Spring ModelMapper错误：控制器已经存在映射

Question

我通过DTO从表单中获取数据，并将其映射到Hibernate实体。我想跳过一个日期字段，因为传入的数据都是字符串，我需要将字符串字段转换为与其他字段分开的日期。其余字段将直接从传入DTO映射。对于第一个请求，该过程可以正常工作，但对于后续请求，会引发以下异常：

     1) A mapping already exists for com.ibm.calypso.entity.WmCompIdfn.setEffStartDate().

1 error
    at org.modelmapper.internal.Errors.toConfigurationException(Errors.java:250)
    at org.modelmapper.internal.TypeMapImpl.addMappings(TypeMapImpl.java:76)
    at org.modelmapper.internal.TypeMapStore.getOrCreate(TypeMapStore.java:110)
    at org.modelmapper.ModelMapper.addMappings(ModelMapper.java:93)
    at com.ibm.calypso.service.CompanyServiceImpl.updateIdentificationIdfn(CompanyServiceImpl.java:48)
    at com.ibm.calypso.controller.CompanyController.updateIdentificationIdfn(CompanyController.java:76)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:806)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:729)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doPut(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:651)
    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:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at com.ibm.calypso.filter.CORSFilter.doFilterInternal(CORSFilter.java:29)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2500)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2489)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$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)

这个错误已经被提出，但似乎没有人对此作出回应。

https://github.com/jhalterman/modelmapper/issues/103

我的代码结构与链接中的代码结构相似。

Answer 1

我知道这是一个老问题，但我也有同样的错误，但原因可能不同。下面是导致问题的代码：

private static final ModelMapper mapper = new ModelMapper();
{
    PropertyMap<SomeSourceClass, SomeTargetClass> map =
        new PropertyMap<SomeSourceClass, SomeTargetClass>() {
            @Override
            protected void configure() {
                // my configuration
            }
        };
    mapper.addMappings(map);
}

问题是ModelMapper是一个静态字段，但是每次创建这个类的新对象时，我的初始化都会发生，正确的代码使用静态初始化器来代替：

private static final ModelMapper mapper = new ModelMapper();
static {
    PropertyMap<SomeSourceClass, SomeTargetClass> map =
        new PropertyMap<SomeSourceClass, SomeTargetClass>() {
            @Override
            protected void configure() {
                // my configuration
            }
        };
    mapper.addMappings(map);
}

希望这能帮助有同样问题的人！

Answer 2

上述变通方法有效，但有以下条件：

if（typeMap==null）{modelMapper.addMappings（myPropertyMap）；}

With not null条件映射将永远不会添加到modelMapper。

Answer 3

我不确定你是否已经找到了解决办法。但为了克服这个问题，我做了一些变通。我在做modelMapper。在我的服务方法中添加映射（myPropertymap）。因此，它尝试为每个传入请求添加映射。我添加了下面的检查，以确保它仅在映射不存在时添加

// Before
modelMapper.addMappings(myPropertyMap);


// After
TypeMap<Source, Dest> typeMap = modelMapper.getTypeMap(Source.class, Dest.class);
if (typeMap == null) { // if not  already added
   modelMapper.addMappings(myPropertyMap);
}