Android at人功能 -- MentionEditText

   <h2><strong>前言</strong></h2>    <p>这个功能看似简单，网上搜出来的都说以@+uid+空格这样的格式处理，但实际实现会发现有个问题：如果用户名之间有空格，那么就无法正确解析出要@的用户了，而且如果有同名用户，也无法区分。因此若要以这样简单的方式处理，那么对用户名就需要一个复杂的限制，显然现在去修改早已定下的规则是不现实的。</p>    <p>根据业务需求，作了比较大的改动，大致如下：</p>    <ul>     <li> <p>只能通过mentionUser这个方法增加mention string</p> </li>     <li> <p>简化了对输入的监视</p> </li>     <li> <p>完善了对range的管理</p> </li>     <li> <p>通过convertMention的方法，将@uid转换为指定格式的字符串并返回</p> </li>    </ul>    <h2><strong>QQ和微信@人功能对比</strong></h2>    <p>QQ:@之后弹出用户选择界面，选择用户后输出“@用户名 ”格式，无法在@与用户名之间插入任何字符，删除时是整个删除</p>    <p>微信：@之后弹出用户选择界面，选择用户后输出“@用户名 ”格式，可以在@与用户名之间插入字符，删除时也是作为整个删除</p>    <h2><strong>实现原理：</strong></h2>    <p>在调用mentionUser之后，会在光标所在位置插入@username的span，并且创建一个range保存到arraylist中，该range会记录所插入span的起始、终止位置还有插入的用户信息。</p>    <p>luckyandyzhang的实现是在每一次textchanged后都会扫描整个字符串，生成对应的span。</p>    <h2><strong>代码</strong></h2>    <pre>  <code class="language-java">private final String mMentionTextFormat = "[Mention:%s, %s]";      private Runnable mAction;        private int mMentionTextColor;        private boolean mIsSelected;      private Range mLastSelectedRange;      private ArrayList<Range> mRangeArrayList;        private OnMentionInputListener mOnMentionInputListener;        public MentionEditText(Context context) {          super(context);          init();      }        public MentionEditText(Context context, AttributeSet attrs) {          super(context, attrs);          init();      }        public MentionEditText(Context context, AttributeSet attrs, int defStyleAttr) {          super(context, attrs, defStyleAttr);          init();      }        @Override      public InputConnection onCreateInputConnection(EditorInfo outAttrs) {          return new HackInputConnection(super.onCreateInputConnection(outAttrs), true, this);      }        @Override      public void setText(final CharSequence text, TextView.BufferType type) {          super.setText(text, type);          //hack, put the cursor at the end of text after calling setText() method          if (mAction == null) {              mAction = new Runnable() {                  @Override                  public void run() {                      setSelection(getText().length());                  }              };          }          post(mAction);      }        @Override      protected void onSelectionChanged(int selStart, int selEnd) {          super.onSelectionChanged(selStart, selEnd);          //avoid infinite recursion after calling setSelection()          if (mLastSelectedRange != null && mLastSelectedRange.isEqual(selStart, selEnd)) {              return;          }            //if user cancel a selection of mention string, reset the state of 'mIsSelected'          Range closestRange = getRangeOfClosestMentionString(selStart, selEnd);          if (closestRange != null && closestRange.to == selEnd) {              mIsSelected = false;          }            Range nearbyRange = getRangeOfNearbyMentionString(selStart, selEnd);          //if there is no mention string nearby the cursor, just skip          if (nearbyRange == null) {              return;          }            //forbid cursor located in the mention string.          if (selStart == selEnd) {              setSelection(nearbyRange.getAnchorPosition(selStart));          } else {              if (selEnd < nearbyRange.to) {                  setSelection(selStart, nearbyRange.to);              }              if (selStart > nearbyRange.from) {                  setSelection(nearbyRange.from, selEnd);              }          }      }        /**       * set highlight color of mention string       *       * @param color value from 'getResources().getColor()' or 'Color.parseColor()' etc.       */      public void setMentionTextColor(int color) {          mMentionTextColor = color;      }        /**       * 插入mention string       * 在调用该方法前，请先插入一个字符（如'@'），之后插入的name将会和该字符组成一个整体       * @param uid 用户id       * @param name 用户名字       */      public void mentionUser(int uid, String name) {          Editable editable = getText();          int start = getSelectionStart();          int end = start + name.length();          editable.insert(start, name);          editable.setSpan(new ForegroundColorSpan(mMentionTextColor), start - 1, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);          mRangeArrayList.add(new Range(uid, name, start - 1, end));      }        /**       * 将所有mention string以指定格式输出       * @return 以指定格式输出的字符串       */      public String convertMetionString() {          String text = getText().toString();          if (mRangeArrayList.isEmpty()) {              return text;          }            StringBuilder builder = new StringBuilder("");          int lastRangeTo = 0;          Collections.sort(mRangeArrayList);            for (Range range : mRangeArrayList) {              String newChar = String.format(mMentionTextFormat, range.id, range.name);              builder.append(text.substring(lastRangeTo, range.from));              builder.append(newChar);              lastRangeTo = range.to;          }            clear();          return builder.toString();      }        public void clear() {          mRangeArrayList.clear();          setText("");      }        /**       * set listener for mention character('@')       *       * @param onMentionInputListener MentionEditText.OnMentionInputListener       */      public void setOnMentionInputListener(OnMentionInputListener onMentionInputListener) {          mOnMentionInputListener = onMentionInputListener;      }        private void init() {          mRangeArrayList = new ArrayList<>();          mMentionTextColor = Color.RED;          //disable suggestion          setInputType(InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS);          addTextChangedListener(new MentionTextWatcher());      }        private Range getRangeOfClosestMentionString(int selStart, int selEnd) {          if (mRangeArrayList == null) {              return null;          }          for (Range range : mRangeArrayList) {              if (range.contains(selStart, selEnd)) {                  return range;              }          }          return null;      }        private Range getRangeOfNearbyMentionString(int selStart, int selEnd) {          if (mRangeArrayList == null) {              return null;          }          for (Range range : mRangeArrayList) {              if (range.isWrappedBy(selStart, selEnd)) {                  return range;              }          }          return null;      }        private class MentionTextWatcher implements TextWatcher {          //若从整串string中间插入字符，需要将插入位置后面的range相应地挪位          @Override          public void beforeTextChanged(CharSequence s, int start, int count, int after) {              Editable editable = getText();              //在末尾增加就不需要处理了              if (start >= editable.length()) {                  return;              }                int end = start + count;              int offset = after - count;                //清理start 到 start + count之间的span              //如果range.from = 0，也会被getSpans(0,0,ForegroundColorSpan.class)获取到              if (start != end && !mRangeArrayList.isEmpty()) {                  ForegroundColorSpan[] spans = editable.getSpans(start, end, ForegroundColorSpan.class);                  for (ForegroundColorSpan span : spans) {                      editable.removeSpan(span);                  }              }                //清理arraylist中上面已经清理掉的range              //将end之后的span往后挪offset个位置              Iterator iterator = mRangeArrayList.iterator();              while (iterator.hasNext()) {                  Range range = (Range) iterator.next();                  if (range.isWrapped(start, end)) {                      iterator.remove();                      continue;                  }                    if (range.from >= end) {                      range.setOffset(offset);                  }              }          }            @Override          public void onTextChanged(CharSequence charSequence, int index, int i1, int count) {              if (count == 1 && !TextUtils.isEmpty(charSequence)) {                  char mentionChar = charSequence.toString().charAt(index);                  if ('@' == mentionChar && mOnMentionInputListener != null) {                      mOnMentionInputListener.onMentionCharacterInput();                  }              }          }            @Override          public void afterTextChanged(Editable editable) {          }      }        //handle the deletion action for mention string, such as '@test'      private class HackInputConnection extends InputConnectionWrapper {          private EditText editText;            private HackInputConnection(InputConnection target, boolean mutable, MentionEditText editText) {              super(target, mutable);              this.editText = editText;          }            @Override          public boolean sendKeyEvent(KeyEvent event) {              if (event.getAction() == KeyEvent.ACTION_DOWN && event.getKeyCode() == KeyEvent.KEYCODE_DEL) {                  int selectionStart = editText.getSelectionStart();                  int selectionEnd = editText.getSelectionEnd();                  Range closestRange = getRangeOfClosestMentionString(selectionStart, selectionEnd);                  if (closestRange == null) {                      mIsSelected = false;                      return super.sendKeyEvent(event);                  }                  //if mention string has been selected or the cursor is at the beginning of mention string, just use default action(delete)                  if (mIsSelected || selectionStart == closestRange.from) {                      mIsSelected = false;                      return super.sendKeyEvent(event);                  } else {                      //select the mention string                      mIsSelected = true;                      mLastSelectedRange = closestRange;                      setSelection(closestRange.to, closestRange.from);                  }                  return true;              }              return super.sendKeyEvent(event);          }            @Override          public boolean deleteSurroundingText(int beforeLength, int afterLength) {              if (beforeLength == 1 && afterLength == 0) {                  return sendKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL))                          && sendKeyEvent(new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_DEL));              }              return super.deleteSurroundingText(beforeLength, afterLength);          }      }        //helper class to record the position of mention string in EditText      private class Range implements Comparable{          int id;          String name;          int from;          int to;            private Range(int id, String name, int from, int to) {              this.id = id;              this.name = name;              this.from = from;              this.to = to;          }            private boolean isWrapped(int start, int end) {              return from >= start && to <= end;          }            private boolean isWrappedBy(int start, int end) {              return (start > from && start < to) || (end > from && end < to);          }            private boolean contains(int start, int end) {              return from <= start && to >= end;          }            private boolean isEqual(int start, int end) {              return (from == start && to == end) || (from == end && to == start);          }            private int getAnchorPosition(int value) {              if ((value - from) - (to - value) >= 0) {                  return to;              } else {                  return from;              }          }            private void setOffset(int offset) {              from += offset;              to += offset;          }           @Override          public int compareTo(@NonNull Object o) {              return from - ((Range)o).from;          }      }          /**       * Listener for '@' character       */      public interface OnMentionInputListener {          /**           * call when '@' character is inserted into EditText           */          void onMentionCharacterInput();      }</code></pre>    <p> </p>    <p>来自：https://segmentfault.com/a/1190000007195099</p>    <p> </p>