[Android实例] 适应多行长文本的Android TextView

大家经常会用到系统默认的TextView，TextView可以很好地适应单行长文本(尾部自动打上省略号)，以及可以完整显示多行文本(TextView的宽高足够大)。但如果是很多行的文本而TextView又足够大的时候，则会出现以下这种情况.......超出的文本受TextView大小限制，不能完全显示。

本文主要实现一个能够适应多行长文本的TextView，自动缩减长文本并在结尾补上省略号。如下图：红色部分为普通的TextView，绿色部分为本文实现的TextView

 

本文的源码可以到 http://download.csdn.net/detail/hellogv/4298631 下载，本文的TextViewMultilineEllipse.java改自http://code.google.com/p/android-textview-multiline-ellipse/以及http://code.google.com/p/android/的MyClipTextView.java，相对于前面2者，本文使用哈希表来保存每次onMeasure()计算所得的宽高，大幅减少重复计算宽高。

本文的主Activity的源码如下：

public class AutoFixTextViewActivity extends Activity {
        private LinearLayout linearLayout1;
        private TextViewMultilineEllipse tvMultilineEllipse;
        private TextView tvNormal;

        //水调歌头，大家懂的
        private final String text= "明月几时有？把酒问青天。不知天上宫阙，今夕是何年。\n"
                        + "我欲乘风归去，又恐琼楼玉宇，高处不胜寒。\n"
                        + "起舞弄清影，何似在人间。\n"
                        + "转朱阁，低绮户，照无眠。不应有恨，何事长向别时圆？\n"
                        + "人有悲欢离合，月有阴晴圆缺，此事古难全。\n"
                        + "但愿人长久，千里共婵娟。" ;
   @Override
   public void onCreate(Bundle savedInstanceState) {
        super .onCreate(savedInstanceState);
        setContentView(R.layout.main);
        this .setTitle( "适应多行文本的Android TextView---hellogv" );

        //共同的宽高
        LayoutParams lp= new LayoutParams(LayoutParams.FILL_PARENT, 100 );
        //----用TextView来显示换行长文本----//
        tvNormal=(TextView) this .findViewById(R.id.tvNormal);
        tvNormal.setLayoutParams(lp); //限制TextView的宽高
        tvNormal.setEllipsize(TextUtils.TruncateAt.END);
        tvNormal.setSingleLine( false );
        tvNormal.setMaxLines( 5 );
        tvNormal.setText(text);


        //----用TextViewMultilineEllipse来显示换行长文本----//
        linearLayout1=(LinearLayout) this .findViewById(R.id.linearLayout1);

        tvMultilineEllipse = new TextViewMultilineEllipse( this );
               tvMultilineEllipse.setLayoutParams(lp); //限制TextView的宽高
               tvMultilineEllipse.setEllipsis( "..." ); //...替换剩余字符串
               tvMultilineEllipse.setMaxLines( 5 );
               tvMultilineEllipse.setTextSize(( int )tvNormal.getTextSize()); //设置文字大小
               tvMultilineEllipse.setTextColor(Color.WHITE);
               tvMultilineEllipse.setText(text); //设置文本

               //在代码里添加tvMultilineEllipse,暂时不支持Layout里直接添加
               linearLayout1.addView(tvMultilineEllipse);

   }


}

PS：TextViewMultilineEllipse是在代码里动态构建和使用，而不能直接在Layout.xml里使用。

main.xml的源码如下：

"1.0" encoding= "utf-8" ?>
"http://schemas.android.com/apk/res/android"
   android:layout_width= "fill_parent"
   android:layout_height= "fill_parent"
   android:orientation= "vertical" >


        android:id= "@+id/tvNormal"
        android:layout_width= "wrap_content"
        android:layout_height= "wrap_content"
        android:text= "Medium Text"
        android:textAppearance= "?android:attr/textAppearanceMedium" />


        android:id= "@+id/linearLayout1"
        android:layout_width= "match_parent"
        android:layout_height= "wrap_content"
        android:layout_marginTop= "20dip" >

TextViewMultilineEllipse.java源码如下，有点多，读者可以直接忽略：

public class TextViewMultilineEllipse extends TextView{

   private TextPaint mTextPaint;
   private String mText;
   private int mAscent;
   private String mStrEllipsis;
   private String mStrEllipsisMore;
   private int mMaxLines;
   private boolean mDrawEllipsizeMoreString;
   private int mColorEllipsizeMore;
   private boolean mRightAlignEllipsizeMoreString;
   private boolean mExpanded;
   private LineBreaker mBreakerExpanded;
   private LineBreaker mBreakerCollapsed;
   /**hashMapW是优化的关键点，通过哈希表来减少计算次数*/
   private HashMap hashMapW= new HashMap();
   public TextViewMultilineEllipse(Context context) {
        super (context);
     // TODO Auto-generated constructor stub
        mExpanded = false ;
        mDrawEllipsizeMoreString = true ;
        mRightAlignEllipsizeMoreString = false ;
        mMaxLines = - 1 ;
        mStrEllipsis = "..." ;
        mStrEllipsisMore = "" ;
        mColorEllipsizeMore = 0xFF0000FF ;

        mBreakerExpanded = new LineBreaker();
        mBreakerCollapsed = new LineBreaker();

        // Default font size and color.
        mTextPaint = new TextPaint();
        mTextPaint.setAntiAlias( true );
        mTextPaint.setTextSize( 13 );
        mTextPaint.setColor( 0xFF000000 );
        mTextPaint.setTextAlign(Align.LEFT);
        setDrawingCacheEnabled( true );
   }

   /**
     * Sets the text to display in this widget.
     * @param text The text to display.
     */
   public void setText(String text) {
        mText = text;
        requestLayout();
        invalidate();
   }

   /**
     * Sets the text size for this widget.
     * @param size Font size.
     */
   public void setTextSize( int size) {
        mTextPaint.setTextSize(size);
        requestLayout();
        invalidate();
   }

   /**
     * Sets the text color for this widget.
     * @param color ARGB value for the text.
     */
   public void setTextColor( int color) {
        mTextPaint.setColor(color);
        invalidate();
   }

   /**
     * The string to append when ellipsizing. Must be shorter than the available
     * width for a single line!
     * @param ellipsis The ellipsis string to use, like "...", or "-----".
     */
   public void setEllipsis(String ellipsis) {
        mStrEllipsis = ellipsis;
   }

   /**
     * Optional extra ellipsize string. This
     * @param ellipsisMore
     */
   public void setEllipsisMore(String ellipsisMore) {
        mStrEllipsisMore = ellipsisMore;
   }

   /**
     * The maximum number of lines to allow, height-wise.
     * @param maxLines
     */
   public void setMaxLines( int maxLines) {
        mMaxLines = maxLines;
   }

   /**
     * Turn drawing of the optional ellipsizeMore string on or off.
     * @param drawEllipsizeMoreString Yes or no.
     */
   public void setDrawEllipsizeMoreString( boolean drawEllipsizeMoreString) {
        mDrawEllipsizeMoreString = drawEllipsizeMoreString;
   }

   /**
     * Font color to use for the optional ellipsizeMore string.
     * @param color ARGB color.
     */
   public void setColorEllpsizeMore( int color) {
        mColorEllipsizeMore = color;
   }

   /**
     * When drawing the ellipsizeMore string, either draw it wherever ellipsizing on the last
     * line occurs, or always right align it. On by default.
     * @param rightAlignEllipsizeMoreString Yes or no.
     */
   public void setRightAlignEllipsizeMoreString( boolean rightAlignEllipsizeMoreString) {
        mRightAlignEllipsizeMoreString = rightAlignEllipsizeMoreString;
   }

   /**
     * @see android.view.View#measure(int, int)
     */
   @Override
   protected void onMeasure( int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(
            measureWidth(widthMeasureSpec),
            measureHeight(heightMeasureSpec));
   }

   /**
     * Determines the width of this view
     * @param measureSpec A measureSpec packed into an int
     * @return The width of the view, honoring constraints from measureSpec
     */
   private int measureWidth( int measureSpec) {
        int result = 0 ;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY) {
            // We were told how big to be.
            result = specSize;

            // Format the text using this exact width, and the current mode.
            breakWidth(specSize);
        }
        else {
            if (specMode == MeasureSpec.AT_MOST) {
               // Use the AT_MOST size - if we had very short text, we may need even less
               // than the AT_MOST value, so return the minimum.
               result = breakWidth(specSize);
               result = Math.min(result, specSize);
            }
            else {
               // We're not given any width - so in this case we assume we have an unlimited
               // width?
               breakWidth(specSize);
            }
        }

        return result;
   }

   /**
     * Determines the height of this view
     * @param measureSpec A measureSpec packed into an int
     * @return The height of the view, honoring constraints from measureSpec
     */
   private int measureHeight( int measureSpec) {
        int result = 0 ;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        mAscent = ( int ) mTextPaint.ascent();
        if (specMode == MeasureSpec.EXACTLY) {
            // We were told how big to be, so nothing to do.
            result = specSize;
        }
        else {
            // The lines should already be broken up. Calculate our max desired height
            // for our current mode.
            int numLines;
            if (mExpanded) {
               numLines = mBreakerExpanded.getLines().size();
            }
            else {
               numLines = mBreakerCollapsed.getLines().size();
            }
            result = numLines * ( int ) (-mAscent + mTextPaint.descent())
                  + getPaddingTop()
                  + getPaddingBottom();

            // Respect AT_MOST value if that was what is called for by measureSpec.
            if (specMode == MeasureSpec.AT_MOST) {
               result = Math.min(result, specSize);
            }
        }
        return result;
   }

   /**
     * Render the text
     *