Android自定义View实现打字机效果

所属分类：软件编程 / Android 阅读数： 32

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一、先来看看效果演示

二、实现原理：

这个其实不难实现，通过一个定时器不断调用TextView的setText就行了，在setText的时候播放打字的音效。

具体代码如下：

import java.util.Timer;
import java.util.TimerTask;

import android.content.Context;
import android.media.MediaPlayer;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.widget.TextView;

import com.uperone.typetextview.R;

/**
 * 模拟打字机效果
 * 
 * */
public class TypeTextView extends TextView {
 private Context mContext = null;
 private MediaPlayer mMediaPlayer = null;
 private String mShowTextString = null;
 private Timer mTypeTimer = null;
 private OnTypeViewListener mOnTypeViewListener = null;
 private static final int TYPE_TIME_DELAY = 80;
 private int mTypeTimeDelay = TYPE_TIME_DELAY; // 打字间隔

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

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

 public TypeTextView(Context context) {
  super(context);
  initTypeTextView( context );
 }

 public void setOnTypeViewListener( OnTypeViewListener onTypeViewListener ){
  mOnTypeViewListener = onTypeViewListener;
 }

 public void start( final String textString ){
  start( textString, TYPE_TIME_DELAY );
 }

 public void start( final String textString, final int typeTimeDelay ){
  if( TextUtils.isEmpty( textString ) || typeTimeDelay < 0 ){
   return;
  }
  post( new Runnable( ) {
   @Override
   public void run() {
    mShowTextString = textString;
    mTypeTimeDelay = typeTimeDelay;
    setText( "" );
    startTypeTimer( );
    if( null != mOnTypeViewListener ){
     mOnTypeViewListener.onTypeStart( );
    }
   }
  });
 }

 public void stop( ){
  stopTypeTimer( );
  stopAudio();
 }

 private void initTypeTextView( Context context ){
  mContext = context;
 }

 private void startTypeTimer( ){
  stopTypeTimer( );
  mTypeTimer = new Timer( );
  mTypeTimer.schedule( new TypeTimerTask(), mTypeTimeDelay );
 }

 private void stopTypeTimer( ){
  if( null != mTypeTimer ){
   mTypeTimer.cancel( );
   mTypeTimer = null;
  }
 }

 private void startAudioPlayer() {
  stopAudio();
  playAudio( R.raw.type_in );
 }

 private void playAudio( int audioResId ){
  try{
   stopAudio( );
   mMediaPlayer = MediaPlayer.create( mContext, audioResId );
   mMediaPlayer.start( );
  }catch( Exception e ){
   e.printStackTrace();
  }
 }

 private void stopAudio( ){
  if( mMediaPlayer != null && mMediaPlayer.isPlaying( ) ){
   mMediaPlayer.stop( );
   mMediaPlayer.release( );
   mMediaPlayer = null;
  }
 }

 class TypeTimerTask extends TimerTask{
  @Override
  public void run() {
   post(new Runnable( ) {
    @Override
    public void run() {
     if( getText( ).toString( ).length( ) < mShowTextString.length( ) ){
      setText( mShowTextString.substring(0, getText( ).toString( ).length( ) + 1 ) );
      startAudioPlayer();
      startTypeTimer( );
     }else{
      stopTypeTimer( );
      if( null != mOnTypeViewListener ){
       mOnTypeViewListener.onTypeOver( );
      }
     }
    }
   });
  }
 }

 public interface OnTypeViewListener{
  public void onTypeStart( );
  public void onTypeOver( );
 }
}

三、使用说明：

1、在xml文件中定义：

 <com.uperone.typetext.view.TypeTextView
  android:id="@+id/typeTxtId"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:layout_centerVertical="true" />

2、在代码中实例化：

 mTypeTextView = ( TypeTextView )findViewById(R.id.typeTxtId);
 mTypeTextView.setOnTypeViewListener( new OnTypeViewListener( ) {
  @Override
  public void onTypeStart() {
   print( "onTypeStart" );
  }

  @Override
  public void onTypeOver() {
   print( "onTypeOver" );
  }
 });

3、调用start方法：