android使用Textview实现伸缩效果

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 tools:context=".MainActivity" > 
 
 <!-- 显示文本 --> 
 <TextView 
  android:id="@+id/text_content" 
  android:layout_width="fill_parent" 
  android:layout_height="wrap_content" 
  android:ellipsize="end" 
  android:maxLines="3" 
  android:singleLine="false" /> 
 
 <!-- 更多和箭头 --> 
 <RelativeLayout 
  android:id="@+id/show_more" 
  android:layout_below="@id/text_content" 
  android:layout_alignParentRight="true" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:layout_marginTop="3dip" 
  > 
 
  <TextView 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content" 
   android:layout_alignParentRight="true" 
   android:textSize="13sp" 
   android:textColor="#999" 
   android:layout_marginRight="34dip" 
   android:text="更多" /> 
 
 
  <ImageView 
   android:id="@+id/spread" 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content" 
   android:layout_alignParentRight="true" 
   android:background="@drawable/ic_details_more" /> 
 
  <ImageView 
   android:id="@+id/shrink_up" 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content" 
   android:layout_alignParentRight="true" 
   android:background="@drawable/ic_shrink_up" 
   android:visibility="gone" /> 
 </RelativeLayout> 
</RelativeLayout> 

package com.example.testdemo; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.ImageView; 
import android.widget.RelativeLayout; 
import android.widget.TextView; 
 
public class MainActivity extends Activity implements OnClickListener { 
 
private static final int VIDEO_CONTENT_DESC_MAX_LINE = 3;// 默认展示最大行数3行 
private static final int SHOW_CONTENT_NONE_STATE = 0;// 扩充 
private static final int SHRINK_UP_STATE = 1;// 收起状态 
private static final int SPREAD_STATE = 2;// 展开状态 
private static int mState = SHRINK_UP_STATE;//默认收起状态 
 
private TextView mContentText;// 展示文本内容 
private RelativeLayout mShowMore;// 展示更多 
private ImageView mImageSpread;// 展开 
private ImageView mImageShrinkUp;// 收起 
 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
 
initView(); 
initData(); 
} 
 
private void initView() { 
mContentText = (TextView) findViewById(R.id.text_content); 
mShowMore = (RelativeLayout) findViewById(R.id.show_more); 
mImageSpread = (ImageView) findViewById(R.id.spread); 
mImageShrinkUp = (ImageView) findViewById(R.id.shrink_up); 
mShowMore.setOnClickListener(this); 
 
} 
 
private void initData() { 
mContentText.setText(R.string.txt_info); 
} 
 
@Override 
public void onClick(View v) { 
// TODO Auto-generated method stub 
switch (v.getId()) { 
case R.id.show_more: { 
if (mState == SPREAD_STATE) { 
mContentText.setMaxLines(VIDEO_CONTENT_DESC_MAX_LINE); 
mContentText.requestLayout(); 
mImageShrinkUp.setVisibility(View.GONE); 
mImageSpread.setVisibility(View.VISIBLE); 
mState = SHRINK_UP_STATE; 
} else if (mState == SHRINK_UP_STATE) { 
mContentText.setMaxLines(Integer.MAX_VALUE); 
mContentText.requestLayout(); 
mImageShrinkUp.setVisibility(View.VISIBLE); 
mImageSpread.setVisibility(View.GONE); 
mState = SPREAD_STATE; 
} 
break; 
} 
default: { 
break; 
} 
} 
} 
 
}