SpringBoot，Spring，Mysql数据库查出的数据，按拼音顺序排序分组的方法

废话不多说，上问题

如果你需要根据数据库的某个字段的首字母，按拼音顺序排序分组发给前端，那就找对了。

上代码

1.由于字段内容，有英文或者中文开头，直接排序不了，需要把中文变成拼音才能继续操作。

  <!-- 导入依赖 -->
 <dependency>
            <groupId>com.belerweb</groupId>
            <artifactId>pinyin4j</artifactId>
            <version>2.5.1</version>
 </dependency>

2.编写代码

 // 获取字符串的拼音字母
    private static String getPinyin(String input) {
        StringBuilder output = new StringBuilder();
        char[] chars = input.toCharArray();
        HanyuPinyinOutputFormat format = new HanyuPinyinOutputFormat();
        format.setCaseType(HanyuPinyinCaseType.UPPERCASE);
        format.setToneType(HanyuPinyinToneType.WITHOUT_TONE);

        for (char c : chars) {
            if (Character.isLetter(c)) {  // 判断字符是否为字母
                output.append(Character.toLowerCase(c));
            } else if (isChinese(c)) {  // 判断字符是否为中文
                String[] pinyinArray = new String[0];
                try {
                    pinyinArray = PinyinHelper.toHanyuPinyinStringArray(c, format);
                } catch (BadHanyuPinyinOutputFormatCombination e) {
                    e.printStackTrace();
                }
                if (pinyinArray == null) {
                    output.append(c);
                } else {
                    output.append(pinyinArray[0].charAt(0));
                }
            }
        }

        return output.toString();
    }

    /**
     * @param key      按这个字段拼音，排序分组
     * @param arrayMap {@link List}<{@link HashMap}<{@link String}, {@link Object}>>
     * @return {@link Map}<{@link String}, {@link List}<{@link HashMap}<{@link String}, {@link Object}>>>
     * @apiNote 按拼音顺序排列分组，字符串的第一个文字无论是中文还是英文，不影响排序结果，<p>应用场景: </p><p>通讯录，好友列表，A-Z。</p>
     * @since 2023-10-17
     **/
    private static Map<String, List<HashMap<String, Object>>> GroupedInPinyinOrder(ArrayList<HashMap<String, Object>> arrayMap, String key) {
        // 创建自定义的Comparator
        Comparator<HashMap<String, Object>> comparator = (hashMap, hashMap2) -> {
            String name = (String) hashMap.get(key);
            String name2 = (String) hashMap2.get(key);
            // 比较首字母或拼音
            String pinyin = getPinyin(name);
            String pinyin2 = getPinyin(name2);
            return pinyin.compareTo(pinyin2);
        };
        //按拼音顺序排序A-Z
        arrayMap.sort(comparator);
        //按拼音顺序分组A-Z
        HanyuPinyinOutputFormat format = new HanyuPinyinOutputFormat();
        format.setCaseType(HanyuPinyinCaseType.UPPERCASE);
        format.setToneType(HanyuPinyinToneType.WITHOUT_TONE);
        Map<String, List<HashMap<String, Object>>> groupedData = new TreeMap<>();
        for (HashMap<String, Object> data : arrayMap) {
            String name = (String) data.get(key);
            //作为groupedData的key
            String pinyin = String.valueOf(getPinyin(name).charAt(0)).toUpperCase();
            char c = pinyin.toLowerCase().toCharArray()[0];
            try {
                //如果首字符为中文，则转换成拼音取首字母
                if (isChinese(c)) {
                    pinyin = String.valueOf(PinyinHelper.toHanyuPinyinStringArray(c, format)[0].toUpperCase().charAt(0));
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            List<HashMap<String, Object>> group = groupedData.computeIfAbsent(pinyin, k -> new ArrayList<>());
            group.add(data);
        }
        return groupedData;
    }

    private static boolean isChinese(char c) {
        Character.UnicodeBlock block = Character.UnicodeBlock.of(c);
        return block == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS ||
                block == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS ||
                block == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A ||
                block == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_B ||
                block == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION ||
                block == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS ||
                block == Character.UnicodeBlock.GENERAL_PUNCTUATION;
    }

3.测试数据

 ArrayList<HashMap<String, Object>> arrayMap = new ArrayList<>();
        list.forEach((elem -> {
            HashMap<String, Object> hashMap = new HashMap<>();
            User user = userService.getById(elem.getUserId());
            hashMap.put("id", elem.getToId());
            hashMap.put("avatar", user.getAvatar());
            hashMap.put("name", elem.getToNotes());
            arrayMap.add(hashMap);
        }));

4.测试与结果

   System.out.println(GroupedInPinyinOrder(arrayMap, "name").toString());

5.总结
如果直接用数据库查出来，不用Map，可用实体对象，其思路是一致的，稍微改一下即可，如果对你有用，欢迎一键三联。