java - 在 Jboss EAP 7.2.0.GA 中处理 JSON 序列化

Question

在我的 Jboss 中，我尝试使用 JAX-RS 实现 REST 服务。它应该返回某个对象的 JSON 序列化版本

 @GET
  @Produces({ MediaType.APPLICATION_JSON })
  public BlacklistDTO getByName(
      @QueryParam("gav") final List<String> gavStringList)
  {
     ...
  }

对象的某些部分没有正确序列化(结果为空)。我如何处理/自定义 Jboss 生成 JSON 的方式？

Answer 1

您可以自定义实用程序的配置以序列化/反序列化 JSON(通常是 EAP 中包含的 Jackson)，并配置/注册模块到 Jackson，指示如何对复杂对象执行此工作。

如果您使用的是 CDI + Resteasy + Jackson，您可以:

1. 提供一个 JAX-RS 自定义 Json 提供程序，您可以在其中使用自定义配置配置 Jackson ObjectMapper。例如。

   @Provider
   @Produces(MediaType.APPLICATION_JSON)
   public class CustomJsonProvider implements ContextResolver<ObjectMapper> {
   private final ObjectMapper mapper;
   
   public CustomJsonProvider() {
       ObjectMapper mapperCdi = null;
       //if you are using CDI and you have your own Custom Object Mapper...
       BeanManager bm = CDI.current().getBeanManager();
       Set<Bean<?>> sBeans = bm.getBeans(ObjectMapper.class);
       if (sBeans != null && !sBeans.isEmpty()) {
           @SuppressWarnings("unchecked")
           Bean<ObjectMapper> bean = (Bean<ObjectMapper>) sBeans.iterator().next();
           CreationalContext<ObjectMapper> ctx = bm.createCreationalContext(bean);
           mapperCdi = (ObjectMapper) bm.getReference(bean, ObjectMapper.class, ctx);
       }
       if (mapperCdi != null) {
           mapper = mapperCdi;
       }else {
       //if you are not using CDI, you can create your own Custom Object Mapper or get it from a factory e.g you can do here AppConfig.getObjectMapperInstance() or create a new one
           mapper = new ObjectMapper();
           //eg. configuration of Hibernate 5 - Jackson Module
           Hibernate5Module h5m = new Hibernate5Module();
           h5m.configure(Hibernate5Module.Feature.SERIALIZE_IDENTIFIER_FOR_LAZY_NOT_LOADED_OBJECTS, true);
           mapper.registerModule((com.fasterxml.jackson.databind.Module) h5m);
   
           mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
                   .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, true);
           mapper.setSerializationInclusion(Include.NON_NULL);
   
           //eg. custom Jackson SimpleModule registration
           SimpleModule module = new SimpleModule("PaginationModule") {
               private static final long serialVersionUID = 1L;
   
               @Override
               public void setupModule(SetupContext context) {
                   context.addAbstractTypeResolver(
                           new SimpleAbstractTypeResolver().addMapping(Slice.class, SliceClientImpl.class));
                   context.addAbstractTypeResolver(
                           new SimpleAbstractTypeResolver().addMapping(Page.class, PageClientImpl.class));
               }
           };
           mapper.registerModule(module);
       }
   }
   
   @Override
   public ObjectMapper getContext(Class<?> objectType) {
       return mapper;
   }
   }
   

2. 如果您使用 CDI，请定义您的“生产者”方法 (@Produce) 和您的 Jackson ObjectMapper 工厂:

   @ApplicationScoped
   public class AppConfig {
   private static ObjectMapper objectMapper;
   // Jackson Object Mapper
   @Produces
   public ObjectMapper createMapper() {
       return AppConfig.getObjectMapperInstance();
   }
   
   public static ObjectMapper getObjectMapperInstance() {
       if (objectMapper == null) {
           objectMapper = new ObjectMapper();
   
           //eg. configuration of Hibernate 5 - Jackson Module
           //Hibernate5Module h5m = new Hibernate5Module();
           //h5m.configure(Hibernate5Module.Feature.SERIALIZE_IDENTIFIER_FOR_LAZY_NOT_LOADED_OBJECTS, true);
           //objectMapper.registerModule((com.fasterxml.jackson.databind.Module) h5m);
   
           //eg. configuration of Joda - Jackson Module
           objectMapper.registerModule(new JodaModule());
           objectMapper.setTimeZone(TimeZone.getDefault());
           objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
                   .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
           objectMapper.setSerializationInclusion(Include.NON_NULL);
   
           //eg. custom Jackson SimpleModule registration
           SimpleModule module = new SimpleModule("PaginationModule") {
               private static final long serialVersionUID = 1L;
               @Override
               public void setupModule(SetupContext context) {
                   context.addAbstractTypeResolver(
                           new SimpleAbstractTypeResolver().addMapping(Slice.class, SliceClientImpl.class));
                   context.addAbstractTypeResolver(
                           new SimpleAbstractTypeResolver().addMapping(Page.class, PageClientImpl.class));
               }
           };
           objectMapper.registerModule(module);
   
       }
       return objectMapper;
   }
   }
   

3. 检查您的提供商是否已通过 Jax-rs/Resteasy 注册:

如果您的 jackson 配置未注册，请尝试将以下行添加到您的 web.xml 中的上下文中:

<context-param>

  <param-name>resteasy.providers</param-name>

  <param-value>your.package.CustomJsonProvider</param-value>

</context-param>

有时，需要配置为服务提供者，添加一个文件“META-INF/services/javax.ws.rs.ext.Providers”(或者在 WEB-INF 中，具体取决于您使用 war 的包装类型， ear, jar, etc.) 内容如下:

your.package.CustomJsonProvider

---

以另一种方式，您可以返回一个String(或一个Response 对象)，在您的服务中注入(inject)您的ObjectMapper(或您处理JSON 格式的实用程序)并创建/在返回语句之前序列化您的对象。

例如。使用 Json-b

@Path("/myservice")
public class MyService {

    @POST
    @Produces(MediaType.APPLICATION_JSON)
    @Path("/resources")
    public Response createJson(@FormParam("name") String name, @FormParam("surname") String surname) {
        Response response;
        User u = new User(name, surname);
        Jsonb jsonb = JsonbBuilder.create();
        String jsonString = jsonb.toJson(u);
        response = Response.ok(jsonString).build();

        return response;
    }
}

例如。使用 json-b 以编程方式创建自定义 json

 // Create Json and serialize    
 JsonObject json = Json.createObjectBuilder()
 .add("name", "Falco")
 .add("age", BigDecimal.valueOf(3))
 .add("biteable", Boolean.FALSE).build();    String result = json.toString();

例如。使用 Jackson 以编程方式创建自定义 json

    ObjectMapper mapper = new ObjectMapper();
    ArrayNode arrayNode = mapper.createArrayNode();
    ObjectNode objectNode1 = mapper.createObjectNode();
    objectNode1.put("name", "Anna");
    objectNode1.put("surname", "T");
    arrayNode.add(objectNode1);
    ObjectNode objectNode2 = mapper.createObjectNode();
    objectNode2.put("name", "John");
    objectNode2.put("surname", "X");
    arrayNode.add(objectNode2);

    String json = arrayNode.toString();

希望对您有所帮助。