Android实现可以展开的TextView

本文实例为大家分享了一个可以展开的TextView的具体代码，供大家参考，具体内容如下

原理是通过点击的时候设置 setMaxLines(lineNum)来实现:

public class ExpandableTextView extends TextView { 
 private static int MIN_LINE_NUM = 2; 
 private static int MAX_LINE_NUM = 20; 
 private int lineNum = MIN_LINE_NUM; 
 private boolean mIsExpanded = false; 
 Bitmap bitmapDown; 
 Bitmap bitmapUp; 
 int w, h; 
  
 private onClickListener mOnClickListener; 
 
 public ExpandableTextView(Context context, AttributeSet attrs) { 
  super(context, attrs); 
  init(context, attrs); 
 } 
 
 private void init(Context context, AttributeSet attrs) { 
  setMaxLines(lineNum); 
  bitmapDown = BitmapFactory.decodeResource(getResources(), R.drawable.update_detail_down); 
  bitmapUp = BitmapFactory.decodeResource(getResources(), R.drawable.update_detail_up); 
  w = bitmapDown.getWidth() + (int) context.getResources().getDimension(R.dimen.expand_textview_right); 
  h = bitmapDown.getHeight() + (int) context.getResources().getDimension(R.dimen.expand_textview_bottom); 
   
  super.setonClickListener(new onClickListener() { 
   @Override 
   public void onClick(View v) { 
    if (lineNum == MIN_LINE_NUM) { 
     lineNum = MAX_LINE_NUM; 
     setMaxLines(lineNum); 
    } else { 
     lineNum = MIN_LINE_NUM; 
     setMaxLines(lineNum); 
    } 
    if (monClickListener != null) { 
     mOnClickListener.onClick(v); 
    } 
   } 
  }); 
 } 
 
 @Override 
 public void setonClickListener(onClickListener listener) { 
  if (!isClickable()) { 
   setClickable(true); 
  } 
  monClickListener = listener; 
 } 
 
 @Override 
 public void setMaxLines(int maxlines) { 
  super.setMaxLines(maxlines); 
 
  if (lineNum == MAX_LINE_NUM) { 
   mIsExpanded = true; 
  } else { 
   mIsExpanded = false; 
  } 
 } 
 
 public boolean isExpanded() { 
  return mIsExpanded; 
 } 
 
 @Override 
 protected void onDraw(Canvas canvas) { 
  if (getLineCount() <= MIN_LINE_NUM) { 
   super.onDraw(canvas); 
   return; 
  } 
  if (lineNum == MIN_LINE_NUM) { 
   canvas.drawBitmap(bitmapDown, getWidth() - w, getHeight() - h, null); 
  } else { 
   canvas.drawBitmap(bitmapUp, getWidth() - w, getHeight() - h, null); 
  } 
  super.onDraw(canvas); 
 } 
 
 
 public void setMaxLine(int line) { 
  lineNum = line; 
  setMaxLines(line); 
 } 
} 

这样来写Layout:

效果图：

代码：一个可以展开的TextView

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。