Java reads yaml data

YAML

The YAML data structure can be presented in an outline-like indentation manner. The structure is represented by indentation, and consecutive items are represented by a minus sign "-", and the key/value pairs in the map structure are separated by a colon ":".

Here are two ways for Java to read Yaml content:

1.SnakeYaml

The way to ignore comments, reading and writing will cause comments to be lost

• Add snakeyaml dependency to pom.xml:

      <!-- read and write yaml file -->
      <dependency>
		    <groupId>org.yaml</groupId>
		    <artifactId>snakeyaml</artifactId>
		    <version>1.29</version>
      </dependency>

• Specific java code:

public class YamlUtils {
    
    
    private static final Logger logger = LoggerFactory.getLogger(YamlUtils.class);

    // yml2Map: Yaml to Map, 将yaml文件读为map
    public static Map<String, Object> yml2Map(String path) throws FileNotFoundException {
    
    
        FileInputStream fileInputStream = new FileInputStream(path);
        Yaml yaml = new Yaml();
        Map<String, Object> ret = (Map<String, Object>) yaml.load(fileInputStream);
        return ret;
    }

    // map2Yml: Map to Yaml, 将map转换为yaml格式
    public static void map2Yml(Map<String, Object> map, String path) throws IOException {
    
    

        File file = new File(path);
        FileWriter fileWriter = new FileWriter(file);
        DumperOptions options = new DumperOptions();
        options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
        Yaml yaml = new Yaml(options);
        yaml.dump(map, fileWriter);
    }
 }

2.eo-yaml:

• A yaml package that supports reading and writing comments;
• When reading, generate nodes and save corresponding comments on each node;
• When writing, re-add corresponding comments according to the node;

<dependency>
    <groupId>com.amihaiemil.web</groupId>
    <artifactId>eo-yaml</artifactId>
    <version>4.3.5</version>
</dependency>

YamlMapping team = Yaml.createYamlInput(
    new File(path)
).readYamlMapping();
String architect = team.string("architect");
YamlSequence devs = team.yamlSequence("developers");
YamlSequence devops = team.yamlSequence("devops");

Map<String, Integer> grades = new HashMap<>();
grades.put("Math", 9);
grades.put("CS", 10);
YamlMapping student = Yaml.createYamlDump(
    new Student ("John", "Doe", 20, grades)
).dumpMapping();