在Android Java中键入时在Edittext中自动着色标签

import android.content.Context;
import android.graphics.Color;
import android.text.Editable;
import android.text.Spannable;
import android.text.SpannableStringBuilder;
import android.text.TextWatcher;
import android.text.style.ForegroundColorSpan;
import android.util.AttributeSet;
import android.widget.EditText;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class TagEditText extends EditText {

    private static final String TAG_PATTERN = "#\\w+"; // 标签的正则表达式

    public TagEditText(Context context) {
        super(context);
        init();
    }

    public TagEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public TagEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
            }

            @Override
            public void afterTextChanged(Editable s) {
                highlightTags(s);
            }
        });
    }

    private void highlightTags(Editable editable) {
        SpannableStringBuilder spannable = new SpannableStringBuilder(editable);
        Pattern pattern = Pattern.compile(TAG_PATTERN);
        Matcher matcher = pattern.matcher(editable);

        while (matcher.find()) {
            int start = matcher.start();
            int end = matcher.end();
            spannable.setSpan(new ForegroundColorSpan(Color.BLUE), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        }

        setText(spannable);
        setSelection(editable.length());
    }
}