Content type 'application/json;charset=UTF-8' not supported异常的解决过程

首先说一下当时的场景，其实就是一个很简单的添加操作，后台传递的值是json格式的，如下图

 ，后台对应的实体类，

@Data
@EqualsAndHashCode(callSuper = false)
public class Route implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * id
     */
    private String id;

    /**
     * 设备id
     */
    private String deviceId;

    /**
     * 路由地址
     */
    private String destNetwork;

    /**
     * 下一跳
     */
    private String nextHop;

    /**
     * 路由所属zone
     */
    private String zone;

    /**
     * 0：系统解析；1：明细路由；2：假路由
     */
    private String isReload;

    /**
     * nat路由
     */
    private String isNatDummyRoute;

    private String createTime;

    /**
     * 是否禁用，主要适用于系统解析路由
     */
    private String isDisabled;

    @TableField(exist = false)
    private Device device;

    /**
     * 路由转化后的对象
     */
    @TableField(exist = false)
    private IpAddr ipAddr;
}

后台对应的Controller中的代码

@RequestMapping(value = "add",method = RequestMethod.POST)
    public R add(@RequestBody Route route){

            String deviceIp = route.getDeviceId();
            Device device = deviceService.getByIp(deviceIp);
            Date date = new Date();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            String dateStr = sdf.format(date);
            route.setDeviceId(device.getId());
            route.setIsDisabled("0");
            route.setCreateTime(dateStr);
            routeService.save(route);
        return R.success();
    }

，看代码可知，页面传递到后台的值应该能直接转成实体类Route对应的字段。但是并没有，报错信息是如下：

2020/09/28-10:52:00 WARN [http-nio-8999-exec-6] MappingJackson2HttpMessageConverter - Failed to evaluate Jackson deserialization for type [[simple type, class com.interact.firewall.base.biz.entity.Route]]: com.fasterxml.jackson.databind.JsonMappingException: Conflicting setter definitions for property "parent": com.interact.firewall.core.bean.service.Service#setParent(1 params) vs com.interact.firewall.core.bean.service.Service#setParent(1 params)
2020/09/28-10:52:00 WARN [http-nio-8999-exec-6] MappingJackson2HttpMessageConverter - Failed to evaluate Jackson deserialization for type [[simple type, class com.interact.firewall.base.biz.entity.Route]]: com.fasterxml.jackson.databind.JsonMappingException: Conflicting setter definitions for property "parent": com.interact.firewall.core.bean.service.Service#setParent(1 params) vs com.interact.firewall.core.bean.service.Service#setParent(1 params)
2020/09/28-10:52:00 ERROR [http-nio-8999-exec-6] GlobalExceptionHandler - 捕获到Exception异常
org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'application/json;charset=UTF-8' not supported
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:225)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:158)
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:131)
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

于是我就按照这个异常信息去排查，

有人说是缺少依赖。但是并没有解决

有人说是字段没有映射对，就是说页面传递到后台的值跟实体类对应不上，但是我反复比对没有问题。

之前实体类中还写了一部分处理数据的方法，我也进行删除进行测试还是不行。

后来请教同事，同事也怀疑是实体类的问题，于是重新建了一个实体类，只要数据库的字段，不是数据库中的字段进行删除，结果可以了，于是继续排查，确认到底是哪个地方引起的，最终确认了，是因为实体类中引用了一个对象。将引用的这个对象删掉就没问题了，但是我们想了一下，其他的实体类也有因为需要关联查询直接引其他对象的，但是却没有出问题。为什么单单这个出问题呢。

其实报错中已经有提示了，在异常信息上边有两行警告代码：

Failed to evaluate Jackson deserialization for type [[simple type, class com.interact.firewall.base.biz.entity.Route]]: com.fasterxml.jackson.databind.JsonMappingException: Conflicting setter definitions for property "parent": com.interact.firewall.core.bean.service.Service#setParent(1 params) vs com.interact.firewall.core.bean.service.Service#setParent(1 params)

说的其实是序列化相关的问题，后来我们查看了一下在Route中引用的对象，确实，并没有实现Serializable 这个接口，导致这个问题的发生，但是这个对象又必须引用，那怎么办呢？想了一下，是不是有个注解能够忽略反序列化字段呢？于是查了一下，果然有

JsonIgnore这个注解就可以将被标记属性忽略反序列化功能。

总结一下：其实这个问题的根本原因就是实体类中引用了一个没有实现实现Serializable 接口的对象，无法被反序列化，只需要在这个对象上添加@JsonIgnore这个注解即可。对了 一直在说没有实现Serializable接口的对象是实体类中最后一个Ipaddr那个对象。

/**
     * 路由转化后的对象
     */
    @TableField(exist = false)
    @JsonIgnore
    private IpAddr ipAddr;