# Jackson基本用法

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.10.2</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.2</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.10.2</version>
</dependency>

public static void main(String[] args){
        ObjectMapper objectMapper = new ObjectMapper();
        //序列化
        Person p = new Person();
        p.setName("jiay");
        p.setAge(50);
        p.setPosition("山东济南");
        try {
            String pJson = objectMapper.writeValueAsString(p);
            System.out.println("序列化结果:" + pJson);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        //反序列化
        String personJson = "{\"name\":\"jiay\",\"age\":\"50\",\"position\":\"xxx\"}";
        try {
            Person person = objectMapper.readValue(personJson,Person.class);
            System.out.println("反序列化结果:" + person.getName() + ":" + person.getAge());
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        //字符串转JsonNode
        try {
            JsonNode jsonNode = objectMapper.readTree(personJson);
            System.out.println("string2JsonNode结果: name:" + jsonNode.get("name").textValue());
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        //object转JsonNode
        JsonNode jsonNode2 = objectMapper.valueToTree(p);
        System.out.println("object2JsonNode结果：name:" + jsonNode2.get("name").textValue());
        //JsonNode转object
        try {
            Person person = objectMapper.treeToValue(jsonNode2,Person.class);
            System.out.println("JsonNode2object结果：name:" + person.getName());
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        //map转JsonNode
        Map<String,String> map = new HashMap<>();
        map.put("name","jiay");
        map.put("age","50");
        JsonNode mapNode = objectMapper.valueToTree(map);
        System.out.println("map2JsonNode结果：name:" + mapNode.get("name").textValue());
        //ArrayList转ArrayNode
        List<String> friendList = new ArrayList<>();
        friendList.add("jack");
        friendList.add("lucy");
        ArrayNode arrayNode = objectMapper.valueToTree(friendList);
        //ObjectNode
        ObjectNode rootNode = objectMapper.createObjectNode();
        rootNode.put("name",p.getName());
        rootNode.set("friends",arrayNode);
        ArrayList<ObjectNode> hobby = new ArrayList<ObjectNode>();
        ObjectNode bs = objectMapper.createObjectNode();
        bs.put("name","basketball");
        hobby.add(bs);
        ObjectNode bs2 = objectMapper.createObjectNode();
        bs2.put("name","program");
        hobby.add(bs2);
        rootNode.putArray("hobby").addAll(hobby);
        try {
            System.out.println("root:" + objectMapper.writeValueAsString(rootNode));
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
    }
    @Getter
    @Setter
    static class Person{
        private String name;
        private int age;
        private String position;

        public Person(){}
    }