解决办法：springmvc json类型转换错误

　　这篇文章主要介绍了springmvc json类型转换错误解决方案,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

　　在用springmvc做json数据时，返回时，提示类型转换错误（http://nk.xcmnyy.com）

　　如下，

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org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalArgumentException: No converter found for return value of type: class cn.taotao.bean.Role   org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)   org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)   javax.servlet.http.HttpServlet.service(HttpServlet.java:634)   org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)   javax.servlet.http.HttpServlet.service(HttpServlet.java:741)   org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)   org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)   org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)   org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61)   org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)   org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)   org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)   org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)   org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)   org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)   org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)   org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)   org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383)   org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)   org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)   org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:347)   org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:263) Root Cause   java.lang.IllegalArgumentException: No converter found for return value of type: class cn.taotao.bean.Role   org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:187)   org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:174)   org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:81)   org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:113)   org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:854)   org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:765)   org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)   org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)   org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)   org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)   org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)   javax.servlet.http.HttpServlet.service(HttpServlet.java:634)   org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)   javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

　　解决办法为（http://www.0834xcjl.com）

　　在pom中添加，只要添加上这两个jackson的支持，就可以了。

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<dependency>    <groupId>com.fasterxml.jackson.core</groupId>    <artifactId>jackson-core</artifactId>    <version>2.8.8</version> </dependency>  <!-- 返回json字符串的支持 -->     <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->     <dependency>       <groupId>com.fasterxml.jackson.core</groupId>       <artifactId>jackson-databind</artifactId>       <version>2.8.8</version>     </dependency>

　　在springmvc的controller的方法为，如下（http://3g.0834jlnk.com）

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@RequestMapping("/getRole/{id}")   @ResponseBody   public Role getRole(@PathVariable("id") Integer id ) {     Role roleById = roleService.getRoleById(id);     return roleById;   }

　　若仍不能解决，可以在springmvc配置文件中进行如下配置(待验证)

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<mvc:annotation-driven>   <mvc:message-converters>     <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>      <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>   </mvc:message-converters> </mvc:annotation-driven>