分析：新建短信，当我们接受人RecipientsEditor中输入+86的时候，系统会自动在+86后加入空格

我们可以认为这是一个很人性的格式化操作，在ComposeMessageActivity中系统在调用initRecipientsEditor（）方法对联系人进行初始化的时候调用了 PhoneNumberFormatter.setPhoneNumberFormattingTextWatcher(this, mRecipientsEditor);我们通过对代码进行追踪发现，最终调用了Framework中PhoneNumberFormattingTextWatcher类对电话号码进行格式化处理，并在处理后在PhoneNumberFormatter中使用异步类控件的值进行处理，这里贴处该类的代码进行分析。

package android.telephony;



import com.android.i18n.phonenumbers.AsYouTypeFormatter;

import com.android.i18n.phonenumbers.PhoneNumberUtil;



import android.telephony.PhoneNumberUtils;

import android.text.Editable;

import android.text.Selection;

import android.text.TextWatcher;



import java.util.Locale;



/**

 * Watches a {@link android.widget.TextView} and if a phone number is entered

 * will format it.

 * <p>

 * Stop formatting when the user

 * <ul>

 * <li>Inputs non-dialable characters</li>

 * <li>Removes the separator in the middle of string.</li>

 * </ul>

 * <p>

 * The formatting will be restarted once the text is cleared.

 */

public class PhoneNumberFormattingTextWatcher implements TextWatcher {



    /**

     * Indicates the change was caused by ourselves.

     */

    private boolean mSelfChange = false;



    /**

     * Indicates the formatting has been stopped.

     */

    private boolean mStopFormatting;



    private AsYouTypeFormatter mFormatter;



    /**

     * The formatting is based on the current system locale and future locale changes

     * may not take effect on this instance.

     */

    public PhoneNumberFormattingTextWatcher() {

        this(Locale.getDefault().getCountry());

    }



    /**

     * The formatting is based on the given <code>countryCode</code>.

     *

     * @param countryCode the ISO 3166-1 two-letter country code that indicates the country/region

     * where the phone number is being entered.

     *

     * @hide

     */

    public PhoneNumberFormattingTextWatcher(String countryCode) {

        if (countryCode == null) throw new IllegalArgumentException();

        mFormatter = PhoneNumberUtil.getInstance().getAsYouTypeFormatter(countryCode);

    }



    @Override

    public void beforeTextChanged(CharSequence s, int start, int count,

            int after) {

        if (mSelfChange || mStopFormatting) {

            return;

        }

        // If the user manually deleted any non-dialable characters, stop formatting

        if (count > 0 && hasSeparator(s, start, count)) {

            stopFormatting();

        }

    }



    @Override

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

        if (mSelfChange || mStopFormatting) {

            return;

        }

        // If the user inserted any non-dialable characters, stop formatting

        if (count > 0 && hasSeparator(s, start, count)) {

            stopFormatting();

        }

    }



    @Override

    public synchronized void afterTextChanged(Editable s) {

        if (mStopFormatting) {

            // Restart the formatting when all texts were clear.

            mStopFormatting = !(s.length() == 0);

            return;

        }

        if (mSelfChange) {

            // Ignore the change caused by s.replace().

            return;

        }

        String formatted = reformat(s, Selection.getSelectionEnd(s));

        if (formatted != null) {

            int rememberedPos = mFormatter.getRememberedPosition();

            mSelfChange = true;

            s.replace(0, s.length(), formatted, 0, formatted.length());

            // The text could be changed by other TextWatcher after we changed it. If we found the

            // text is not the one we were expecting, just give up calling setSelection().

            if (formatted.equals(s.toString())) {

                Selection.setSelection(s, rememberedPos);

            }

            mSelfChange = false;

        }

    }



    /**

     * Generate the formatted number by ignoring all non-dialable chars and stick the cursor to the

     * nearest dialable char to the left. For instance, if the number is  (650) 123-45678 and '4' is

     * removed then the cursor should be behind '3' instead of '-'.

     */

    private String reformat(CharSequence s, int cursor) {

        // The index of char to the leftward of the cursor.

        int curIndex = cursor - 1;

        String formatted = null;

        mFormatter.clear();

        char lastNonSeparator = 0;

        boolean hasCursor = false;

        int len = s.length();

        for (int i = 0; i < len; i++) {

            char c = s.charAt(i);

            if (PhoneNumberUtils.isNonSeparator(c)) {

                if (lastNonSeparator != 0) {

                    formatted = getFormattedNumber(lastNonSeparator, hasCursor);

                    hasCursor = false;

                }

                lastNonSeparator = c;

            }

            if (i == curIndex) {

                hasCursor = true;

            }

        }

        if (lastNonSeparator != 0) {

            formatted = getFormattedNumber(lastNonSeparator, hasCursor);

        }

        return formatted;

    }



    private String getFormattedNumber(char lastNonSeparator, boolean hasCursor) {

        return hasCursor ? mFormatter.inputDigitAndRememberPosition(lastNonSeparator)

                : mFormatter.inputDigit(lastNonSeparator);

    }



    private void stopFormatting() {

        mStopFormatting = true;

        mFormatter.clear();

    }



    private boolean hasSeparator(final CharSequence s, final int start, final int count) {

        for (int i = start; i < start + count; i++) {

            char c = s.charAt(i);

            if (!PhoneNumberUtils.isNonSeparator(c)) {

                return true;

            }

        }

        return false;

    }

}

通过查看PhoneNumberFormattingTextWatcher代码我们发现，该类继承至TextWatcher，则实现了对RecipientEditor的值的变化进行了监听，最后调用PhoneNumberUtils进行处理。