仿<赶集生活>client启动动画效果

        demo下载地址: http://yun.baidu.com/s/1i3wqEMh

        由于前几年csdn泄露password的事件，导致我的账号被拿去发广告文章了，联系了管理员帮我把几篇广告文删掉，可是那几篇高质量的文章就这样没了。如今补回当中一篇。是关于怎样实现像赶集生活client第一次启动时的介绍动画的，demo在上面，能够下载来试试效果。有须要的能够在评论里提供邮箱。博主会把project发过去 : )

//FeatureAnimationListener.java

package com.example.animatetest;

import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;

public class FeatureAnimationListener implements AnimationListener {
	private View mAnimView;
	private boolean mAnimIn;
	
	public FeatureAnimationListener(View animView, boolean animIn) {
		mAnimView = animView;
		mAnimIn = animIn;
	}

	@Override
	public void onAnimationEnd(Animation animation) {
		if(!mAnimIn) {
			mAnimView.setVisibility(View.INVISIBLE);
		}
	}

	@Override
	public void onAnimationRepeat(Animation animation) {}

	@Override
	public void onAnimationStart(Animation animation) {
		if(mAnimIn) {
			mAnimView.setVisibility(View.VISIBLE);
		}
	}

}

//OnScrollChangedListener.java

package com.example.animatetest;

public abstract interface OnScrollChangedListener {
	public abstract void onScrollChanged(int top, int oldTop);
}

//ObservableScrollView.java

package com.example.animatetest;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ScrollView;

public class ObservableScrollView extends ScrollView {
	private OnScrollChangedListener onScrollChangedListener;

	public ObservableScrollView(Context context, AttributeSet attrs,
			int defStyle) {
		super(context, attrs, defStyle);
	}

	public ObservableScrollView(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	public ObservableScrollView(Context context) {
		super(context);
	}
	
	@Override
	protected void onScrollChanged(int l, int t, int oldl, int oldt) {
		super.onScrollChanged(l, t, oldl, oldt);
		if(this.onScrollChangedListener != null) {
			onScrollChangedListener.onScrollChanged(t, oldt);
		}
	}

	public void setOnScrollChangedListener(OnScrollChangedListener onScrollChangedListener) {
		this.onScrollChangedListener = onScrollChangedListener;
	}

}

//MainActivity.java

package com.example.animatetest;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;

public class MainActivity extends Activity implements OnGlobalLayoutListener, OnScrollChangedListener {
	private ObservableScrollView mScrollView;
	private View mAnimView;
	private int mScrollViewHeight;
	private int mStartAnimateTop;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		mScrollView = (ObservableScrollView)this.findViewById(R.id.scrollView1);
		mScrollView.getViewTreeObserver().addOnGlobalLayoutListener(this);
		mScrollView.setOnScrollChangedListener(this);
		
		mAnimView = this.findViewById(R.id.anim1);
		mAnimView.setVisibility(View.INVISIBLE);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public void onGlobalLayout() {
		mScrollViewHeight = mScrollView.getHeight();
		mStartAnimateTop = mScrollViewHeight / 3 * 2;
	}

	boolean hasStart = false;
	@Override
	public void onScrollChanged(int top, int oldTop) {
		int animTop = mAnimView.getTop() - top;
		
		if(top > oldTop) {
			if(animTop < mStartAnimateTop && !hasStart) {
				Animation anim1 = AnimationUtils.loadAnimation(this, R.anim.feature_anim2scale_in);
				anim1.setAnimationListener(new FeatureAnimationListener(mAnimView, true));
				
				mAnimView.startAnimation(anim1);
				hasStart = true;
			}
		} else {
			if(animTop > mStartAnimateTop && hasStart) {
				Animation anim1 = AnimationUtils.loadAnimation(this, R.anim.feature_alpha_out);
				anim1.setAnimationListener(new FeatureAnimationListener(mAnimView, false));
				
				mAnimView.startAnimation(anim1);
				hasStart = false;
			}
		}
	}
}

        这里主要是继承ScrollView，重载里面的onScrollChanged方法。监听ScrollView的滑动状态，从而控制动画的显示和消失。