实践中的重构01_一段代码的细调

重构的概念已经为广大的程序员所熟悉。但是还是有很多细节可以注意。
    public static String getHiddenEmail(String email, int prefix, int suffix) {
        // 仅对包含@的email账户进行处理
        if (StringUtil.isBlank(email) || !StringUtil.contains(email, "@")) {
            return email;
        }

        int length = email.length();

        if (length < DEFAULT_TOTAL) {
            return email;
        }
        // @所在位置
        int splitPos = StringUtil.lastIndexOf(email, '@');
        // @前的字符段
        String preEmail = StringUtil.substring(email, 0, splitPos);
        if (StringUtil.isBlank(preEmail)) {
            return email;
        }
        // @后的字符段,包含@
        String latEmail = StringUtil.substring(email, splitPos, length);
        if (StringUtil.isBlank(latEmail)) {
            return email;
        }
        if (preEmail.length() > 17)
            preEmail = StringUtil.abbreviate(preEmail, prefix);

        if (latEmail.length() > 13)
            latEmail = StringUtil.abbreviate(latEmail, suffix);

        return preEmail.concat(latEmail);
    }

以上的code在我看来,有以下几个缺点。
1 方法名和实际的方法体不匹配。
2 魔数
3 if (StringUtil.isBlank(latEmail)) 永远返回false,因为当程序执行到这里,latEmail至少包括一个字符@。
4 方法中的代码的内聚性不够。主要是对preEmail和latEmail的处理分开了。
5 拼写错误,应该为lastEmail而误拼为latEmail

清洗代码后如下
private static String getAbbreviatedEmail(String email, int prefix, int suffix) {

        if (StringUtil.isBlank(email)) {
            return email;
        }

        if (email.length() <= DEFAULT_TOTAL) {
            return email;
        }

        // @所在位置
        int splitPos = StringUtil.lastIndexOf(email, '@');
        if (splitPos == -1 || splitPos == 0|| splitPos == email.length() - 1) {
            return email;
        }

        // @前的字符段
        String preEmail = StringUtil.substring(email, 0, splitPos);
        if (preEmail.length() > DEFAULT_PREFIX_LENGTH) {
            preEmail = StringUtil.abbreviate(preEmail, prefix);
        }

        // @后的字符段,包含@
        String lastEmail = StringUtil.substring(email, splitPos, email.length());
        if (lastEmail.length() > DEFAULT_SUFFIX_LENGTH) {
            lastEmail = StringUtil.abbreviate(lastEmail , suffix);
        }

        return preEmail+lastEmail ;
    }


其实我个人最喜欢的风格是简单的方法的guard condition不用大括号{},这样代码变为

private static String getAbbreviatedEmail(String email, int prefix, int suffix) {

        if (StringUtil.isBlank(email)) 
            return email;

        if (email.length() <= DEFAULT_TOTAL) 
            return email;

        // @所在位置
        int splitPos = StringUtil.lastIndexOf(email, '@');
        if (splitPos == -1 || splitPos == 0|| splitPos == email.length() - 1) 
            return email;

        // @前的字符段
        String preEmail = StringUtil.substring(email, 0, splitPos);
        if (preEmail.length() > DEFAULT_PREFIX_LENGTH) {
            preEmail = StringUtil.abbreviate(preEmail, prefix);
        }

        // @后的字符段,包含@
        String lastEmail = StringUtil.substring(email, splitPos, email.length());
        if (lastEmail.length() > DEFAULT_SUFFIX_LENGTH) {
            lastEmail = StringUtil.abbreviate(lastEmail , suffix);
        }

        return preEmail+lastEmail ;
    }


谢谢论坛上朋友的讨论,preEmail+latEmail这个地方用+号比用concat方法好。

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