1.需求：
现在有个原始文本："电阻@CAL-CHIP@55@55w@±1%@330Ω@1/8W@55℃@xiaolong(电脑)@3000HF"，如果使用官方分词器，分词之后的结果如下：
{"tokens": [{"token": "电","start_offset": 0,"end_offset": 1,"type": "<IDEOGRAPHIC>","position": 0},{"token": "阻","start_offset": 1,"end_offset": 2,"type": "<IDEOGRAPHIC>","position": 1},{"token": "cal","start_offset": 3,"end_offset": 6,"type": "<ALPHANUM>","position": 2},{"token": "chip","start_offset": 7,"end_offset": 11,"type": "<ALPHANUM>","position": 3},{"token": "55","start_offset": 12,"end_offset": 14,"type": "<NUM>","position": 4},{"token": "55w","start_offset": 15,"end_offset": 18,"type": "<ALPHANUM>","position": 5},{"token": "1","start_offset": 20,"end_offset": 21,"type": "<NUM>","position": 6},{"token": "330ω","start_offset": 23,"end_offset": 27,"type": "<ALPHANUM>","position": 7},{"token": "1","start_offset": 28,"end_offset": 29,"type": "<NUM>","position": 8},{"token": "8w","start_offset": 30,"end_offset": 32,"type": "<ALPHANUM>","position": 9},{"token": "55","start_offset": 33,"end_offset": 35,"type": "<NUM>","position": 10},{"token": "xiaolong","start_offset": 37,"end_offset": 45,"type": "<ALPHANUM>","position": 11},{"token": "电","start_offset": 46,"end_offset": 47,"type": "<IDEOGRAPHIC>","position": 12},{"token": "脑","start_offset": 47,"end_offset": 48,"type": "<IDEOGRAPHIC>","position": 13},{"token": "3000hf","start_offset": 50,"end_offset": 56,"type": "<ALPHANUM>","position": 14}]
}可以看到，这个分词之后的结果是以：@，-，±，%，/，℃ 这些符号为界限把词给分开，并且遇到中文的时候，分词的结果是要逐字分词，现在我需要实现的效果是：原来分词的效果不变，只是不能把 ℃ 这个符号给去掉，也就是说理想的结果是这样的：
........
{"token": "8w","start_offset": 30,"end_offset": 32,"type": "<ALPHANUM>","position": 9},{"token": "55℃","start_offset": 33,"end_offset": 35,"type": "<NUM>","position": 10},{"token": "xiaolong","start_offset": 37,"end_offset": 45,"type": "<ALPHANUM>","position": 11},
.....2.通过自定义分词器来实现：
{"settings": {"analysis": {"analyzer": {"custom_analyzer": {"type": "custom","tokenizer": "combined_tokenizer","char_filter": ["chinese_space_char_filter"]}},"tokenizer": {"combined_tokenizer": {"type": "pattern","pattern": ["-|@|,|!|?|=|/|±| |(|)|?"]}},"char_filter": {"chinese_space_char_filter": {"type": "pattern_replace","pattern": "([\\u4e00-\\u9fa5])","replacement": " $1 "}}}},"mappings": {"properties": {"parameterSplicing": {"type": "text","analyzer": "custom_analyzer","index": true,"store": false}}}}通过这个来作为分词器，然后分词效果如下：
{"analyzer": "custom_analyzer","text": "电阻@CAL-CHIP@55@55w@±1%@330Ω@1/8W@55℃@xiaolong(小龙牌电脑)@3000HF"
}分词结果：
{"tokens": [{"token": "电","start_offset": 0,"end_offset": 0,"type": "word","position": 0},{"token": "阻","start_offset": 1,"end_offset": 1,"type": "word","position": 1},{"token": "CAL","start_offset": 3,"end_offset": 6,"type": "word","position": 2},{"token": "CHIP","start_offset": 7,"end_offset": 11,"type": "word","position": 3},{"token": "55","start_offset": 12,"end_offset": 14,"type": "word","position": 4},{"token": "55w","start_offset": 15,"end_offset": 18,"type": "word","position": 5},{"token": "1%","start_offset": 20,"end_offset": 22,"type": "word","position": 6},{"token": "330Ω","start_offset": 23,"end_offset": 27,"type": "word","position": 7},{"token": "1","start_offset": 28,"end_offset": 29,"type": "word","position": 8},{"token": "8W","start_offset": 30,"end_offset": 32,"type": "word","position": 9},{"token": "55℃","start_offset": 33,"end_offset": 36,"type": "word","position": 10},{"token": "xiaolong","start_offset": 37,"end_offset": 45,"type": "word","position": 11},{"token": "小","start_offset": 46,"end_offset": 46,"type": "word","position": 12},{"token": "龙","start_offset": 47,"end_offset": 47,"type": "word","position": 13},{"token": "牌","start_offset": 48,"end_offset": 48,"type": "word","position": 14},{"token": "电","start_offset": 49,"end_offset": 49,"type": "word","position": 15},{"token": "脑","start_offset": 50,"end_offset": 50,"type": "word","position": 16},{"token": "3000HF","start_offset": 53,"end_offset": 59,"type": "word","position": 17}]
}可以看到，这个 55℃ 被完整的保留下来了，
3.解释：
1.
settings部分
analysis节点：这是整个分析器相关配置的核心节点，用于定义各种分析组件，像分析器（analyzer）、分词器（tokenizer）以及字符过滤器（char_filter）等。
analyzer节点（自定义分析器定义）：
custom_analyzer：这是自定义的一个分析器名称，它的类型被指定为custom，意味着需要自行组合各种组件（分词器、字符过滤器等）来构建其功能。- 组件配置：它使用了名为
combined_tokenizer的分词器，并且关联了一个名为chinese_space_char_filter的字符过滤器。通过这样的搭配，文本在经过这个分析器处理时，会先由combined_tokenizer进行初步的分词操作，然后再经过chinese_space_char_filter做进一步的文本处理（后文会详细介绍具体处理内容）。tokenizer节点（分词器定义）：
combined_tokenizer：具体定义了一个名为combined_tokenizer的分词器，其类型是pattern，也就是基于正则表达式模式来进行分词操作。pattern配置：其pattern属性值为-|@|,|!|?|=|/|±| |(|)|?，这是一个正则表达式模式，含义是以 “或” 的关系罗列了一系列用于分词的标识符号。具体来说，文本中一旦出现-、@、，、!、?、=、/、±、空格、(、)这些符号中的任意一个，分词器就会在该符号出现的位置将文本分割成不同的词项。例如，对于文本"电阻@CAL-CHIP@0805@±1%@330Ω@1/8W@55℃"，就会依据这些符号进行相应的拆分，像根据@把各个不同部分拆分开等。char_filter节点（字符过滤器定义）：
chinese_space_char_filter：定义了一个字符过滤器，类型为pattern_replace，主要用于对文本中的中文字符进行特定处理。pattern和replacement配置：pattern属性值为([\\u4e00-\\u9fa5])，这是利用 Unicode 编码范围来匹配任意单个中文字符，并且使用括号进行了分组捕获；replacement属性值为$1，表示将匹配到的单个中文字符（也就是前面分组捕获的内容）前后都添加一个空格。这样做的目的是在分词之后，对于文本里出现的中文部分，每个中文字符都能以添加前后空格的形式存在，方便后续可能的进一步文本处理或者索引、查询匹配等操作，使其在文本结构上更清晰、便于区分。
在这里需要重点说明一下，之所以遇到中文可以逐字分词，那是因为通过字符过滤器，在分词之前把中文的每一个字前后都加上了空格，然后在分词器里面有定义：遇到空格就进行分词，所以就可以做到分词之后的效果是逐字分词