ObjectMapper常见用法（Intro to the Jackson ObjectMapper）-Toy模板网

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maven依赖

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
    <version>2.14.2</version>
</dependency>

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Car {
    private String color;
    private String type;
}

Java Object to JSON

Json JavaObject 互相转换之序列化（jackson Java Object to JSON）

JSON to Java Object

Json JavaObject 互相转换之反序列化（jackson Json to Java Object）

JSON to Jackson JsonNode

Json JavaObject 互相转换之 jackson json to JsonNode

Creating a Java List From a JSON Array String

Json JavaObject 互相转换之 jackson Json to List

Creating Java Map From JSON String

Json JavaObject 互相转换之 jackson Json to Map

Configuring Serialization or Deserialization Feature

Json JavaObject 互相转换之序列化定制化用法
Json JavaObject 互相转换之反序列化定制化用法

Creating Custom Serializer or Deserializer

public class CustomCarSerializer extends StdSerializer<Car> {

    public CustomCarSerializer() {
        this(null);
    }

    public CustomCarSerializer(Class<Car> t) {
        super(t);
    }

    @Override
    public void serialize(Car car, JsonGenerator jsonGenerator, SerializerProvider serializer) throws IOException {
        jsonGenerator.writeStartObject();
        jsonGenerator.writeStringField("car_brand", car.getType());
        jsonGenerator.writeEndObject();
    }
}

Car car = new Car("yellow", "renault");

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule("CustomCarSerializer", new Version(1, 0, 0, null, null, null));
module.addSerializer(Car.class, new CustomCarSerializer());
mapper.registerModule(module);

String carJson = mapper.writeValueAsString(car);
System.out.println(carJson); 
// {"car_brand":"renault"}

public class CustomCarDeserializer extends StdDeserializer<Car> {

    public CustomCarDeserializer() {
        this(null);
    }

    public CustomCarDeserializer(Class<?> vc) {
        super(vc);
    }

    @Override
    public Car deserialize(JsonParser parser, DeserializationContext deserializer) throws IOException {
        Car car = new Car();
        ObjectCodec codec = parser.getCodec();
        JsonNode node = codec.readTree(parser);
        JsonNode colorNode = node.get("color");
        String color = colorNode.asText();
        car.setColor(color);
        return car;
    }
}

String json = "{ \"color\" : \"Black\", \"type\" : \"BMW\" }";

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule("CustomCarDeserializer", new Version(1, 0, 0, null, null, null));
module.addDeserializer(Car.class, new CustomCarDeserializer());
mapper.registerModule(module);

Car car = mapper.readValue(json, Car.class);
System.out.println(car); // Car(color=Black, type=null)

Handling Date Formats

Read More Jackson Date

public class Request 
{
    private Car car;
    private Date datePurchased;

    // standard getters setters
}

ObjectMapper objectMapper = new ObjectMapper();
DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm a z");
objectMapper.setDateFormat(df);
String carAsString = objectMapper.writeValueAsString(request);
// {"car":{"color":"yellow","type":"renault"},"datePurchased":"2016-07-03 11:43 AM CEST"}

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