView appPage = new GridView(mContext);
   // get the "i" page data
   appPage.setAdapter(new AppAdapter(mContext, list, i));
   appPage.setNumColumns(2);
   appPage.setonItemClickListener(listener);
   mScrollLayout.addView(appPage);
 }
 //加载分页
 pageControl = (PageControlView) findViewById(R.id.pageControl);
 pageControl.bindScrollViewGroup(mScrollLayout);
 //加载分页数据
 dataLoad.bindScrollViewGroup(mScrollLayout);
 }
      }
    }
  //分页数据
  class DataLoading {
    private int count;
    public void bindScrollViewGroup(ScrollLayout scrollViewGroup) {
      this.count=scrollViewGroup.getChildCount();
      scrollViewGroup.setonScreenChangeListenerDataLoad(new onScreenChangeListenerDataLoad() {
 public void onScreenChange(int currentIndex) {
   // TODO Auto-generated method stub
   generatePageControl(currentIndex);
 }
      });
    }
    private void generatePageControl(int currentIndex){
      //如果到最后一页，就加载16条记录
      if(count==currentIndex+1){
 MyThread m = new MyThread();
 new Thread(m).start();
      }
    }
  }
}

Java代码：

package cn.anycall.ju;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.Toast;
import cn.anycall.ju.ScrollLayout.OnScreenChangeListenerDataLoad;

public class AllAppList extends Activity {
  private ScrollLayout mScrollLayout;
  private static final float APP_PAGE_SIZE = 4.0f;
  private Context mContext;
  private PageControlView pageControl;
  public MyHandler myHandler;
  public int n=0;
  private DataLoading dataLoad;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    mContext = this;
    setContentView(R.layout.main);
    dataLoad = new DataLoading();
    mScrollLayout = (ScrollLayout)findViewById(R.id.ScrollLayoutTest);
    myHandler = new MyHandler(this,1);
    //起一个线程更新数据
    MyThread m = new MyThread();
    new Thread(m).start();
  }
  
  public onItemClickListener listener = new onItemClickListener() {
    public void onItemClick(AdapterView parent, View view, int position,
 long id) {
      // TODO Auto-generated method stub
      System.out.println("position="+position);
    }
  };
  @Override
  protected void onDestroy() {
    // TODO Auto-generated method stub
    android.os.Process.killProcess(android.os.Process.myPid());
    super.onDestroy();
  }
  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    if (keyCode == KeyEvent.KEYCODE_BACK) {
      finish();
      return true;
    }
    return super.onKeyDown(keyCode, event);
  }
  // 更新后台数据
  class MyThread implements Runnable {
    public void run() {
      try {
 Thread.sleep(1000*3);
      } catch (InterruptedException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
      }
      String msglist = "1";
      Message msg = new Message();
      Bundle b = new Bundle();// 存放数据
      b.putString("rmsg", msglist);
      msg.setData(b);
      AllAppList.this.myHandler.sendMessage(msg); // 向Handler发送消息,更新UI
    }
  }
  class MyHandler extends Handler {
    private AllAppList mContext;
    public MyHandler(Context conn,int a) {
      mContext = (AllAppList)conn;
    }
    public MyHandler(Looper L) {
      super(L);
    }
    // 子类必须重写此方法,接受数据
    @Override
    public void handleMessage(Message msg) {
      // TODO Auto-generated method stub
      super.handleMessage(msg);
      Bundle b = msg.getData();
      String rmsg = b.getString("rmsg");
      if ("1".equals(rmsg)) {
 // do nothing
  List list = new ArrayList();
  for(int i =0;i<16;i++){
    n++;
    Map map = new HashMap();
     map.put("name", n);
     list.add(map);
  }
 int pageNo = (int)Math.ceil( list.size()/APP_PAGE_SIZE);
 for (int i = 0; i < pageNo; i++) {
   GridView appPage = new GridView(mContext);
   // get the "i" page data
   appPage.setAdapter(new AppAdapter(mContext, list, i));
   appPage.setNumColumns(2);
   appPage.setonItemClickListener(listener);
   mScrollLayout.addView(appPage);
 }
 //加载分页
 pageControl = (PageControlView) findViewById(R.id.pageControl);
 pageControl.bindScrollViewGroup(mScrollLayout);
 //加载分页数据
 dataLoad.bindScrollViewGroup(mScrollLayout);
 }
      }
    }
  //分页数据
  class DataLoading {
    private int count;
    public void bindScrollViewGroup(ScrollLayout scrollViewGroup) {
      this.count=scrollViewGroup.getChildCount();
      scrollViewGroup.setonScreenChangeListenerDataLoad(new onScreenChangeListenerDataLoad() {
 public void onScreenChange(int currentIndex) {
   // TODO Auto-generated method stub
   generatePageControl(currentIndex);
 }
      });
    }
    private void generatePageControl(int currentIndex){
      //如果到最后一页，就加载16条记录
      if(count==currentIndex+1){
 MyThread m = new MyThread();
 new Thread(m).start();
      }
    }
  }
}

Java代码：

package cn.anycall.ju;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.baseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import cn.anycall.ju.R;
public class AppAdapter extends baseAdapter {
  private List mList;
  private Context mContext;
  public static final int APP_PAGE_SIZE = 4;
  private PackageManager pm;
  public AppAdapter(Context context, List list, int page) {
    mContext = context;
    pm = context.getPackageManager();
    mList = new ArrayList();
    int i = page * APP_PAGE_SIZE;
    int iEnd = i+APP_PAGE_SIZE;
    while ((i

Java代码：

package cn.anycall.ju;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.baseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import cn.anycall.ju.R;
public class AppAdapter extends baseAdapter {
  private List mList;
  private Context mContext;
  public static final int APP_PAGE_SIZE = 4;
  private PackageManager pm;
  public AppAdapter(Context context, List list, int page) {
    mContext = context;
    pm = context.getPackageManager();
    mList = new ArrayList();
    int i = page * APP_PAGE_SIZE;
    int iEnd = i+APP_PAGE_SIZE;
    while ((i

Java代码：

package cn.anycall.ju;
import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;
import android.widget.LinearLayout;
import cn.anycall.ju.R;
import cn.anycall.ju.ScrollLayout.OnScreenChangeListener;
public class PageControlView extends LinearLayout {
  private Context context;
  private int count;
  public void bindScrollViewGroup(ScrollLayout scrollViewGroup) {
    this.count=scrollViewGroup.getChildCount();
    System.out.println("count="+count);
    generatePageControl(scrollViewGroup.getCurrentScreenIndex());
    scrollViewGroup.setonScreenChangeListener(new onScreenChangeListener() {
      public void onScreenChange(int currentIndex) {
 // TODO Auto-generated method stub
 generatePageControl(currentIndex);
      }
    });
  }
  public PageControlView(Context context) {
    super(context);
    this.init(context);
  }
  public PageControlView(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.init(context);
  }
  private void init(Context context) {
    this.context=context;
  }
  private void generatePageControl(int currentIndex) {
    this.removeAllViews();
    int pageNum = 6; // 显示多少个
    int pageNo = currentIndex+1; //第几页
    int pageSum = this.count; //总共多少页
    if(pageSum>1){
      int currentNum = (pageNo % pageNum == 0 ? (pageNo / pageNum) - 1
    : (int) (pageNo / pageNum))
    * pageNum;
if (currentNum < 0)
  currentNum = 0;
if (pageNo > pageNum){
  ImageView imageView = new ImageView(context);
  imageView.setImageResource(R.drawable.zuo);
  this.addView(imageView);
}
for (int i = 0; i < pageNum; i++) {
  if ((currentNum + i + 1) > pageSum || pageSum < 2)
    break;
  ImageView imageView = new ImageView(context);
  if(currentNum + i + 1 == pageNo){
    imageView.setImageResource(R.drawable.page_indicator_focused);
  }else{
    imageView.setImageResource(R.drawable.page_indicator);
  }
  this.addView(imageView);
}
if (pageSum > (currentNum + pageNum)) {
  ImageView imageView = new ImageView(context);
  imageView.setImageResource(R.drawable.you);
  this.addView(imageView);
}
    }
  }
}



Java代码：

package cn.anycall.ju;
import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;
import android.widget.LinearLayout;
import cn.anycall.ju.R;
import cn.anycall.ju.ScrollLayout.OnScreenChangeListener;
public class PageControlView extends LinearLayout {
  private Context context;
  private int count;
  public void bindScrollViewGroup(ScrollLayout scrollViewGroup) {
    this.count=scrollViewGroup.getChildCount();
    System.out.println("count="+count);
    generatePageControl(scrollViewGroup.getCurrentScreenIndex());
    scrollViewGroup.setonScreenChangeListener(new onScreenChangeListener() {
      public void onScreenChange(int currentIndex) {
 // TODO Auto-generated method stub
 generatePageControl(currentIndex);
      }
    });
  }
  public PageControlView(Context context) {
    super(context);
    this.init(context);
  }
  public PageControlView(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.init(context);
  }
  private void init(Context context) {
    this.context=context;
  }
  private void generatePageControl(int currentIndex) {
    this.removeAllViews();
    int pageNum = 6; // 显示多少个
    int pageNo = currentIndex+1; //第几页
    int pageSum = this.count; //总共多少页
    if(pageSum>1){
      int currentNum = (pageNo % pageNum == 0 ? (pageNo / pageNum) - 1
    : (int) (pageNo / pageNum))
    * pageNum;
if (currentNum < 0)
  currentNum = 0;
if (pageNo > pageNum){
  ImageView imageView = new ImageView(context);
  imageView.setImageResource(R.drawable.zuo);
  this.addView(imageView);
}
for (int i = 0; i < pageNum; i++) {
  if ((currentNum + i + 1) > pageSum || pageSum < 2)
    break;
  ImageView imageView = new ImageView(context);
  if(currentNum + i + 1 == pageNo){
    imageView.setImageResource(R.drawable.page_indicator_focused);
  }else{
    imageView.setImageResource(R.drawable.page_indicator);
  }
  this.addView(imageView);
}
if (pageSum > (currentNum + pageNum)) {
  ImageView imageView = new ImageView(context);
  imageView.setImageResource(R.drawable.you);
  this.addView(imageView);
}
    }
  }
}



Java代码：

package cn.anycall.ju;
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;

public class ScrollLayout extends ViewGroup {
  private static final String TAG = "ScrollLayout";
  private Scroller mScroller;
  private VelocityTracker mVelocityTracker;
  private int mCurScreen;
  private int mDefaultScreen = 0;
  private static final int TOUCH_STATE_REST = 0;
  private static final int TOUCH_STATE_SCROLLING = 1;
  private static final int SNAP_VELOCITY = 600;
  private int mTouchState = TOUCH_STATE_REST;
  private int mTouchSlop;
  private float mLastMotionX;
  private float mLastMotionY;
  private int currentScreenIndex = 0;
  public int getCurrentScreenIndex() {
    return currentScreenIndex;
  }
  public void setCurrentScreenIndex(int currentScreenIndex) {
    this.currentScreenIndex = currentScreenIndex;
  }
  public ScrollLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
    // TODO Auto-generated constructor stub
  }
  public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    // TODO Auto-generated constructor stub
    mScroller = new Scroller(context);
    mCurScreen = mDefaultScreen;
    mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
  }
  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    // TODO Auto-generated method stub
    int childLeft = 0;
    final int childCount = getChildCount();
    System.out.println("childCount=" + childCount);
    for (int i = 0; i < childCount; i++) {
      final View childView = getChildAt(i);
      if (childView.getVisibility() != View.GONE) {
 final int childWidth = childView.getMeasuredWidth();
 childView.layout(childLeft, 0, childLeft + childWidth,
     childView.getMeasuredHeight());
 childLeft += childWidth;
      }
    }
  }
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    Log.e(TAG, "onMeasure");
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    final int width = MeasureSpec.getSize(widthMeasureSpec);
    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    if (widthMode != MeasureSpec.EXACTLY) {
      throw new IllegalStateException(
   "ScrollLayout only canmCurScreen run at EXACTLY mode!");
    }
    final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    if (heightMode != MeasureSpec.EXACTLY) {
      throw new IllegalStateException(
   "ScrollLayout only can run at EXACTLY mode!");
    }
    // The children are given the same width and height as the scrollLayout
    final int count = getChildCount();
    for (int i = 0; i < count; i++) {
      getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
    }
    System.out.println("moving to screen " + mCurScreen);
    scrollTo(mCurScreen * width, 0);
  }
  
  public void snapToDestination() {
    final int screenWidth = getWidth();
    final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
    snapToScreen(destScreen);
  }
  public void snapToScreen(int whichScreen) {
    // get the valid layout page
    whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
    if (getScrollX() != (whichScreen * getWidth())) {
      final int delta = whichScreen * getWidth() - getScrollX();
      mScroller.startScroll(getScrollX(), 0, delta, 0,
   Math.abs(delta) * 2);
      mCurScreen = whichScreen;
      invalidate(); // Redraw the layout
    }
  }
  public void setToScreen(int whichScreen) {
    whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
    mCurScreen = whichScreen;
    scrollTo(whichScreen * getWidth(), 0);
  }
  public int getCurScreen() {
    return mCurScreen;
  }
  @Override
  public void computeScroll() {
    // TODO Auto-generated method stub
    if (mScroller.computeScrollOffset()) {
      scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      postInvalidate();
    }
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    if (mVelocityTracker == null) {
      mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(event);
    final int action = event.getAction();
    final float x = event.getX();
    final float y = event.getY();
    switch (action) {
    case MotionEvent.ACTION_DOWN:
      Log.e(TAG, "event down!");
      if (!mScroller.isFinished()) {
 mScroller.abortAnimation();
      }
      mLastMotionX = x;
      break;
    case MotionEvent.ACTION_MOVE:
      int deltaX = (int) (mLastMotionX - x);
      mLastMotionX = x;
      scrollBy(deltaX, 0);
      break;
    case MotionEvent.ACTION_UP:
      Log.e(TAG, "event : up");
      // if (mTouchState == TOUCH_STATE_SCROLLING) {
      final VelocityTracker velocityTracker = mVelocityTracker;
      velocityTracker.computeCurrentVelocity(1000);
      int velocityX = (int) velocityTracker.getXVelocity();
      Log.e(TAG, "velocityX:" + velocityX);
      if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
 // Fling enough to move left
 Log.e(TAG, "snap left");
 onScreenChangeListener.onScreenChange(mCurScreen - 1);
 System.out.println("mCurScreen=" + (mCurScreen - 1));
 snapToScreen(mCurScreen - 1);
      } else if (velocityX < -SNAP_VELOCITY
   && mCurScreen < getChildCount() - 1) {
 // Fling enough to move right
 Log.e(TAG, "snap right");
 onScreenChangeListener.onScreenChange(mCurScreen + 1);
 //只往右移动才加载数据
 onScreenChangeListenerDataLoad.onScreenChange(mCurScreen+1);
 snapToScreen(mCurScreen + 1);
      } else {
 snapToDestination();
      }
      if (mVelocityTracker != null) {
 mVelocityTracker.recycle();
 mVelocityTracker = null;
      }
      // }
      mTouchState = TOUCH_STATE_REST;
      break;
    case MotionEvent.ACTION_CANCEL:
      mTouchState = TOUCH_STATE_REST;
      break;
    }
    return true;
  }
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev) {
    // TODO Auto-generated method stub
    Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop);
    final int action = ev.getAction();
    if ((action == MotionEvent.ACTION_MOVE)
 && (mTouchState != TOUCH_STATE_REST)) {
      return true;
    }
    final float x = ev.getX();
    final float y = ev.getY();
    switch (action) {
    case MotionEvent.ACTION_MOVE:
      final int xDiff = (int) Math.abs(mLastMotionX - x);
      if (xDiff > mTouchSlop) {
 mTouchState = TOUCH_STATE_SCROLLING;
      }
      break;
    case MotionEvent.ACTION_DOWN:
      mLastMotionX = x;
      mLastMotionY = y;
      mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
   : TOUCH_STATE_SCROLLING;
      break;
    case MotionEvent.ACTION_CANCEL:
    case MotionEvent.ACTION_UP:
      mTouchState = TOUCH_STATE_REST;
      break;
    }
    return mTouchState != TOUCH_STATE_REST;
  }
  //分页监听
  public interface onScreenChangeListener {
    void onScreenChange(int currentIndex);
  }
  private onScreenChangeListener onScreenChangeListener;
  public void setonScreenChangeListener(
      onScreenChangeListener onScreenChangeListener) {
    this.onScreenChangeListener = onScreenChangeListener;
  }
  //动态数据监听
  public interface onScreenChangeListenerDataLoad {
    void onScreenChange(int currentIndex);
  }
  private onScreenChangeListenerDataLoad onScreenChangeListenerDataLoad;
  public void setonScreenChangeListenerDataLoad(onScreenChangeListenerDataLoad onScreenChangeListenerDataLoad) {
    this.onScreenChangeListenerDataLoad = onScreenChangeListenerDataLoad;
  }
}



Java代码

package cn.anycall.ju;
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;

public class ScrollLayout extends ViewGroup {
  private static final String TAG = "ScrollLayout";
  private Scroller mScroller;
  private VelocityTracker mVelocityTracker;
  private int mCurScreen;
  private int mDefaultScreen = 0;
  private static final int TOUCH_STATE_REST = 0;
  private static final int TOUCH_STATE_SCROLLING = 1;
  private static final int SNAP_VELOCITY = 600;
  private int mTouchState = TOUCH_STATE_REST;
  private int mTouchSlop;
  private float mLastMotionX;
  private float mLastMotionY;
  private int currentScreenIndex = 0;
  public int getCurrentScreenIndex() {
    return currentScreenIndex;
  }
  public void setCurrentScreenIndex(int currentScreenIndex) {
    this.currentScreenIndex = currentScreenIndex;
  }
  public ScrollLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
    // TODO Auto-generated constructor stub
  }
  public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    // TODO Auto-generated constructor stub
    mScroller = new Scroller(context);
    mCurScreen = mDefaultScreen;
    mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
  }
  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    // TODO Auto-generated method stub
    int childLeft = 0;
    final int childCount = getChildCount();
    System.out.println("childCount=" + childCount);
    for (int i = 0; i < childCount; i++) {
      final View childView = getChildAt(i);
      if (childView.getVisibility() != View.GONE) {
 final int childWidth = childView.getMeasuredWidth();
 childView.layout(childLeft, 0, childLeft + childWidth,
     childView.getMeasuredHeight());
 childLeft += childWidth;
      }
    }
  }
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    Log.e(TAG, "onMeasure");
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    final int width = MeasureSpec.getSize(widthMeasureSpec);
    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    if (widthMode != MeasureSpec.EXACTLY) {
      throw new IllegalStateException(
   "ScrollLayout only canmCurScreen run at EXACTLY mode!");
    }
    final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    if (heightMode != MeasureSpec.EXACTLY) {
      throw new IllegalStateException(
   "ScrollLayout only can run at EXACTLY mode!");
    }
    // The children are given the same width and height as the scrollLayout
    final int count = getChildCount();
    for (int i = 0; i < count; i++) {
      getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
    }
    System.out.println("moving to screen " + mCurScreen);
    scrollTo(mCurScreen * width, 0);
  }
  
  public void snapToDestination() {
    final int screenWidth = getWidth();
    final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
    snapToScreen(destScreen);
  }
  public void snapToScreen(int whichScreen) {
    // get the valid layout page
    whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
    if (getScrollX() != (whichScreen * getWidth())) {
      final int delta = whichScreen * getWidth() - getScrollX();
      mScroller.startScroll(getScrollX(), 0, delta, 0,
   Math.abs(delta) * 2);
      mCurScreen = whichScreen;
      invalidate(); // Redraw the layout
    }
  }
  public void setToScreen(int whichScreen) {
    whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
    mCurScreen = whichScreen;
    scrollTo(whichScreen * getWidth(), 0);
  }
  public int getCurScreen() {
    return mCurScreen;
  }
  @Override
  public void computeScroll() {
    // TODO Auto-generated method stub
    if (mScroller.computeScrollOffset()) {
      scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      postInvalidate();
    }
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    if (mVelocityTracker == null) {
      mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(event);
    final int action = event.getAction();
    final float x = event.getX();
    final float y = event.getY();
    switch (action) {
    case MotionEvent.ACTION_DOWN:
      Log.e(TAG, "event down!");
      if (!mScroller.isFinished()) {
 mScroller.abortAnimation();
      }
      mLastMotionX = x;
      break;
    case MotionEvent.ACTION_MOVE:
      int deltaX = (int) (mLastMotionX - x);
      mLastMotionX = x;
      scrollBy(deltaX, 0);
      break;
    case MotionEvent.ACTION_UP:
      Log.e(TAG, "event : up");
      // if (mTouchState == TOUCH_STATE_SCROLLING) {
      final VelocityTracker velocityTracker = mVelocityTracker;
      velocityTracker.computeCurrentVelocity(1000);
      int velocityX = (int) velocityTracker.getXVelocity();
      Log.e(TAG, "velocityX:" + velocityX);
      if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
 // Fling enough to move left
 Log.e(TAG, "snap left");
 onScreenChangeListener.onScreenChange(mCurScreen - 1);
 System.out.println("mCurScreen=" + (mCurScreen - 1));
 snapToScreen(mCurScreen - 1);
      } else if (velocityX < -SNAP_VELOCITY
   && mCurScreen < getChildCount() - 1) {
 // Fling enough to move right
 Log.e(TAG, "snap right");
 onScreenChangeListener.onScreenChange(mCurScreen + 1);
 //只往右移动才加载数据
 onScreenChangeListenerDataLoad.onScreenChange(mCurScreen+1);
 snapToScreen(mCurScreen + 1);
      } else {
 snapToDestination();
      }
      if (mVelocityTracker != null) {
 mVelocityTracker.recycle();
 mVelocityTracker = null;
      }
      // }
      mTouchState = TOUCH_STATE_REST;
      break;
    case MotionEvent.ACTION_CANCEL:
      mTouchState = TOUCH_STATE_REST;
      break;
    }
    return true;
  }
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev) {
    // TODO Auto-generated method stub
    Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop);
    final int action = ev.getAction();
    if ((action == MotionEvent.ACTION_MOVE)
 && (mTouchState != TOUCH_STATE_REST)) {
      return true;
    }
    final float x = ev.getX();
    final float y = ev.getY();
    switch (action) {
    case MotionEvent.ACTION_MOVE:
      final int xDiff = (int) Math.abs(mLastMotionX - x);
      if (xDiff > mTouchSlop) {
 mTouchState = TOUCH_STATE_SCROLLING;
      }
      break;
    case MotionEvent.ACTION_DOWN:
      mLastMotionX = x;
      mLastMotionY = y;
      mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
   : TOUCH_STATE_SCROLLING;
      break;
    case MotionEvent.ACTION_CANCEL:
    case MotionEvent.ACTION_UP:
      mTouchState = TOUCH_STATE_REST;
      break;
    }
    return mTouchState != TOUCH_STATE_REST;
  }
  //分页监听
  public interface onScreenChangeListener {
    void onScreenChange(int currentIndex);
  }
  private onScreenChangeListener onScreenChangeListener;
  public void setonScreenChangeListener(
      onScreenChangeListener onScreenChangeListener) {
    this.onScreenChangeListener = onScreenChangeListener;
  }
  //动态数据监听
  public interface onScreenChangeListenerDataLoad {
    void onScreenChange(int currentIndex);
  }
  private onScreenChangeListenerDataLoad onScreenChangeListenerDataLoad;
  public void setonScreenChangeListenerDataLoad(onScreenChangeListenerDataLoad onScreenChangeListenerDataLoad) {
    this.onScreenChangeListenerDataLoad = onScreenChangeListenerDataLoad;
  }
}



main.xml



  












  









app_item.xml




   
 
 
 
   
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