Jackson YAML:使用标志映射正则表达式模式

2022-01-14 00:00:00 regex yaml java jackson

在 Jackson 中，我可以映射 YAML 中的字符串:

In Jackson, I can map a string in YAML:

regexField: "(\d{2}):(\d{2})"

到类上的 Pattern 字段:

final class MappedFromYaml {
    private Pattern regexField;
    // ... accessors
}

Jackson 的 ObjectMapper 将创建一个带有默认标志的 Pattern.是否可以使用设置的特定标志来创建它，例如 Pattern.MULTILINE?理想情况下，我希望能够在 YAML 中指定这些标志，但如果未能在 Java 代码中为特定字段指定标志的解决方案也将不胜感激.

Jackson's ObjectMapper will create a Pattern with default flags. Is it possible to make it create it with specific flags set, such as Pattern.MULTILINE? Ideally I would like to be able to specify those flags in YAML, but failing that a solution that specifies the flags for a specific field in Java code would also be appreciated.

推荐答案

有两种方法.第一个是将标志直接嵌入 到正则表达式中:

There are two ways. The first is embedding flags directly into the regex:

regexField: "(\d{2}):(\d{2})(?m)"

否则不要直接映射到Pattern，而是引入一个自定义类型，比如PatternBuilder

Otherwise don't map directly to Pattern, but introduce a custom type like a PatternBuilder

public class PatternBuilder {
  public String regex;
  public boolean multiline;
  public Pattern pattern() {
    int flags = 0;
    if (multiline) flags |= Pattern.MULTILINE;
    return Pattern.compile(regex, flags);
  }
}

可以从 YAML 构建

that can be built from the YAML

pattern:
  regex: "(\d{2}):(\d{2})"
  multiline: true

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