Android UI实现多行文本折叠展开效果

 <LinearLayout
 android:id="@+id/description_layout"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:orientation="vertical"
 android:paddingLeft="12dip"
 android:paddingRight="12dip"
 android:paddingTop="5dip" >

 <TextView
 android:id="@+id/description_view"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:textColor="@android:color/black"
 android:textSize="18dip" >
 </TextView>

 <ImageView
 android:id="@+id/expand_view"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_gravity="right"
 android:paddingBottom="5dip"
 android:paddingLeft="5dip"
 android:paddingRight="5dip"
 android:paddingTop="5dip"
 android:src="@drawable/text_ic_expand"
 android:visibility="gone" />
 </LinearLayout>

public class MainActivity extends Activity {
 TextView descriptionView;
 View layoutView ,expandView; //LinearLayout布局和ImageView
 int maxDescripLine = 3; //TextView默认最大展示行数

 //在OnCreate中初始化
 {
 layoutView = findViewById(R.id.description_layout);
 descriptionView = (TextView)findViewById(R.id.description_view);
 expandView = findViewById(R.id.expand_view);
 }
}

 //设置文本
 descriptionView.setText(getText(R.string.content));

 //descriptionView设置默认显示高度
 descriptionView.setHeight(descriptionView.getLineHeight() * maxDescripLine);
 //根据高度来判断是否需要再点击展开
 descriptionView.post(new Runnable() {

 @Override
 public void run() {
 expandView.setVisibility(descriptionView.getLineCount() > maxDescripLine ? View.VISIBLE : View.GONE);
 }
 }); 

 layoutView.setOnClickListener(new View.OnClickListener() {
 boolean isExpand;//是否已展开的状态

 @Override
 public void onClick(View v) {
 isExpand = !isExpand;
 descriptionView.clearAnimation();//清楚动画效果
 final int deltaValue;//默认高度，即前边由maxLine确定的高度
 final int startValue = descriptionView.getHeight();//起始高度
 int durationMillis = 350;//动画持续时间
 if (isExpand) {
 /**
 * 折叠动画
 * 从实际高度缩回起始高度
 */
 deltaValue = descriptionView.getLineHeight() * descriptionView.getLineCount() - startValue;
 RotateAnimation animation = new RotateAnimation(0, 180, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 expandView.startAnimation(animation);
 } else {
 /**
 * 展开动画
 * 从起始高度增长至实际高度
 */
 deltaValue = descriptionView.getLineHeight() * maxDescripLine - startValue;
 RotateAnimation animation = new RotateAnimation(180, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 expandView.startAnimation(animation);
 }
 Animation animation = new Animation() {
 protected void applyTransformation(float interpolatedTime, Transformation t) { //根据ImageView旋转动画的百分比来显示textview高度，达到动画效果
 descriptionView.setHeight((int) (startValue + deltaValue * interpolatedTime));
 }
 };
 animation.setDuration(durationMillis);
 descriptionView.startAnimation(animation);
 }
 });

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="MoreTextStyle">
 <attr name="textSize" format="dimension"/>
 <attr name="textColor" format="color"/>
 <attr name="maxLine" format="integer" />
 <attr name="text" format="string" />
 </declare-styleable>
</resources>

public class MoreTextView extends LinearLayout{
 protected TextView contentView; //文本正文
 protected ImageView expandView; //展开按钮

 //对应styleable中的属性
 protected int textColor; 
 protected float textSize;
 protected int maxLine;
 protected String text;

 //默认属性值
 public int defaultTextColor = Color.BLACK;
 public int defaultTextSize = 12;
 public int defaultLine = 3;

 //....实现部分略
}

 public MoreTextView(Context context, AttributeSet attrs) {
 super(context, attrs);
 initalize(); 
 initWithAttrs(context, attrs); 
 bindListener();
 }

//初始化并添加View
protected void initalize() {
 setOrientation(VERTICAL); //设置垂直布局
 setGravity(Gravity.RIGHT); //右对齐
 //初始化textView并添加
 contentView = new TextView(getContext());
 addView(contentView, LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
 //初始化ImageView并添加
 expandView = new ImageView(getContext());
 int padding = dip2px(getContext(), 5);
 expandView.setPadding(padding, padding, padding, padding);
 expandView.setImageResource(R.drawable.text_ic_expand);
 LinearLayout.LayoutParams llp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
 addView(expandView, llp);

 protected void initWithAttrs(Context context, AttributeSet attrs) {
 TypedArray a = context.obtainStyledAttributes(attrs, 
 R.styleable.MoreTextStyle); 
 int textColor = a.getColor(R.styleable.MoreTextStyle_textColor, 
 defaultTextColor); //取颜色值，默认defaultTextColor
 textSize = a.getDimensionPixelSize(R.styleable.MoreTextStyle_textSize, defaultTextSize);//取颜字体大小，默认defaultTextSize
 maxLine = a.getInt(R.styleable.MoreTextStyle_maxLine, defaultLine);//取颜显示行数，默认defaultLine
 text = a.getString(R.styleable.MoreTextStyle_text);//取文本内容

 //绑定到textView bindTextView(textColor,textSize,maxLine,text);

 a.recycle();//回收释放
 }

 //绑定到textView 
 protected void bindTextView(int color,float size,final int line,String text){
 contentView.setTextColor(color);
 contentView.setTextSize(TypedValue.COMPLEX_UNIT_PX,size);
 contentView.setText(text);
 contentView.setHeight(contentView.getLineHeight() * line);
 post(new Runnable() {//前面已讲，不再赘述

 @Override
 public void run() {
 expandView.setVisibility(contentView.getLineCount() > line ? View.VISIBLE : View.GONE);

 }
 });
 }

 //点击展开与折叠，不再赘述
 protected void bindListener(){
 setOnClickListener(new View.OnClickListener() {
 boolean isExpand;

 @Override
 public void onClick(View v) {
 isExpand = !isExpand;
 contentView.clearAnimation();
 final int deltaValue;
 final int startValue = contentView.getHeight();
 int durationMillis = 350;
 if (isExpand) {
 deltaValue = contentView.getLineHeight() * contentView.getLineCount() - startValue;
 RotateAnimation animation = new RotateAnimation(0, 180, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 expandView.startAnimation(animation);
 } else {
 deltaValue = contentView.getLineHeight() * maxLine - startValue;
 RotateAnimation animation = new RotateAnimation(180, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 expandView.startAnimation(animation);
 }
 Animation animation = new Animation() {
 protected void applyTransformation(float interpolatedTime, Transformation t) {
 contentView.setHeight((int) (startValue + deltaValue * interpolatedTime));
 }

 };
 animation.setDuration(durationMillis);
 contentView.startAnimation(animation);
 }
 });
 }

 public TextView getTextView(){
 return contentView;
 }

 public void setText(CharSequence charSequence){
 contentView.setText(charSequence);
 }

 public static int dip2px(Context context, float dipValue){ 
 final float scale = context.getResources().getDisplayMetrics().density; 
 return (int)(dipValue * scale + 0.5f); 
 } 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:more="http://schemas.android.com/apk/res/com.qiao.moretext"
 android:id="@+id/root"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="@android:color/white"
 android:orientation="vertical" >

 <com.qiao.moretext.MoreTextView
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_margin="5dip" 
 more:textColor="@android:color/black"
 more:textSize="18dip"
 more:maxLine="3"
 more:text="@string/content"/>

</LinearLayout>

 MoreTextView content = new MoreTextView(MainActivity.this, null);
 content.setText(getText(R.string.content));
 //然后addview到你要添加的地方

　　当然，聪明如你，可肯定知道怎么定义另外的构造方法来简单实用啦。 
　　–> 
　　MoreTextView(Context context){ 
　　　　//使用默认值直接初始化 
　　　　bindTextView()； 
　　}