成員參數從何而來？

Question

GroupsDTO ：

@Value
@Jacksonized
@Builder
@JsonIgnoreProperties(ignoreUnknown = true)
public class GroupsDTO {

    Response response;

    @Value
    @Jacksonized
    @Builder
    public static class Response {

        int count;

        @JsonProperty("items")
        List<GroupDTO> groups;

    }

}

GroupDTO ：

@Jacksonized
@Builder
@Value
@JsonIgnoreProperties(ignoreUnknown = true)
public class GroupDTO {

    int id;

    @JsonProperty("is_member")
    boolean isMember;

}

我有 controller：

    @ResponseStatus(HttpStatus.OK)
    @GetMapping(value = "/load"/*, produces = MediaType.APPLICATION_NDJSON_VALUE*/)
    public Mono<GroupsDTO> loadGroups() {

        var group1 = GroupDTO.builder()
                .id(1)
                .isMember(true)
                .build();

        var group2 = GroupDTO.builder()
                .id(2)
                .isMember(false)
                .build();

        var response = GroupsDTO.Response.builder()
                .count(1)
                .groups(List.of(group1, group2))
                .build();

        var groups = GroupsDTO.builder()
                .response(response)
                .build();

        return Mono.just(groups);
    }

build.gradle ：

plugins {
    id 'org.springframework.boot' version '3.0.0-SNAPSHOT'
    id 'io.spring.dependency-management' version '1.0.13.RELEASE'
    id 'java'
}
//    ...
dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-webflux'
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    implementation 'org.springframework.boot:spring-boot-starter-validation'
    compileOnly 'org.projectlombok:lombok'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    runtimeOnly 'org.postgresql:postgresql'
    annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation 'io.projectreactor:reactor-test'
}

json 執行/加載

{"response":{"count":1,"items":[{"id":1,"member":true,"is_member":true},{"id":2,"member":false,"is_member":false}]}}

成員參數從何而來？

Answer 1

在 JavaBeans 標准中，一個 boolean 屬性member將有一個名為isMember的 getter； 名為isMember的 boolean 屬性將有一個名為isIsMember的吸氣劑。 但是，Lombok 認為您可能需要isMember而不是isIsMember （合理的猜測）。

您使用 Lombok 的@Value ，它會自動創建基於成員字段正式定義屬性的 get/set 方法。 Jackson sees your boolean field isMember , which is annotated with @JsonProperty , and it renames the JSON property accordingly, but it also sees a method boolean isMember() , which it interprets as a property named member , so you get your duplicate output.

嘗試重命名您的字段boolean member以匹配 JavaBeans 約定。