使用Jersey和Jackson序列化（延迟加载）实体

Question

我正在为我的REST API使用Jersey-Spring4。 这是我相关的pom.xml部分：

<properties>
        <jersey.version>2.25.1</jersey.version>
        <guava.version>19.0</guava.version>
        <jackson.version>2.25.1</jackson.version>
        <slf4j.version>1.7.12</slf4j.version>
        <logback.version>1.1.3</logback.version>
        <antisamy.version>1.5.3</antisamy.version>
        <spring.version>4.3.7.RELEASE</spring.version>
        <junit.version>4.12</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.openkm</groupId>
            <artifactId>sdk4j</artifactId>
            <version>2.3</version>
        </dependency>

        <!-- Servlet -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <!-- JAX-RS -->
        <dependency>
            <groupId>javax.ws.rs</groupId>
            <artifactId>javax.ws.rs-api</artifactId>
            <version>2.0.1</version>
            <scope>compile</scope>
        </dependency>

        <!-- Jersey -->
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.core</groupId>
            <artifactId>jersey-server</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-jackson</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-multipart</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.ext</groupId>
            <artifactId>jersey-bean-validation</artifactId>
            <version>${jersey.version}</version>
        </dependency>

        <!--
Note: There is a bug of jersey-spring3 -> https://java.net/jira/browse/JERSEY-2038
-->
        <dependency>
            <groupId>org.glassfish.jersey.ext</groupId>
            <artifactId>jersey-spring3</artifactId>
            <version>${jersey.version}</version>
            <exclusions>
                <exclusion>
                    <artifactId>spring-context</artifactId>
                    <groupId>org.springframework</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>spring-beans</artifactId>
                    <groupId>org.springframework</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>spring-core</artifactId>
                    <groupId>org.springframework</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>spring-web</artifactId>
                    <groupId>org.springframework</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>jersey-server</artifactId>
                    <groupId>org.glassfish.jersey.core</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>
                        jersey-container-servlet-core
                    </artifactId>
                    <groupId>org.glassfish.jersey.containers</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>hk2</artifactId>
                    <groupId>org.glassfish.hk2</groupId>
                </exclusion>
            </exclusions>
        </dependency>

        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.11.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>4.3.5.RELEASE</version>
        </dependency>

        <!-- Google Guava -->
        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>${guava.version}</version>
        </dependency>
        <!-- logging -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>${logback.version}</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>${logback.version}</version>
        </dependency>
        <dependency>
            <groupId>org.owasp.antisamy</groupId>
            <artifactId>antisamy</artifactId>
            <version>${antisamy.version}</version>
        </dependency>

        <!-- Apache HTTP Client -->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>fluent-hc</artifactId>
            <version>4.5.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpmime</artifactId>
            <version>4.5.2</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.9.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.1-api</artifactId>
            <version>1.0.0.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-envers</artifactId>
            <version>5.2.9.Final</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-hibernate5</artifactId>
            <version>2.8.4</version>
        </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.0.0</version>
        </dependency>

        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <version>1</version>
        </dependency>

        <!-- Test -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.hamcrest</groupId>
            <artifactId>hamcrest-library</artifactId>
            <version>1.3</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>

        <!-- Swagger dependencies -->
        <dependency>
            <groupId>io.swagger</groupId>
            <artifactId>swagger-jersey2-jaxrs</artifactId>
            <scope>compile</scope>
            <version>1.5.13</version>
        </dependency>

        <dependency>
            <groupId>com.nimbusds</groupId>
            <artifactId>nimbus-jose-jwt</artifactId>
            <version>4.0</version>
        </dependency>

        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>2.9.9</version>
        </dependency>

    </dependencies>

现在，这就是我配置项目的方式：

    @Configuration("appConfig")
@ComponentScan(value = "com.nws.vedica", lazyInit = true)
@PropertySource({"classpath:swagger.properties", "classpath:vedica.properties"})
@ApplicationPath("/api")
@EnableJpaAuditing(auditorAwareRef="auditorProvider")
public class VedicaConfig extends ResourceConfig {

public VedicaConfig() {
    packages("com.nws.vedica");
    property(ServletProperties.FILTER_FORWARD_ON_404, true);
    register(MultiPartFeature.class);
    register(JacksonFeature.class);
//        register(MOXyJsonProvider.class);
        register(ValidationFeature.class);
        register(ValidationConfigurationContextResolver.class);
        register(PropertySourcesPlaceholderConfigurer.class);

    register(ApiListingResource.class);
    register(SwaggerSerializers.class);
}

@Bean
AuditorAware<String> auditorProvider() {
    return new AuditorAware<String>() {
        @Override
        public String getCurrentAuditor() {
            return "qwer";
        }
    };
}

@Bean
public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
    return new PersistenceExceptionTranslationPostProcessor();
}
}

现在，我最大的烦人的问题是，当我返回其中包含延迟获取实体的实体时，会出现WARNING: com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: com.nws.vedica.model.entity.PartyKind["doc2"]->com.nws.vedica.model.entity.Document2["docType"]->com.nws.vedica.model.entity.DocType["validityRule"]->com.nws.vedica.model.entity.ValidityRule["validFrom"])异常。

Okey，我浏览了许多文章和主题，告诉我必须使用

<dependency>
        <groupId>com.fasterxml.jackson.datatype</groupId>
        <artifactId>jackson-datatype-hibernate5</artifactId>
        <version>2.8.4</version>
    </dependency>

包来让杰克逊初始化我的实体（都是FetchType.EAGER，所以我真的不知道为什么会这样）。

因此，当我添加jackson-datatype-hibernate5依赖项并将其注册在config中时，如下所示：

@Bean
public Module datatypeHibernateModule() {
    return new Hibernate5Module();
}

但是我仍然遇到同样的例外。 我的观点是，我需要为球衣选择不同的datatype-hibernate5 hibernate程序包，但找不到哪个。 或以其他方式注册。

你能建议如何使这项工作吗？ 谢谢

Answer 1

看起来您没有使用Spring Boot。 作为Spring bean的Module仅适用于Spring Boot。 如果要使用Jersey配置杰克逊，则应使用ContextResolver ，在其中可以配置ObjectMapper 。

@Provider
public class ObjectMapperContextResolver implements ContextResolver<ObjectMapper> {

    private final ObjectMapper mapper;

    public ObjectMapperContextResolver() {
        mapper = new ObjectMapper();
        mapper.registerModule(new Hibernate5Module());
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return mapper;
    }
}

然后在泽西岛注册

register(ObjectMapperContextResolver.class);