dubbo rest返回值異常Incompatible types: declared root type

 1 2018-08-28 17:26:02,208 [http-bio-9090-exec-1][][][][][] ERROR com.wjs.member.plugin.intercepter.ServiceExecutionInterceptor 116 - Incompatible types: declared root type ([map type; class java.util.Map, [simple type, class java.lang.String] -> [collection type; class java.util.List, contains [simple type, class com.wjs.member.clientVo.deduct.DeductCurVo]]]) vs com.wjs.common.web.JsonResult
 2 org.codehaus.jackson.map.JsonMappingException: Incompatible types: declared root type ([map type; class java.util.Map, [simple type, class java.lang.String] -> [collection type; class java.util.List, contains [simple type, class com.wjs.member.clientVo.deduct.DeductCurVo]]]) vs com.wjs.common.web.JsonResult
 3     at org.codehaus.jackson.map.ser.StdSerializerProvider._reportIncompatibleRootType(StdSerializerProvider.java:687) ~[jackson-mapper-asl-1.9.13.jar:1.9.13]
 4     at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:647) ~[jackson-mapper-asl-1.9.13.jar:1.9.13]
 5     at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:271) ~[jackson-mapper-asl-1.9.13.jar:1.9.13]
 6     at org.codehaus.jackson.map.ObjectWriter.writeValue(ObjectWriter.java:325) ~[jackson-mapper-asl-1.9.13.jar:1.9.13]
 7     at org.codehaus.jackson.jaxrs.JacksonJsonProvider.writeTo(JacksonJsonProvider.java:557) ~[jackson-jaxrs-1.9.13.jar:1.9.13]
 8     at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.writeTo(AbstractWriterInterceptorContext.java:137) ~[resteasy-jaxrs-3.6.0.Final.jar:3.6.0.Final]
 9     at org.jboss.resteasy.core.interception.ServerWriterInterceptorContext.writeTo(ServerWriterInterceptorContext.java:61) ~[resteasy-jaxrs-3.6.0.Final.jar:3.6.0.Final]
10     at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:124) ~[resteasy-jaxrs-3.6.0.Final.jar:3.6.0.Final]
11     at com.wjs.member.plugin.intercepter.RestContextInteceptor.aroundWriteTo(RestContextInteceptor.java:77) ~[com.wjs.dubbo-demo.service-180830-SNAPSHOT.jar:na]
12     at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:129) ~[resteasy-jaxrs-3.6.0.Final.jar:3.6.0.Final]
13     at org.jboss.resteasy.core.ServerResponseWriter.lambda$writeNomapResponse$2(ServerResponseWriter.java:140) ~[resteasy-jaxrs-3.6.0.Final.jar:3.6.0.Final]
14     at org.jboss.resteasy.core.interception.ContainerResponseContextImpl.filter(ContainerResponseContextImpl.java:395) ~[resteasy-jaxrs-3.6.0.Final.jar:3.6.0.Final]

在封裝dubbo的rest請求返回值的時候，對於List和Map返回值，會出現如上錯誤。其緣由是resteasy的AbstractWriterInterceptorContext調用JSON序列化的時候，傳入的entity和genericType不一致，

codehaus.jackson的StdSerializerProvider類對entity和genericType比對不一致，並報錯。

 

 

解決辦法，在封裝返回值的時候，修改WriterInterceptorContext的GenericType類型，以下代碼紅色部分。

 1 @Override
 2     public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException {
 3 
 4 //        System.err.println("進入結果處理——aroundWriteTo");
 5 //        針對須要封裝的請求對結構進行封裝處理。這裏須要注意的是對返回類型已是封裝類（好比：異常處理器的響應可能已是封裝類型）時要忽略掉。
 6         Object originalObj = context.getEntity();
 7         String wrapTag = context.getProperty("Not-Wrap-Result") == null ? "" : context.getProperty("Not-Wrap-Result").toString(); // 客戶端顯示提醒不要對返回值進行封裝
 8         Boolean wraped = originalObj instanceof JsonResult; // 已經被封裝過了的，不用再次封裝
 9         if (StringUtils.isBlank(wrapTag) && !wraped){
10             JsonResult<Object> result = new JsonResult<>(true, "執行成功");
11             result.setData(context.getEntity());
12             context.setEntity(result);
13 //            如下兩處set避免出現Json序列化的時候，對象類型不符的錯誤
14 context.setType(result.getClass()); 15 context.setGenericType(result.getClass().getGenericSuperclass()); 16         }
17         context.proceed();
18         
19     }