Android下Button实现图文混排效果

package fry;

import com.example.buttonDemo1.R;

import android.app.Activity;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.style.ImageSpan;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnFocusChangeListener;
import android.view.View.OnTouchListener;
import android.widget.Button;

public class Activity02 extends Activity {
  private Button btn_big;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity02);
    btn_big=(Button) findViewById(R.id.btn_big);
    
    //SpannableString的ImageSpan添加左边图片
    SpannableString spannableString1=new SpannableString("left");
    ImageSpan imageSpan=new ImageSpan(this, BitmapFactory.decodeResource(getResources(), R.drawable.image_left));
    spannableString1.setSpan(imageSpan, 0, 4, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
    
    //SpannableString的ImageSpan添加右边图片
    SpannableString spannableString2=new SpannableString("right");
    ImageSpan imageSpan2=new ImageSpan(this, BitmapFactory.decodeResource(getResources(), R.drawable.image_right));
    spannableString2.setSpan(imageSpan2, 0, 5, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
    
    btn_big.append(spannableString1);
    btn_big.append("我的按钮");
    btn_big.append(spannableString2);
  }
}

<?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="match_parent"
  android:orientation="vertical"  
  
  <LinearLayout 
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
     
    
    <!--android:drawableTop="@drawable/star"实现文字上有图片 -- 
    <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="一" 
      android:drawableTop="@drawable/star"
      / 
    
    <!--android:drawablePadding="30dp实现文字和文字上的图片中间有30dp的空隙 -- 
    <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="二" 
      android:drawableTop="@drawable/star"
      android:drawablePadding="30dp"
      / 
    
    <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="三" 
      android:drawableRight="@drawable/star"
      / 
    
    <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="四" 
      android:drawableLeft="@drawable/star"
      / 
  </LinearLayout 
  
  <Button 
    android:id="@+id/btn_big"
    android:layout_width="180dp"
    android:layout_height="200dp"
    
    / 
  
</LinearLayout