Android富文本

1、SpannableString和SpannableStringBuilder

1、SpannableString和SpannableStringBuilder的区别相当于String和StringBuilder的区别,在Android中可以通过SpannableString或SpannableStringBuilder给存储的字符串添加样式,实现简单的富文本效果。
2、示例,类似朋友圈效果

  • 先看效果图:


    TIM截图20171016164750.png
  • 首先这是一段文字,小明和小红是蓝色,直接看下面代码:

    String content = "小明回复小红:一点状态都没有";
    mSpannableString = new SpannableString(content);
    mSpannableString.setSpan(new ForegroundColorSpan(Color.BLUE),0,2, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mSpannableString.setSpan(new ForegroundColorSpan(Color.BLUE),4,6, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mTextMessage.setText(mSpannableString);
    
  • 上面代码就实现了颜色效果,下面一步一步学习下
    首先,setSpan(Object what, int start, int end, int flags):

    参数一:表示样式,上面的ForegroundColorSpan就是一种样式,常用的样式如下:
    ForegroundColorSpan:为文本设置前景色;
    BackgroundColorSpan:为文本设置文本背景色;
    RelativeSizeSpan:为文本设置相对大小,在TextView原有的文字大小的基础上,相对设置文字大小;
    StrikethroughSpan:为文本设置中划线,也就是常说的删除线;
    UnderlineSpan:为文本设置下划线;
    SuperscriptSpan:为文本设置上标,可以配合RelativeSizeSpan做数学公式中的上标;
    SubscriptSpan:为文本设置下标;
    StyleSpan:为文本设置(粗体、斜体)风格;
    ImageSpan:将文本替换为图片;
    ClickableSpan:为文本设置点击事件;
    URLSpan:为文本设置超链接。

    参数二和三,start表示需要设置格式的子字符串的起始下标,end表示终止下标。

    参数四,flag表示子字符串是否包含开始或结束端点:
    Spanned.SPAN_EXCLUSIVE_EXCLUSIVE --- 不包含两端start和end所在的端点 --- (a,b);
    Spanned.SPAN_EXCLUSIVE_INCLUSIVE --- 不包含端start,但包含end所在的端点 --- (a,b];
    Spanned.SPAN_INCLUSIVE_EXCLUSIVE --- 包含两端start,但不包含end所在的端点 --- [a,b);
    Spanned.SPAN_INCLUSIVE_INCLUSIVE --- 包含两端start和end所在的端点 --- [a,b]。
    注意,flag只是在SpannableStringBuilder才有意义,如下:

    mSpannableStringBuilder.setSpan(new ForegroundColorSpan(Color.BLUE),0,2, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    mSpannableStringBuilder.setSpan(new ForegroundColorSpan(Color.BLUE),4,6, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    mSpannableStringBuilder.insert(2,"a");  //加入的a会根据flag来判断有没效果。
    
  • 到这里还有一步没有完成,就是小明和小红应该有点击效果,利用ClickableSpan:

    mSpannableString = new SpannableString(content);
    mSpannableString.setSpan(new ForegroundColorSpan(Color.BLUE),0,2, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mSpannableString.setSpan(new ForegroundColorSpan(Color.BLUE),4,6, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mSpannableString.setSpan(span,0,2,Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mTextMessage.setMovementMethod(LinkMovementMethod.getInstance());
    
    ClickableSpan span = new ClickableSpan() {
          @Override
          public void onClick(View widget) {
              String text = ((TextView) widget).getText().toString().substring(0,2);
              Toast.makeText(MainActivity.this,text,Toast.LENGTH_SHORT).show();
          }
    
         @Override
         public void updateDrawState(TextPaint ds) {
             super.updateDrawState(ds);
             ds.setUnderlineText(false); //去除下划线
         }
     };
    
  • 上面虽然实现了点击效果,但是需求是点击的时候背景为灰色,抬起又是原有的背景颜色,自己试了多个方法没成功,最后找到这个:

    public class LinkTouchMovementMethod extends LinkMovementMethod {
      private TouchableSpan mPressedSpan;
    
      @Override
      public boolean onTouchEvent(TextView textView, Spannable spannable, MotionEvent event) {
          if (event.getAction() == MotionEvent.ACTION_DOWN) {
              mPressedSpan = getPressedSpan(textView, spannable, event);
              if (mPressedSpan != null) {
                  mPressedSpan.setPressed(true);
                  Selection.setSelection(spannable, spannable.getSpanStart(mPressedSpan),
                          spannable.getSpanEnd(mPressedSpan));
              }
          } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
              TouchableSpan touchedSpan = getPressedSpan(textView, spannable, event);
              if (mPressedSpan != null && touchedSpan != mPressedSpan) {
                  mPressedSpan.setPressed(false);
                  mPressedSpan = null;
                  Selection.removeSelection(spannable);
              }
          } else {
              if (mPressedSpan != null) {
                  mPressedSpan.setPressed(false);
                  super.onTouchEvent(textView, spannable, event);
              }
              mPressedSpan = null;
              Selection.removeSelection(spannable);
          }
          return true;
      }
    
      private TouchableSpan getPressedSpan(TextView textView, Spannable spannable, MotionEvent event) {
    
          int x = (int) event.getX();
          int y = (int) event.getY();
    
          x -= textView.getTotalPaddingLeft();
          y -= textView.getTotalPaddingTop();
    
          x += textView.getScrollX();
          y += textView.getScrollY();
    
          Layout layout = textView.getLayout();
          int line = layout.getLineForVertical(y);
          int off = layout.getOffsetForHorizontal(line, x);
    
          TouchableSpan[] link = spannable.getSpans(off, off, TouchableSpan.class);
          TouchableSpan touchedSpan = null;
          if (link.length > 0) {
              touchedSpan = link[0];
          }
          return touchedSpan;
      }
    
    }
    
    
    public abstract class TouchableSpan extends ClickableSpan {
      private boolean mIsPressed;
      private int mPressedBackgroundColor;
      private int mNormalTextColor;
      private int mPressedTextColor;
    
      public TouchableSpan(int normalTextColor, int pressedTextColor, int pressedBackgroundColor) {
          mNormalTextColor = normalTextColor;
          mPressedTextColor = pressedTextColor;
          mPressedBackgroundColor = pressedBackgroundColor;
      }
    
      public void setPressed(boolean isSelected) {
          mIsPressed = isSelected;
      }
    
      @Override
      public void updateDrawState(TextPaint ds) {
          super.updateDrawState(ds);
          ds.setColor(mIsPressed ? mPressedTextColor : mNormalTextColor);
          ds.bgColor = mIsPressed ? mPressedBackgroundColor : Color.TRANSPARENT;
          ds.setUnderlineText(false);
      }
    }
    

    具体用法:

    mSpannableString = new SpannableString(content);
    mSpannableString.setSpan(new ForegroundColorSpan(Color.BLUE),0,2, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mSpannableString.setSpan(new ForegroundColorSpan(Color.BLUE),4,6, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mSpannableString.setSpan(span,0,2,Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    mTextMessage.setMovementMethod(new LinkTouchMovementMethod());
    
    TouchableSpan span = new TouchableSpan(Color.BLUE,Color.BLUE,Color.GRAY) {
          @Override
          public void onClick(View widget) {
              String text = ((TextView) widget).getText().toString().substring(0,2);
              Toast.makeText(MainActivity.this,text,Toast.LENGTH_SHORT).show();
          }
    
     };

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