Deserialise Json到嵌套pojo的

Question

似乎有一些类似的问题，但我似乎无法找到答案？

我想解析jqGrid过滤器属性在控制器中返回的json。为了得到它的工作，我以非常笨拙的方式来完成它，尽管一旦我有了它，我希望能够继续下一步，并将它作为一个RequestBody传递给Spring，并让它处理这些事情。现在，如果可能，我希望以这种方式工作？似乎它应该只是工作，所以也许我犯了一个愚蠢的错误？

JSON样本

{"groupOp":"AND","rules":[{"field":"accountName","op":"cn","data":"E"},{"field":"accountRef","op":"cn","data":"E"}]} 

我做了2层快的POJO，试图deserialise数据

@SuppressWarnings("unused") 
private class Filter { 

    private String groupOp; 
    private List<Rule> rules; 

    public String getGroupOp() { 
     return groupOp; 
    } 
    public void setGroupOp(String groupOp) { 
     this.groupOp = groupOp; 
    } 

    public List<Rule> getRules() { 
     return rules; 
    } 
    public void setRules(List<Rule> rules) { 
     this.rules = rules; 
    } 

} 

private class Rule { 

     private String field; 
     private String op; 
     private String data; 

     public String getField() { 
      return field; 
     } 
     public void setField(String field) { 
      this.field = field; 
     } 

     public String getOp() { 
      return op; 
     } 
     public void setOp(String op) { 
      this.field = op; 
     } 

     public String getData() { 
      return data; 
     } 
     public void setData(String data) { 
      this.data = data; 
     } 
} 

JSON字符串在字符串参数调用过滤器有这个很基本的代码去反序列化它

byte[] jsonData = filter.getBytes(); 

ObjectMapper objectMapper = new ObjectMapper();   
Filter f = objectMapper.readValue(jsonData, Filter.class); 

我对样品的阅读是，这是非常基础和严重的wr但应该做这项工作。相反，我得到一个错误...

我已经复制了完整的错误，这可能是过度的？谁能告诉我我要去哪里？

com.fasterxml.jackson.databind.JsonMappingException: Can not construct 
instance of com.app.AppController$Filter: no String-argument constructor/factory method to deserialize from String value (' {"groupOp":"AND","rules":[{"field":"accountName","op":"cn","data":"E"},{"field":"accountRef","op":"cn","data":"E"}]}') 
at [Source: [[email protected]; line: 1, column: 1] 
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:270) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.DeserializationContext.instantiationException(DeserializationContext.java:1456) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1012) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.deser.ValueInstantiator._createFromStringFallbacks(ValueInstantiator.java:370) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:315) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1290) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:159) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:150) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3798) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2929) ~[jackson-databind-2.8.7.jar:2.8.7] 
    at com.app.AppController.downloadAccounts(AppController.java:580) ~[classes/:na] 
    at com.app.AppController$$FastClassBySpringCGLIB$$6a077f1a.invoke(<generated>) ~[classes/:na] 
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720) ~[spring-aop-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655) ~[spring-aop-5.0.0.M3.jar:5.0.0.M3] 
    at com.app.AppControllerController$$EnhancerBySpringCGLIB$$8ff0ac7a.downloaAccounts(<generated>) ~[classes/:na] 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_101] 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_101] 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_101] 
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_101] 
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:220) ~[spring-web-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134) ~[spring-web-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116) ~[spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) ~[spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:964) [spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:856) [spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:841) [spring-webmvc-5.0.0.M3.jar:5.0.0.M3] 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) [spring-web-5.0.0.M3.jar:5.0.0.M3] 
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.0.M3.jar:5.0.0.M3] 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) [tomcat-embed-core-7.0.47.jar:7.0.47] 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_101] 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_101] 
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_101] 

Answer 1

我看到无论Filter和Rule是私有的内部类。这就是为什么杰克逊无法创建它们的实例。尝试使它们成为公共嵌套类，即将它们声明为public static类，或将它们移动到单独的源文件。

我也注意到在堆栈跟踪中，您的字节数组在开始时包含单引号，而在结尾处包含另一个引号。你应该删除它们，第一个字符应该是左大括号，最后一个是大括号。否则，readValue就像它是一个字符串一样。