Can not construct instance of java util LinkedHashMap no St

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出现这个问题是由于
参数传入的是一个String类型 无法转换为Map

$.ajax({              type:'POST',              url:hostUrl,              dataType:'json',              contentType:'application/json',              async:false,      // 重点在这里              data:JSON.stringify(‘{"parentId":"0"}’),              success: function(json) {                  if(json.success){              },            error: function(XMLHttpRequest, textStatus, errorThrown) {             }          });
  
  
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前台发送请求的时候 由于传来的

  data:JSON.stringify(‘{"parentId":"0"}’), 前后加了一个‘’导致这个不是一个合法的json对象，而是一个string了  解决办法    data:JSON.stringify({"parentId":"0"}),
  
  
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org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not construct instance of java.util.LinkedHashMap: no String-argument constructor/factory method to deserialize from String value ('{"parentId":"0","delflag":"0","sidx":"sort"}') at [Source: java.io.PushbackInputStream@5231d0e2; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of java.util.LinkedHashMap: no String-argument constructor/factory method to deserialize from String value ('{"parentId":"0","delflag":"0","sidx":"sort"}') at [Source: java.io.PushbackInputStream@5231d0e2; line: 1, column: 1]    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:228)    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:213)    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:197)    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:149)    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:127)    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161)    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114)    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:123)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:105)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:208)    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177)    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.session.web.http.SessionRepositoryFilter.doFilterInternal(SessionRepositoryFilter.java:164)    at org.springframework.session.web.http.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:80)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.cloud.sleuth.instrument.web.TraceFilter.doFilter(TraceFilter.java:150)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:107)    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)    at org.apache.catalina.core.StandardContextValve.__invoke(StandardContextValve.java:108)    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java)    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784)    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802)    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410)    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)    at java.lang.Thread.run(Thread.java:748)Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of java.util.LinkedHashMap: no String-argument constructor/factory method to deserialize from String value ('{"parentId":"0","delflag":"0","sidx":"sort"}') at [Source: java.io.PushbackInputStream@5231d0e2; line: 1, column: 1]    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:261)    at com.fasterxml.jackson.databind.DeserializationContext.instantiationException(DeserializationContext.java:1420)    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1011)    at com.fasterxml.jackson.databind.deser.ValueInstantiator._createFromStringFallbacks(ValueInstantiator.java:366)    at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:307)    at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:345)    at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:27)    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3789)    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2913)    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:225)    ... 84 common frames omitted
  
  
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分享一下我老师大神的人工智能教程。零基础！通俗易懂！风趣幽默！还带黄段子！希望你也加入到我们人工智能的队伍中来！https://blog.youkuaiyun.com/jiangjunshow