ModelMapper-无法将内部类转换为dto

Question

尝试将实体转换为dto时，使用modelmapper时出错。

我的java类是：

用户类：

@Data
@NoArgsConstructor
@Document("user")
public class User{
    @Id
    private String id;  
    private String lastname;    
    private String name;    
    private Rol rol;
    private City city;
    private App app;

}

Rol等级：

@Data
@NoArgsConstructor
@Document("rol")
public class Rol{
    @Id
    private String id;  
    private String name;    
    private String description; 
    private boolean state;

}

用户到类：

@Data
public class UserDTO {

    private String id;
    private String lastname;    
    private String name;    
    private RolDTO rol;

    @Data
    public class RolDTO {
        private String id;
        private String nombre;
    }

}

当我尝试映射用户时。类到UserDTO。当modelmapper出现下一个错误时初始化：

ModelMapper modelMapper = new ModelMapper();
modelMapper.map(user, UserDTO.class)

此外，我尝试使用此modelmapper配置：

ModelMapper modelMapper = new ModelMapper();
modelMapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.LOOSE)
                .setFieldMatchingEnabled(true)
                .setFieldAccessLevel(Configuration.AccessLevel.PACKAGE_PRIVATE)
                .setMethodAccessLevel(AccessLevel.PACKAGE_PRIVATE);
modelMapper.map(user, UserDTO.class)

错误：

Failed to instantiate instance of destination com.gh360.rest.dto.UserDTO$RolDTO. Ensure that com.gh360.rest.dto.UserDTO$RolDTO has a non-private no-argument constructor.

1 error] with root cause

java.lang.NoSuchMethodException: com.gh360.rest.dto.UserDTO$RolDTO.<init>()
at java.base/java.lang.Class.getConstructor0(Class.java:3427) ~[na:na]
    at java.base/java.lang.Class.getDeclaredConstructor(Class.java:2631) ~[na:na]
    at org.modelmapper.internal.MappingEngineImpl.instantiate(MappingEngineImpl.java:332) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingEngineImpl.createDestinationViaGlobalProvider(MappingEngineImpl.java:367) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingContextImpl.getParentDestination(MappingContextImpl.java:316) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingEngineImpl.setDestinationValue(MappingEngineImpl.java:226) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingEngineImpl.propertyMap(MappingEngineImpl.java:187) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingEngineImpl.typeMap(MappingEngineImpl.java:151) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingEngineImpl.map(MappingEngineImpl.java:114) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.internal.MappingEngineImpl.map(MappingEngineImpl.java:71) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.ModelMapper.mapInternal(ModelMapper.java:573) ~[modelmapper-2.3.0.jar:na]
    at org.modelmapper.ModelMapper.map(ModelMapper.java:406) ~[modelmapper-2.3.0.jar:na]
    at com.gh360.rest.mapper.ColaboradorMapper.toColaboradorBuscarDTO(ColaboradorMapper.java:29) ~[classes/:na]
    at com.gh360.rest.controller.ColaboradorController.buscarPorId(ColaboradorController.java:48) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:92) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
    at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]

如果RolDTO类是外部化的，模型映射器工作正常。我希望你能帮助我解决这个问题。

谢谢。

Answer 1

在UserDTO和RolDTO中使用@NoArgsConstructor。并在UserDTO之外创建RolDTO类。

Answer 2

强烈反对内部类（包括本地类和匿名类）的嵌套类序列化。当Java编译器编译某些构造时，例如内部类，它会创建合成构造；这些类、方法、字段和其他构造在源代码中没有相应的构造。