package com.example.zhuang;import android.content.Context;import android.util.AttributeSet;import android.util.DisplayMetrics;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.view.WindowManager;import android.widget.Scroller;public class MyScrollView extends ViewGroup {  private int mScreeHeight;//屏幕高度  private Scroller mScroller;  private int mLastY;  private int mStart;  private int mEnd;  private Context context;  public MyScrollView(Context context) {    super(context);    initView(context);  }  public MyScrollView(Context context, AttributeSet attrs) {    super(context, attrs);    initView(context);  }  public MyScrollView(Context context, AttributeSet attrs,            int defStyleAttr) {    super(context, attrs, defStyleAttr);    initView(context);  }  private void initView(Context context) {    WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);    //DisplayMetrics 類提供了一種關(guān)于顯示的通用信息，如顯示大小，分辨率和字體。    DisplayMetrics dm = new DisplayMetrics();    wm.getDefaultDisplay().getMetrics(dm);    mScreeHeight = dm.heightPixels;//高度（像素）    mScroller = new Scroller(context);  }  //繼承ViewGroup必須要實(shí)現(xiàn)的方法  @Override  protected void onLayout(boolean changed, int l, int t, int r, int b) {    int childCount = getChildCount();//獲取子view的個(gè)數(shù)    //設(shè)置ViewGroup的高度    MarginLayoutParams mlp = (MarginLayoutParams) getLayoutParams();    mlp.height = mScreeHeight * childCount;    setLayoutParams(mlp);    for (int i = 0; i < childCount; i++) {      View child = getChildAt(i);      if (child.getVisibility() != View.GONE) {        //參數(shù)為相對(duì)父容器的左上右下位置,第三個(gè)參數(shù)必須為r        child.layout(0, i * mScreeHeight, r, (i + 1) * mScreeHeight);      }    }  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    super.onMeasure(widthMeasureSpec, heightMeasureSpec);    int count = getChildCount();    for (int i = 0; i < count; i++) {      View child = getChildAt(i);      measureChild(child, widthMeasureSpec, heightMeasureSpec);    }  }  @Override  public boolean onTouchEvent(MotionEvent event) {    int y = (int) event.getY();//相對(duì)于view的y值，getRawY()是相對(duì)屏幕    switch (event.getAction()) {      case MotionEvent.ACTION_DOWN:        mLastY = y;//上一次的y值        mStart = getScrollY();//記錄觸摸起點(diǎn)        break;      case MotionEvent.ACTION_MOVE:        if(!mScroller.isFinished()) {          mScroller.abortAnimation();//放棄移到最終位置        }        int dy = mLastY - y;//偏移距離        //如果滑動(dòng)距離小于0或大于屏幕高度，不偏移        if(getScrollY()<0){          dy = 0;        }        if(getScrollY() > getHeight()-mScreeHeight){          dy = 0;        }        scrollBy(0,dy);//移動(dòng)        mLastY = y;        break;      case MotionEvent.ACTION_UP:        int dScrollY = checkAlignment();//整體移動(dòng)的距離        if(dScrollY > 0){          if(dScrollY < mScreeHeight / 3){            mScroller.startScroll(0,getScrollY(),0,-dScrollY);          }else{            mScroller.startScroll(0,getScrollY(),0,mScreeHeight-dScrollY);          }        }else{          if(-dScrollY < mScreeHeight / 3){            mScroller.startScroll(0,getScrollY(),0,-dScrollY);          }else{            mScroller.startScroll(0,getScrollY(),0,-mScreeHeight-dScrollY);          }        }        break;    }    postInvalidate();    return true;  }  private int checkAlignment(){     mEnd = getScrollY();//記錄觸摸終點(diǎn)    boolean isUp = ((mEnd - mStart)>0) ? true : false;    int lastPrev = mEnd % mScreeHeight;    int lastNext = mScreeHeight - lastPrev;    if(isUp){      return lastPrev;//向上    }else      return -lastNext;  }  @Override  public void computeScroll() {    super.computeScroll();    if(mScroller.computeScrollOffset()){//返回true，表示還未移動(dòng)完      scrollTo(0,mScroller.getCurrY());//移到當(dāng)前位置      postInvalidate();      //invalidate()是用來(lái)刷新View的，必須是在UI線程中進(jìn)行工作。      //postInvalidate()可以在非UI線程調(diào)用    }  }}

DisplayMetrics metric = new DisplayMetrics(); //API 17之后使用，獲取的像素寬高包含虛擬鍵所占空間，在API 17之前通過(guò)反射獲取 context.getWindowManager().getDefaultDisplay().getRealMetrics(metric); //獲取的像素寬高不包含虛擬鍵所占空間 //context.getWindowManager().getDefaultDisplay().getMetrics(metric); int width = metric.widthPixels; // 寬度（像素） int height = metric.heightPixels; // 高度（像素） float density = metric.density; // dp縮放因子 int densityDpi = metric.densityDpi; // 廣義密度 float xdpi = metric.xdpi;//x軸方向的真實(shí)密度 float ydpi = metric.ydpi;//y軸方向的真實(shí)密度 

private int getStatusBarHeight() {   Rect rect = new Rect();   getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);   return rect.top; }