注意：本次修改，修补了之前的部分bug

android中展开动画主要有2中，Translate和Scale，但运行效果并不像javascript中jQuery(id).slideDown()那么完美，在这里，我们借助动画机制，实现ListView的展开Expand Open，收缩 Expand Close动画。

这些效果在《去哪儿旅行app》和《酷狗音乐app》被广泛使用，我们这里模仿ListView的展开收缩式动画。

先来看图说话，点击item，被点击的Item以下部分会慢慢下滑。

好了，上代码

dimens.xml，这里是重点，因为下滑的前提是，尺寸必须是已知的，否则无法正常下滑

<dimen name="bottom_item_height">50dip</dimen>
<!--防止布局bug，所以需要设置一个数值区间大于bottom_item_height的复数-->
<dimen name="_bottom_item_height">-50.5dip</dimen>

主布局文件listview_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/main_listview"android:layout_width="match_parent"android:layout_height="match_parent"android:listSelector="@android:color/transparent"android:dividerHeight="0.7dip"android:choiceMode="none"android:divider="#d7d7d7"android:orientation="vertical" ></ListView>

listview_item.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical" ><LinearLayoutandroid:layout_width="match_parent"android:layout_height="50dip" android:orientation="horizontal"android:paddingLeft="15dip"android:paddingRight="15dip"><TextViewandroid:id="@+id/song_id_title_tv"android:layout_width="0dip"android:layout_height="wrap_content"android:layout_gravity="center_vertical"android:layout_weight="1"android:text="一片艳阳天"android:textColor="#333333"android:textSize="18sp" /><ImageViewandroid:id="@+id/song_id_switcher_btn"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_vertical"android:src="@drawable/kg_item_ic_btn_toggle_menu_default" /></LinearLayout><LinearLayoutandroid:id="@+id/song_id_panel_li"android:layout_width="match_parent"android:layout_height="@@dimen/bottom_item_height"android:layout_marginBottom="@dimen/_bottom_item_height"android:background="#333333"android:gravity="center_vertical"android:orientation="horizontal" ><ImageViewandroid:layout_weight="1"android:layout_width="0dip"android:id="@+id/imageView1"android:layout_height="match_parent"android:scaleType="center"android:src="@drawable/kg_ic_player_menu_download" /><ImageViewandroid:id="@+id/imageView2"android:layout_weight="1"android:layout_width="0dip"android:layout_height="match_parent"android:scaleType="center"android:src="@drawable/audio_identify_add_press" /><ImageViewandroid:id="@+id/imageView3"android:layout_weight="1"android:layout_width="0dip"android:layout_height="match_parent"android:scaleType="center"android:src="@drawable/audio_identify_share_press" /><ImageViewandroid:id="@+id/imageView4"android:layout_weight="1"android:layout_width="0dip"android:layout_height="match_parent"android:scaleType="center"android:src="@drawable/fm_distinguish_favorite" /></LinearLayout>
</LinearLayout>

自定义动画

package com.example.explistview;import android.view.View;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.LinearLayout.LayoutParams;import com.example.actiontabbar.R;public class ExpandAnimation extends Animation {private View mTargetView;private boolean isExpandDown;public ExpandAnimation(View mTargetView, boolean isExpandDown,int defaultHeight) {super();this.mTargetView = mTargetView;this.isExpandDown = isExpandDown;setDuration(500L);setInterpolator(new AccelerateDecelerateInterpolator());setFillAfter(true);resetViewHeight(mTargetView, defaultHeight);}/*** 动画开始前，务必保证targetView的高度是存在的* @param v* @param defaultHeight*/private void resetViewHeight(View v,int defaultHeight) {LayoutParams lp = (LayoutParams) v.getLayoutParams();lp.height = v.getContext().getResources().getDimensionPixelSize(R.dimen.bottom_item_height);v.setLayoutParams(lp);}@Overrideprotected void applyTransformation(float interpolatedTime, Transformation t) {super.applyTransformation(interpolatedTime, t);int height = mTargetView.getHeight();/*** 注意 这里的 LayoutParams 类型应该和mTargetView的parentView相关，* 比如LinearLayout,这里的类型应该是android.widget.LinearLayout.LayoutParams* 不推荐使用 ViewGroup.LayoutParams,因为不能改变外边距*/LayoutParams layoutParams = (LayoutParams) mTargetView.getLayoutParams();if(isExpandDown){layoutParams.bottomMargin = -height  + (int) (height*interpolatedTime);}else{layoutParams.bottomMargin = -(int) (height*interpolatedTime);}mTargetView.setLayoutParams(layoutParams);mTargetView.getParent().requestLayout();}
}

Activity文件

package com.example.explistview;import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout.LayoutParams;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;import com.example.actiontabbar.R;
import com.nineoldandroids.view.ViewHelper;
import com.nineoldandroids.view.ViewPropertyAnimator;public class AnimExpandActivity extends ActionBarActivity {private ListView mListView;private final List<Song> songList = new ArrayList<AnimExpandActivity.Song>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.listview_layout);mListView = (ListView) findViewById(R.id.main_listview);loadTestData();mListView.setAdapter(new ListSongItemAdapter(this, songList));}private void loadTestData() {songList.add(new Song("苏有朋-珍惜", false));songList.add(new Song("崔子格-卜卦", false));songList.add(new Song("吴奇隆-祝你一路顺风", false));songList.add(new Song("马天宇-该死的温柔", false));songList.add(new Song("陈奕迅-梦想天空分外蓝", false));songList.add(new Song("陈奕迅-爱情转移", false));songList.add(new Song("陈奕迅-十年", false));songList.add(new Song("张宇-雨一直下", false));songList.add(new Song("王筝-我们都是好孩子", false));songList.add(new Song("筷子兄弟-小苹果", false));songList.add(new Song("筷子兄弟-老男孩", false));songList.add(new Song("成龙-神话", false));songList.add(new Song("金莎-星月神话", false));songList.add(new Song("金莎-相思垢", false));songList.add(new Song("许嵩-断桥残雪", false));songList.add(new Song("许嵩-半城烟沙", false));songList.add(new Song("许嵩-灰色头像", false));songList.add(new Song("许嵩-庐州月", false));songList.add(new Song("陈坤-好久没回家", false));}private class ListSongItemAdapter extends BaseAdapter {private final List<Song> dataSource = new ArrayList<AnimExpandActivity.Song>();private LayoutInflater mLayoutInflater = null;private int dimensionPixelSize = 0;public ListSongItemAdapter(Context cxt, List<Song> dataSource) {this.dataSource.addAll(dataSource);mLayoutInflater = LayoutInflater.from(cxt);dimensionPixelSize  = cxt.getResources().getDimensionPixelSize(R.dimen.bottom_item_height);}@Overridepublic int getCount() {return dataSource.size();}@Overridepublic Object getItem(int position) {return dataSource.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {SongViewHolder songViewHolder = null;if (convertView == null|| !SongViewHolder.class.isInstance(convertView.getTag())) {convertView = mLayoutInflater.inflate(R.layout.listview_item,null);songViewHolder = new SongViewHolder(convertView);convertView.setTag(songViewHolder);} else {songViewHolder = (SongViewHolder) convertView.getTag();}Song song = dataSource.get(position);LayoutParams lp = (LayoutParams) songViewHolder.targetPanel.getLayoutParams();if(song.isOpen){ViewHelper.setRotation(songViewHolder.switcherIv, 180f);lp.bottomMargin = 0;lp.height =  dimensionPixelSize;}else{ViewHelper.setRotation(songViewHolder.switcherIv, 0f);lp.bottomMargin = - dimensionPixelSize;//高度是0,lp.bottomMargin值无效，这里之所以设置高度为0，因为为了防止布局耗时导致绘制不及时，从而出现错误显示lp.height = 0;}songViewHolder.targetPanel.setLayoutParams(lp);songViewHolder.switcherIv.setOnClickListener(switcherClickListener);songViewHolder.switcherIv.setTag(position);songViewHolder.titleTv.setText(position + " " + song.name);return convertView;}}private class Song implements Serializable {private String name;private boolean isOpen;public Song(String name, boolean isOpen) {super();this.name = name;this.isOpen = isOpen;}public String getName() {return name;}public void setName(String name) {this.name = name;}public void setOpen(boolean isOpen) {this.isOpen = isOpen;}public boolean isOpen() {return isOpen;}@Overridepublic String toString() {return "Song [name=" + name + ", isOpen=" + isOpen + "]";}}private class SongViewHolder implements Serializable {private View contentView;private TextView titleTv;private ImageView switcherIv;private View targetPanel;public SongViewHolder(View contentView) {this.contentView = contentView;titleTv = (TextView) contentView.findViewById(R.id.song_id_title_tv);switcherIv = (ImageView) contentView.findViewById(R.id.song_id_switcher_btn);targetPanel = contentView.findViewById(R.id.song_id_panel_li);}}private View.OnClickListener switcherClickListener = new View.OnClickListener() {@Overridepublic void onClick(View v) {int position = (Integer) v.getTag();final BaseAdapter adapter = (BaseAdapter) mListView.getAdapter();Song item = (Song) adapter.getItem(position);item.setOpen(!item.isOpen());ViewGroup itemView = (ViewGroup) v.getParent().getParent();SongViewHolder songViewHolder = (SongViewHolder) itemView.getTag();Toast.makeText(AnimExpandActivity.this,"position=" + position + ",title=" + item.getName(),Toast.LENGTH_SHORT).show();int defaultHeight = getResources().getDimensionPixelSize(R.dimen.bottom_item_height);itemView.startAnimation(new ExpandAnimation(songViewHolder.targetPanel, item.isOpen(),defaultHeight));rotateSwitcherIcon(v, item);}};/*** 旋转切换图标* @param v* @param item*/private void rotateSwitcherIcon(View v, Song item){float degree = item.isOpen() ? 180 : 0;ViewPropertyAnimator.animate(v).setDuration(500).setInterpolator(new AccelerateDecelerateInterpolator()).rotation(degree).start();}}

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这里使用了较为原始的自定义动画的方式，推荐读者能够使用 属性动画自定义这种实现

可参考链接 http://blog.csdn.net/lingling1420q/article/details/38678493

目前为止，这个例子还需要进行优化，等时间再说吧。

try doing it!