# 3.3.2.Testing analyzers（测试分析器）

analyze API是查看分析器生成词语的一个非常有用的工具。内置的分析器（或结合内置的分词器，词语过滤器和字符过滤器）可以在请求中指定内联：

```
POST _analyze
{
  "analyzer": "whitespace",
  "text":     "The quick brown fox."}

POST _analyze
{
  "tokenizer": "standard",
  "filter":  [ "lowercase", "asciifolding" ],
  "text":      "Is this déja vu?"}
```

## Positions and character offsets（位置和字符偏移）

从analyze API的输出可以看出，分析器不仅将单词转换为词语，还记录了每个词语（用于短语查询或近义词查询）的顺序或相对位置，以及原始文本中每个词语的起始和结束字符的偏移量（用于突出搜索片段）。

或者，在特定的索引上运行analyze API时，可以参考自定义分析器：

```
PUT my_index
{
  "settings": {
    "analysis": {
      "analyzer": {
        "std_folded": {                       #1
          "type": "custom",
          "tokenizer": "standard",
          "filter": [
            "lowercase",
            "asciifolding"
          ]
        }
      }
    }
  },
  "mappings": {
    "my_type": {
      "properties": {
        "my_text": {
          "type": "text",
          "analyzer": "std_folded"            #2
        }
      }
    }
  }}

GET my_index/_analyze {                       #3
  "analyzer": "std_folded",                   #4
  "text":     "Is this déjà vu?"}

GET my_index/_analyze {                       #5
  "field": "my_text",                         #6
   "text":  "Is this déjà vu?"}
```

| 1   | 定义名为std\_folded的自定义分析器。      |
| --- | ---------------------------- |
| 2   | 字段my\_text使用std\_folded分析器。  |
| 3，5 | 要参考此分析器，analyze API必须指定索引名称。 |
| 4   | 按名称查看分析器。                    |
| 6   | 请参阅字段my\_text使用的分析器。         |


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