springmvc出现返回json数据类型的错误

访问Controller出现的错误如下：

java.lang.IllegalArgumentException: Unknown return value type [java.lang.Boolean]

at org.springframework.util.Assert.notNull(Assert.java:112)

at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:70)

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:690)

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)

at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)

at org.apache.coyote.http11.Http11ProtocolHttp11ConnectionHandler.process(Http11Protocol.java:588)atorg.apache.tomcat.util.net.JIoEndpointWorker.run(JIoEndpoint.java:489)

at java.lang.Thread.run(Unknown Source)

（记录一下自己的错误）

我这里是maven环境的，因为springmvc中默认是没有对象转换成json的转换器的，需要手动添加jackson依赖。所以首先要查看自己是否添加了jackson依赖，即在pom文件中引入jar包，如果已经添加了则要看是否添加了@ResponseBody注解。