1.重写Scroller

/**
 * 利用这个类来修正ViewPager的滑动速度
 * 我们重写 startScroll方法，忽略传过来的 duration 属性
 * 而是采用我们自己设置的时间
 */
public class FixedSpeedScroller extends Scroller {

    public int mDuration=1500;
    public FixedSpeedScroller(Context context) {
        super(context);
    }

    public FixedSpeedScroller(Context context, Interpolator interpolator) {
        super(context, interpolator);
    }

    public FixedSpeedScroller(Context context, Interpolator interpolator, boolean flywheel) {
        super(context, interpolator, flywheel);
    }

    @Override public void startScroll(int startX, int startY, int dx, int dy) {
        startScroll(startX,startY,dx,dy,mDuration);
    }

    @Override public void startScroll(int startX, int startY, int dx, int dy, int duration) {
        //管你 ViewPager 传来什么时间，我完全不鸟你
        super.startScroll(startX, startY, dx, dy, mDuration);
    }

    public int getmDuration() {
        return mDuration;
    }

    public void setmDuration(int duration) {
        mDuration = duration;
    }
}

2.通过反射来修改 ViewPager的mScroller属性

try {
    Class clazz=Class.forName("android.support.v4.view.ViewPager");
    Field f=clazz.getDeclaredField("mScroller");
    FixedSpeedScroller fixedSpeedScroller=new FixedSpeedScroller(context,new LinearOutSlowInInterpolator());
    fixedSpeedScroller.setmDuration(1000);
    f.setAccessible(true);
    f.set(viewPager,fixedSpeedScroller);
} catch (Exception e) {
    e.printStackTrace();
}

3.viewPager.setCurrentItem(position,true)