【springboot入门之YAML使用】

YAML（YAML Ain’t Markup Language）是一种用于配置文件的格式，它支持多种数据类型，易于人类阅读和编写。以下是YAML中常见的数据类型及其使用说明：

1. 字符串

name: John Doe

Java代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "name: John Doe";Map<String, Object> data = yaml.load(yamlContent);System.out.println("Name: " + data.get("name"));}
}

输出

Name: John Doe

2. 列表（List）

fruits:- apple- banana- cherry

java 代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "fruits:\n  - apple\n  - banana\n  - cherry";Map<String, List<String>> data = yaml.load(yamlContent);List<String> fruits = data.get("fruits");System.out.println("Fruits:");for (String fruit : fruits) {System.out.println("- " + fruit);}}
}

输出

Fruits:
- apple
- banana
- cherry

3. Map

person:name: John Doeage: 28

java 代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "person:\n  name: John Doe\n  age: 28";Map<String, Map<String, Object>> data = yaml.load(yamlContent);Map<String, Object> person = data.get("person");System.out.println("Name: " + person.get("name"));System.out.println("Age: " + person.get("age"));}
}

输出

Name: John Doe
Age: 28

4. 复合结构

people:- name: John Doeage: 28- name: Jane Doeage: 25

java代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "people:\n  - name: John Doe\n    age: 28\n  - name: Jane Doe\n    age: 25";Map<String, List<Map<String, Object>>> data = yaml.load(yamlContent);List<Map<String, Object>> people = data.get("people");for (Map<String, Object> person : people) {System.out.println("Name: " + person.get("name"));System.out.println("Age: " + person.get("age"));}}
}

输出

Name: John Doe
Age: 28
Name: Jane Doe
Age: 25

5. 注释

# This is a comment
name: John Doe  # Inline comment

6. 多行字符串

block_style: |Line 1Line 2Line 3flow_style: >Line 1Line 2Line 3

java代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "block_style: |\n  Line 1\n  Line 2\n  Line 3\n" +"flow_style: >\n  Line 1\n  Line 2\n  Line 3";Map<String, Object> data = yaml.load(yamlContent);System.out.println("Block Style:\n" + data.get("block_style"));System.out.println("Flow Style:\n" + data.get("flow_style"));}
}

输出

Block Style:
Line 1
Line 2
Line 3
Flow Style:
Line 1
Line 2
Line 3

7. 布尔和Null的简写

is_active: true
middle_name: null

java代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "is_active: true\nmiddle_name: null";Map<String, Object> data = yaml.load(yamlContent);System.out.println("Is Active: " + data.get("is_active"));System.out.println("Middle Name: " + data.get("middle_name"));}
}

输出

Is Active: true
Middle Name: null

8. 锚点和别名

defaults: &defaultsadapter: postgresdatabase: railsdevelopment:database: dev_db<<: *defaults

java代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "defaults: &defaults\n  adapter: postgres\n  database: rails\n" +"development:\n  database: dev_db\n  <<: *defaults";Map<String, Object> data = yaml.load(yamlContent);Map<String, Object> defaults = (Map<String, Object>) data.get("defaults");Map<String, Object> development = (Map<String, Object>) data.get("development");System.out.println("Defaults Adapter: " + defaults.get("adapter"));System.out.println("Defaults Database: " + defaults.get("database"));System.out.println("Development Database: " + development.get("database"));System.out.println("Development Adapter: " + development.get("adapter"));}
}

输出

Defaults Adapter: postgres
Defaults Database: rails
Development Database: dev_db
Development Adapter: postgres

9. 合并多个键

defaults: &defaultsadapter: postgresdatabase: rails
person:name: John Doe<<: *defaults

java代码

public class YamlExample {public static void main(String[] args) {Yaml yaml = new Yaml();String yamlContent = "defaults: &defaults\n  adapter: postgres\n  database: rails\n" +"person:\n  name: John Doe\n  <<: *defaults";Map<String, Object> data = yaml.load(yamlContent);Map<String, Object> person = (Map<String, Object>) data.get("person");System.out.println("Name: " + person.get("name"));System.out.println("Adapter: " + person.get("adapter"));System.out.println("Database: " + person.get("database"));}
}

输出

Name: John Doe
Adapter: postgres
Database: rails