Jackson 中的 JSON 中的 Configure() 方法

Jackson 是當(dāng)前用的比較廣泛的，用來(lái)序列化和反序列化 json 的 Java 的開(kāi)源框架。下面文章將和大家講講 Jackson中的json中的Configure()方法的詳細(xì)內(nèi)容。

1. #configure(JsonParser.Feature, boolean):

public class StrictDuplicateMapper {
    public static void main(String[] args) throws JsonProcessingException {
        String json = "{" +
                  "\"name\":\"Ali Z\", " +
                  "\"name\":\"Ali Zh\"" + // will throw exception because that field is duplicated
                "}";

        ObjectMapper mapper = new ObjectMapper()
                .configure(JsonParser.Feature.STRICT_DUPLICATE_DETECTION, true)
                .enable(JsonParser.Feature.STRICT_DUPLICATE_DETECTION);// another way of enabling featur
        mapper.readValue(json, Person.class);
    }

    public static class Person {
        private String name;

        @JsonCreator
        public Person(@JsonProperty("name") String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}

2. ObjectMapper#configure(JsonGenerator.Feature, boolean)：

public class JsonGeneratorExample {

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper()
                .configure(JsonGenerator.Feature.WRITE_BIGDECIMAL_AS_PLAIN, true);

        Person person = new Person();
        person.setAge(BigDecimal.valueOf(12334535345456700.12345634534534578901));

        String json = mapper.writeValueAsString(person);

        System.out.println(json);
    }

    public static class Person {
        private BigDecimal age;

        public BigDecimal getAge() {
            return age;
        }

        public void setAge(BigDecimal age) {
            this.age = age;
        }
    }
}

3. ObjectMapper#configure(SerializationFeature, boolean)：

{"name":"Ali Z"}

{"Person":{"name":"Ali Z"}}

{"name":"Ali Z"}

{"name":"Ali Z"}

2011-12-03T10:15:30+01:00[歐洲/巴黎]

{"surname":["Z","h","a","g","p","a","r","o","v"]}

{"surname":"Zhagparov"}

{"permissionEnum":"管理員"}

{"permissionEnum":0}

{"permissionEnum":{"0":"admin"}}

{"permissionEnum":{"ADMIN":"admin"}}

{"stringList":"Ali Z"}

{"stringList":["Ali Z"]}

{“date”：[2021,6,20,14,16,48,260]}

{“date”：[2021,6,20,14,17,12,990000000]}

public class JsonSerializationFeatureExample {

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper()
                .configure(SerializationFeature.WRAP_ROOT_VALUE, true)
                .configure(SerializationFeature.INDENT_OUTPUT, true);

        Person person = new Person();
        person.setName("Ali Z");

        String json = mapper.writeValueAsString(person);

        System.out.println(json);
    }

    public static class Person {
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}

4. ObjectMapper#configure(DeserializationFeature, boolean)：

{"Person":{"name":"Ali Z"}}

{"name":"Ali Z"}

public static class Person{
    private int age；
}

{“age”：””}

public static class Person{    private int age；
}

{“age”：[]}

public class DeserializeExample {
    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper()
                .configure(DeserializationFeature.FAIL_ON_MISSING_CREATOR_PROPERTIES, true)
                .enable(DeserializationFeature.FAIL_ON_MISSING_CREATOR_PROPERTIES);

        Person person = mapper.readValue("{}", Person.class);
    }


    public static class Person {
        private Integer age;

        @JsonCreator
        public Person(@JsonProperty("age") Integer age) {
            this.age = age;
        }

        public Integer getAge() {
            return age;
        }

        public void setAge(Integer age) {
            this.age = age;
        }

        @Override
        public String toString() {
            return "Person{" +
                    "age=" + age +
                    '}';
        }
    }
}