Glassfish获得JSON服务500错误- MessageBodyWriter未找到

Question

我得到了

找不到媒体类型为MessageBodyWriter =application/json、type=class java.util.HashMap$Values、genericType=java.util.Collection

来自一个带有Glassfish 4.1的web服务。我看到的每一件事都说要在类路径中有jackson或其他库，这样就可以转换类型。用玻璃鱼，我有：

~/apps/glassfish-4.1/glassfish/domains/domain1/logs$ find ../../../../ | grep jackson
../../../../glassfish/modules/jackson-core.jar
../../../../glassfish/modules/jackson-annotations.jar
../../../../glassfish/modules/jackson-databind.jar
../../../../glassfish/modules/jackson-jaxrs-json-provider.jar
../../../../glassfish/modules/jackson-jaxrs-base.jar
../../../../glassfish/modules/jersey-media-json-jackson.jar

实体类：

public class Actor extends AbstractBaseEntity{
    public Actor(String id, String name) {
        super(id, name);
    }
}

public class AbstractBaseEntity {
    String identifier;
    String name;

    public AbstractBaseEntity(String id, String name){
        this.identifier = id;
        this.name = name;
    }

    public String getIdentifier() {
        return identifier;
    }

    public String getName() {
        return name;
    }
}

服务舱：

@Path("actors")
public class MockActorService {
    private static final int DEFAULT_COUNT = 5;
    HashMap<String, Actor> items;
    public MockActorService() throws WFlowServiceException {
        this(MockActorService.DEFAULT_COUNT);
    }

    public MockActorService(int actors) throws WFlowServiceException {
        items = new HashMap<>();
        for (int i = 0; i < actors; i++) {
            Actor a = new Actor("ID:" + i, "Actor Name " + i);
            items.put(a.getIdentifier(), a);
        }
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response getAll() throws WFlowServiceException {
        GenericEntity< Collection< Actor > > entity;
        Collection<Actor> vals = items.values();
        entity = new GenericEntity<Collection<Actor>>(vals){};
        return Response.ok(entity).build();
    }
}

为什么我还会犯这个错误？

Answer 1

是的，Glassfish有Jackson，但它也有MOXy，这是默认的提供者。有些类型的MOXy很奇怪。如果要禁用MOXy以便可以使用杰克逊，则需要将以下属性设置为true

ServerProperties.MOXY_JSON_FEATURE_DISABLE

我已经有一段时间没有使用玻璃鱼了，所以我不确定你是否还需要注册杰克逊，但我很确定你没有，它应该自动注册。MOXy基本上阻止它注册。

Answer 2

好的，经过一番挖掘，我想出了以下的方法来解决这个问题。@peeskillet在一定程度上是正确的，这种修正是针对玻璃鱼的。

以下是包含更多上下文的博客

这是修复它的方法。我需要实现以下两个类：

public class JacksonFeature implements Feature {

    Logger L = LoggerFactory.getLogger(JacksonFeature.class);

    @Override
    public boolean configure(final FeatureContext context) {
        String postfix = "";

        postfix = '.' + context.getConfiguration().getRuntimeType().name().toLowerCase();
        context.property(CommonProperties.MOXY_JSON_FEATURE_DISABLE + postfix, true); 

        L.info("Set property to true disable MOXY: " + CommonProperties.MOXY_JSON_FEATURE_DISABLE + postfix);
        context.register(JsonParseExceptionMapper.class);
        context.register(JsonMappingExceptionMapper.class);
        context.register(JacksonJsonProvider.class, MessageBodyReader.class, MessageBodyWriter.class);
        return true;
    }
}

@javax.ws.rs.ApplicationPath("api")
public classMyResourceConfig extends ResourceConfig {

    publicMyServicesResourceConfig() {
        register( new GZipEncoder() );
        register( JacksonFeature.class );
        addMyResources();
    }

    private void addMyResources() {
        register( Service1.class );
        register( Service2.class );
    }
}