使用Spring在Jersey 2中定制Jackson ObjectMapper

Question

我在将泽西岛从1.x迁移到2.x时遇到了一些问题。我的应用程序使用Jersey提供REST Web服务，通​​过Jackson和Spring 4以JSON方式提供数据来处理依赖注入。

在Jersey 1.xi曾经将JsonDeserializer编写为由Spring管理的组件，所以我可以在反序列化期间访问我的服务以从persistance层加载我的域对象，但在2.x中我遇到了注入问题解串器中的服务工作。我所采用的方法受到了这篇博文的启发：http://www.runningasroot.com/blog/2012/05/02/autowiring-jackson-deserializers-in-spring/

这是我的 pom.xml 的依赖部分：

<dependencies>
    <!-- Spring -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <!-- Jersey -->
    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-servlet</artifactId>
        <version>${jersey.version}</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.ext</groupId>
        <artifactId>jersey-spring3</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.media</groupId>
        <artifactId>jersey-media-json-jackson</artifactId>
        <version>${jersey.version}</version>
    </dependency>
    <!-- Commons Codec -->
    <dependency>
        <groupId>commons-codec</groupId>
        <artifactId>commons-codec</artifactId>
        <version>${commons-codec.version}</version>
    </dependency>

    <!-- cut -->

<dependencies>

泽西岛版本是2.7，Spring 4.0.2.RELEASE。

这是我的 web.xml ：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

    <module-name>myApp/module-name>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </param-value>
    </context-param>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>it.mgt.myApp.config.ApplicationConfig</param-value>
    </context-param>

    <servlet>
        <servlet-name>jersey-serlvet</servlet-name>
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
        <init-param>
            <param-name>javax.ws.rs.Application</param-name>
            <param-value>it.mgt.myApp.config.JerseyConfig</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>jersey-serlvet</servlet-name>
        <url-pattern>/api/*</url-pattern>
    </servlet-mapping>

</web-app>

这是我的 Spring配置类：

@Configuration
@ComponentScan({"it.mgt.myApp"})
@PropertySource("classpath:myApp.properties")
public class ApplicationConfig {

    // Cut

}

这是我的泽西资源配置类：

public class JerseyConfig extends ResourceConfig {

    public JerseyConfig() {
        packages("it.mgt.myApp");

        register(MultiPartFeature.class);

        register(RequestContextFilter.class);

        register(ObjectMapperContextResolver.class);
        register(JacksonFeature.class);

        register(CorsRequestFilter.class);
        register(SignatureProcessingFilter.class);
        register(AuthorizationFeature.class);
        register(CorsResponseFilter.class);
        register(new UserBinder());
    }
}

这是我的 ObjectMapperContextResolver 类：

@Component
@Provider
public class ObjectMapperContextResolver implements ContextResolver<ObjectMapper> {

    @Autowired
    private SpringObjectMapper objectMapper;

    public ObjectMapperContextResolver() {
        super();
    }

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

}

我认为@Provider注释与资源配置类中的registrationg是多余的。

这是我的 SpringObjectMapper 类：

@Component
public class SpringObjectMapper extends ObjectMapper {

    private static final long serialVersionUID = 1413033425692174337L;

    @Autowired
    ApplicationContext applicationContext;

    public SpringObjectMapper() {
        this.setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL);
        this.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, true);
    }

    @Override
    @Autowired
    public void setHandlerInstantiator(HandlerInstantiator hi) {
        super.setHandlerInstantiator(hi);
    }

}

这是我的 SpringBeanHandlerInstantiator 类：

@Component
public class SpringBeanHandlerInstantiator extends HandlerInstantiator {

    private ApplicationContext applicationContext;

    @Autowired
    public SpringBeanHandlerInstantiator(ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }

    @Override
    public JsonDeserializer<?> deserializerInstance(DeserializationConfig dc, Annotated antd, Class<? extends JsonDeserializer<?>> type) {
        try {
            return (JsonDeserializer<?>) applicationContext.getBean(type);
        } catch (Exception e) {
        }

        return null;
    }

    @Override
    public KeyDeserializer keyDeserializerInstance(DeserializationConfig dc, Annotated antd, Class<? extends KeyDeserializer> type) {
        try {
            return (KeyDeserializer) applicationContext.getBean(type);
        } catch (Exception e) {
        }

        return null;
    }

    @Override
    public JsonSerializer<?> serializerInstance(SerializationConfig sc, Annotated antd, Class<? extends JsonSerializer<?>> type) {
        try {
            return (JsonSerializer<?>) applicationContext.getBean(type);
        } catch (Exception e) {
        }

        return null;
    }

    @Override
    public TypeResolverBuilder<?> typeResolverBuilderInstance(MapperConfig<?> mc, Annotated antd, Class<? extends TypeResolverBuilder<?>> type) {
        try {
            return (TypeResolverBuilder<?>) applicationContext.getBean(type);
        } catch (Exception e) {
        }

        return null;
    }

    @Override
    public TypeIdResolver typeIdResolverInstance(MapperConfig<?> mc, Annotated antd, Class<? extends TypeIdResolver> type) {
        try {
            return (TypeIdResolver) applicationContext.getBean(type);
        } catch (Exception e) {
        }

        return null;
    }

}

这是我的域实体类，序列化器和反序列化器是静态内部类：

@JsonSerialize(using = User.Serializer.class)
@JsonDeserialize(using = User.Deserializer.class)
public class User {

    @Component
    public static class Serializer extends JsonSerializer<User> {

        @Override
        public void serialize(User obj, JsonGenerator jg, SerializerProvider sp) throws IOException, JsonProcessingException {
            // Cut
        }

    }

    @Component
    public static class Deserializer extends JsonDeserializer<User> {

        @Autowired
        SomeService someService;

        @Override
        public User deserialize(JsonParser jp, DeserializationContext dc) throws IOException, JsonProcessingException {
            User user = new User();

            // Cut
            // Use someService here
        }

    }

    // Cut

}

我试图在ObjectMapperContextResolver.getContext（Class类型）中放置一个brakpoint，但它永远不会被击中，我怀疑这是问题的根源，但经过两天的尝试和研究球衣文档后，我的想法已经用完了。

任何人都可以指出我如何正确地解决这个问题？

Answer 1

经过进一步尝试后，发现ObjectMapperContextResolver上的@Component导致Jersey 2.x不使用提供程序，即使它在Jersey配置类中显式注册。这与Jersey 1.x行为相反，需要@Component。

删除它就行了，但看起来很奇怪。 ObjectMapperContextResolver中的@Autowired SpringObjectMapper仍由Jersey注入。

从球衣文件中我无法判断这是设计还是错误。