在 Spring Rest API 中配置 LocaldateTime

Question

我使用 Java 10 和最新的 Spring spring-boot-starter-parent 2.1.0.RELEASE

POM 配置：

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.0.RELEASE</version>
    </parent>

    <dependencies>          
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.dataformat</groupId>
            <artifactId>jackson-dataformat-xml</artifactId>
            <version>2.9.7</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.9.7</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-jaxb-annotations</artifactId>
            <version>2.9.7</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.jaxrs</groupId>
            <artifactId>jackson-jaxrs-json-provider</artifactId>
            <version>2.9.7</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.woodstox</groupId>
            <artifactId>woodstox-core-asl</artifactId>
            <version>4.4.1</version>
        </dependency>
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-core</artifactId>
            <version>2.3.0.1</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-jdk8</artifactId>
            <version>1.2.0.Final</version>
        </dependency>
        <dependency>
            <groupId>org.jxls</groupId>
            <artifactId>jxls-poi</artifactId>
            <version>1.0.15</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>8.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.security.oauth</groupId>
            <artifactId>spring-security-oauth2</artifactId>
            <version>2.3.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security.oauth.boot</groupId>
            <artifactId>spring-security-oauth2-autoconfigure</artifactId>
            <version>2.1.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.session</groupId>
            <artifactId>spring-session-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>
    </dependencies>

休息终点：

    @GetMapping("{id}")
    public ResponseEntity<?> get(@PathVariable String id) {
        return transactionRepository
                .findById(Integer.parseInt(id))
                .map(mapper::toDTO)
                .map(ResponseEntity::ok)
                .orElseGet(() -> notFound().build());
    }

DTO：

public class PaymentTransactionsDTO {

    private Integer id;

    private String status;

    private LocalDateTime created_at;

    private String merchant;
    .... getters and setters
}

但是当我尝试为 LocalDateTime created_at 返回 JSON 数据时，我得到空结果。我想 LocalDateTime 没有正确转换为 JSON 值。

你能建议我如何解决这个问题吗？

Answer 1

JSON 序列化由 Jackson 的 驱动ObjectMapper，我建议对其进行显式配置。为了正确序列化 Java 8 日期和时间对象，请确保

• 注册 JavaTimeModule
• 禁止将日期写为时间戳
• 设置日期格式（使用StdDateFormat）

说明StdDateFormat：

DateFormat标准日期序列化器和反序列化器使用的默认实现。对于序列化，默认使用 ISO-8601兼容格式（格式 String "yyyy-MM-dd'T'HH:mm:ss.SSSZ"），对于反序列化，ISO-8601 和 RFC-1123。

推荐配置：

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        return new ObjectMapper()
            .setAnnotationIntrospector(new JacksonAnnotationIntrospector())
            .registerModule(new JavaTimeModule())
            .setDateFormat(new StdDateFormat())
            .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
    }

} }

序列化日期和时间对象的示例：

• LocalDate: 2018-11-21
• LocalTime: 11:13:13.274
• LocalDateTime: 2018-11-21T11:13:13.274
• ZonedDateTime: 2018-11-21T11:13:13.274+01:00

编辑：独立依赖项（已经包含在 中spring-boot-starter-web）：

• com.fasterxml.jackson.core:jackson-annotations
• com.fasterxml.jackson.core:jackson-databind
• com.fasterxml.jackson.datatype:jackson-datatype-jsr310

Answer 2

尝试在您的created_at字段上使用@JsonFormat。

@JsonFormat(pattern="yyyy-MM-dd")
@DateTimeFormat(iso = DateTimeFormat.ISO.TIME)
private LocalDateTime created_at;