Jackson简单使用

本文主要是介绍Jackson简单使用，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

Jackson简单使用

1 对象转json串

1.创建数据对象

@Data //lombok
public class User {private String name;private String sex;
}

2.代码

   public static void main(String[] args) throws JsonProcessingException {User user = new User();user.setName("名字");user.setSex("性别");ObjectMapper objectMapper = new ObjectMapper();String json = objectMapper.writeValueAsString(user);System.out.println(json); //{"name":"名字","sex":"性别"}}

2.json转对象

  public static void main(String[] args) throws IOException {String json = "{\"name\":\"名字\",\"sex\":\"性别\"}";ObjectMapper objectMapper = new ObjectMapper();User user = objectMapper.readValue(json,User.class);System.out.println(user);//User(name=名字, sex=性别)}

3.对象转Map

首先把对象转成json字符串，然后转map

    public static void main(String[] args) throws IOException {User user = new User();user.setName("名字");user.setSex("性别");ObjectMapper objectMapper = new ObjectMapper();Map<String, Object> map = objectMapper.readValue(objectMapper.writeValueAsString(user), Map.class);System.out.println(map);//{name=名字, sex=性别}}

4.对象转Map过滤值为null

我们给数据对象新增一个属性age

@Data
@ToString
public class User {private String name;private String sex;private Integer age;}

在转成Map时候结果为：
要过滤值为null只需要添加注解：@JsonInclude(JsonInclude.Include.NON_NULL)

@Data
@ToString
@JsonInclude(JsonInclude.Include.NON_NULL)
public class User {private String name;private String sex;private Integer age;}

再次转Map:

5.过滤null转空字符串

 ObjectMapper objectMapper = new ObjectMapper();objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {@Overridepublic void serialize(Object arg0, JsonGenerator arg1, SerializerProvider arg2) throws IOException, JsonProcessingException {arg1.writeString("");}});

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