不区分大小写的JSON到POJO映射，而不更改POJO

Question

有人知道com.fasterxml.jackson.DataBind.ObjectMapper是如何将JSON属性映射到POJO属性的吗？

public class Person {

    private String firstName;
    private String lastName;
    private Date dateOfBirth;

    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public Date getDateOfBirth() {
        return dateOfBirth;
    }
    public void setDateOfBirth(Date dateOfBirth) {
        this.dateOfBirth = dateOfBirth;
    }
}

@Test
public final void testDeserializingPersonJsonToPersonClass()
        throws JsonParseException, JsonMappingException, IOException {
    final String jsonAsString = "[{\"FIRSTNAME\":\"John\",\"LASTNAME\":\"Doe\",\"DATEOFBIRTH\":\"1980-07-16T18:25:00.000Z\"}]";
    final ObjectMapper mapper = new ObjectMapper();

    final Person person = mapper.readValue(jsonAsString, Person.class);

    assertNotNull(person);
    assertThat(person.getFirstName(), equalTo("John"));
}

这将导致以下错误:
com.fasterxml.jackson.DataBind.JsonMappingException：无法反序列化...

既不能更改JSON-String也不能更改pojo-class。

Answer 1

Jackson 2.5.0中引入了这种行为。可以使用MapperFeature.Accept_Case_Insensitive_Properties将映射器配置为不区分大小写。

例如：

ObjectMapper mapper = new ObjectMapper();
mapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true);