Sunday 3 June 2018

Java: YAML utility class


package com.sample.util;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.type.CollectionType;
import com.fasterxml.jackson.databind.type.MapType;
import com.fasterxml.jackson.databind.type.TypeFactory;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;

public class YAMLUtil {

 private static ObjectMapper mapper = new ObjectMapper(new YAMLFactory());

 public static void printYAML(Object obj) throws JsonGenerationException, JsonMappingException, IOException {
  mapper.writeValue(System.out, obj);
 }

 public static String getYAML(Object obj) throws JsonProcessingException {
  return mapper.writeValueAsString(obj);
 }

 public static <T> T getObject(String yaml, Class<T> clazz)
   throws JsonParseException, JsonMappingException, IOException {
  return mapper.readValue(yaml, clazz);

 }

 public static <T> List<T> getListOfObjects(String yaml, Class<T> clazz)
   throws JsonParseException, JsonMappingException, IOException {
  CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, clazz);
  List<T> listOfObjects = mapper.readValue(yaml, listType);
  return listOfObjects;
 }

 public static <K, V> Map<K, V> getMapOfObjects(String yaml, Class<K> keyClazz, Class<V> valueClazz)
   throws JsonParseException, JsonMappingException, IOException {
  TypeFactory typeFactory = mapper.getTypeFactory();
  MapType mapType = typeFactory.constructMapType(HashMap.class, keyClazz, valueClazz);
  return mapper.readValue(yaml, mapType);
 }
}

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