Question

我有一个包含Java 8日期时间类型字段的实体。问题是这些字段被序列化为对象。我添加了jackson-datatype-jsr310依赖项，因此Spring Boot 1.5.7会自动配置处理Java 8日期时间类型的JavaTimeModule。似乎模块没有注册（我在JavaTimeModule构造函数中放了一个断点）。我知道我不需要自定义ObjectMapper。我花了几个小时阅读这个问题，解决方案总是添加jackson-datatype-jsr310依赖项，但在我的情况下它不起作用。

实体：

@Entity
public class DateTimeEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private LocalDate localDate;

    private LocalDateTime localDateTime;

    private Instant instant;

    private OffsetDateTime offsetDateTime;

    private ZonedDateTime zonedDateTime;

}

RestController方法：

@GetMapping("/datetimes/{id}")
public ResponseEntity<DateTimeEntity> getById(@PathVariable Long id) {
    DateTimeEntity dateTimeEntity = dateTimeRepository.findOne(id);
    return new ResponseEntity<DateTimeEntity>(dateTimeEntity, HttpStatus.OK);

}

返回JSON对象：

    {
    "id": 1,
    "localDate": null,
    "localDateTime": null,
    "instant": {
        "epochSecond": 1508772600,
        "nano": 0
    },
    "offsetDateTime": {
        "offset": {
            "totalSeconds": 0,
            "id": "Z",
            "rules": {
                "fixedOffset": true,
                "transitionRules": [],
                "transitions": []
            }
        },
        "dayOfMonth": 23,
        "dayOfWeek": "MONDAY",
        "dayOfYear": 296,
        "month": "OCTOBER",
        "monthValue": 10,
        "year": 2017,
        "hour": 15,
        "minute": 30,
        "nano": 0,
        "second": 0
    },
    "zonedDateTime": {
        "offset": {
            "totalSeconds": 0,
            "id": "Z",
            "rules": {
                "fixedOffset": true,
                "transitionRules": [],
                "transitions": []
            }
        },
        "zone": {
            "totalSeconds": 0,
            "id": "Z",
            "rules": {
                "fixedOffset": true,
                "transitionRules": [],
                "transitions": []
            }
        },
        "dayOfMonth": 23,
        "dayOfWeek": "MONDAY",
        "dayOfYear": 296,
        "month": "OCTOBER",
        "monthValue": 10,
        "year": 2017,
        "hour": 15,
        "minute": 30,
        "nano": 0,
        "second": 0,
        "chronology": {
            "id": "ISO",
            "calendarType": "iso8601"
        }
    }
}

POM文件：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>framework-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
        <mockito.version>2.11.0</mockito.version>
        <org.mapstruct.version>1.2.0.Final</org.mapstruct.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-jdk8</artifactId>
            <version>${org.mapstruct.version}</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-jsr310</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-jsr310</artifactId>
            <version>${jackson.version}</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>${org.mapstruct.version}</version>
                        </path>
                    </annotationProcessorPaths>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.asciidoctor</groupId>
                <artifactId>asciidoctor-maven-plugin</artifactId>
                <version>1.5.5</version>
                <executions>
                    <execution>
                        <id>output-html</id>
                        <phase>generate-resources</phase>
                        <goals>
                            <goal>process-asciidoc</goal>
                        </goals>
                        <configuration>
                            <backend>html</backend>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Answer 1

根据How to customize ObjectMapper：

任何类型为com.fasterxml.jackson.databind.Module的bean都将是自动注册自动配置 Jackson2ObjectMapperBuilder并应用于任何ObjectMapper实例它创造了。这提供了一种全球性的贡献机制向应用程序添加新功能时的自定义模块。

仅添加依赖是不够的，您必须声明一个@Bean模块，如下所示：

@Bean
public Module dateTimeModule(){
    return new new JavaTimeModule();
}

不推荐使用

Plus jackson-datatype-jsr310模块，而应使用JavaTimeModule。

Answer 2

解决方案是将依赖项添加到类路径中。出于某种原因，它不在IDE中。

即使不推荐使用依赖项，它仍然由spring-boot-autoconfigure模块使用。见Spring Boot Code

   <dependency>
        <groupId>com.fasterxml.jackson.datatype</groupId>
        <artifactId>jackson-datatype-jsr310</artifactId>
    </dependency>

当它在类路径中时，Java 8日期和时间对象被序列化为时间戳。

Answer 3

我在将 spring boot 从 2.3.7 升级到 2.5.1 时开始遇到这个问题。

如果您定义了 ObjectMapper @Bean，那么您需要使用它注册时间模块。

@Bean
public ObjectMapper defaultMapper() {
    ObjectMapper objectMapper = new ObjectMapper(); 
    objectMapper.registerModule(new JavaTimeModule()); 
    return objectMapper;
}

很多时候，编码人员在使用 jackson 序列化时只会创建一个“new ObjectMapper()”，因此请注意使用 vanilla mapper，而不是自动装配已注册时间模块的预配置默认值。

如前所述，您将需要 jackson-datatype-jsr310，但这已作为托管版本包含在 Spring Boot 中。

如果你没有手动定义对象映射器 bean，那么 Spring Boot 应该会自动提供一个注册了时间模块的对象。

使用Spring Boot将Java 8日期时间类型序列化为对象

3 个答案: