Java中注解@JsonFormat的用法详解

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum EmployeeType {
    FullTime("Full Time"), PartTime("Part Time");

    private String displayName;

    EmployeeType(String displayName) {
        this.displayName = displayName;
    }

    public String getDisplayName() {
        return displayName;
    }
}

public class Employee {
    private String name;
    private EmployeeType employeeType;
    ...
}    

public class ExampleMain {
    public static void main(String[] args) throws IOException {
        Employee employee = new Employee();
        employee.setName("Amy");
        employee.setEmployeeType(EmployeeType.PartTime);

        System.out.println("-- before serialization --");
        System.out.println(employee);

        System.out.println("-- after serialization --");
        ObjectMapper om = new ObjectMapper();
        String jsonString = om.writeValueAsString(employee);
        System.out.println(jsonString);

        System.out.println("-- after deserialization --");
        System.out.println(om.readValue(jsonString, Employee.class));
    }
}

-- before serialization --
Employee{name='Amy', employeeType=PartTime}
-- after serialization --
{"name":"Amy","employeeType":{"displayName":"Part Time"}}
-- after deserialization --
Exception in thread "main" com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `org.example.c27.EmployeeType` from Object value (token `JsonToken.START_OBJECT`)
 at [Source: (String)"{"name":"Amy","employeeType":{"displayName":"Part Time"}}"; line: 1, column: 30] (through reference chain: org.example.c27.Employee["employeeType"])
	at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
	at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1601)
	at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1375)
	at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1280)
	at com.fasterxml.jackson.databind.DeserializationContext.extractScalarFromObject(DeserializationContext.java:872)
	at com.fasterxml.jackson.databind.deser.std.EnumDeserializer.deserialize(EnumDeserializer.java:199)
	at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:324)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:187)
	at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:322)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4593)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3548)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3516)
	at org.example.c27.ExampleMain.main(ExampleMain.java:28)

Process finished with exit code 1

-- before serialization --
Employee{name='Amy', employeeType=PartTime}
-- after serialization --
{"name":"Amy","employeeType":"PartTime"}
-- after deserialization --
Employee{name='Amy', employeeType=PartTime}