如何在Spring Boot中定义自定义对象映射器而不影响Spring Boot的默认对象映射器？

问题描述 投票：0回答：2

考虑一个Spring Boot应用程序：

Model Class 1

package com.example.demo.model;

public class **BigClass** {

  private Integer id;
  private String name;
  // Getters Setters are trimmed for brevity
}

Model Class 2

package com.example.demo;

public class **BigClass** {

  private Integer id;
  private String name;
  private Boolean isPresent;
  // Getters Setters are trimmed for brevity 
}

Rest Controller

我正在尝试将一个包含额外成员变量的“ BigClass”对象映射到另一个包含较少成员变量的“ BigClass”对象。

@RestController
public class HelloController {

  @Autowired
  private ObjectMapper objectMapper;

  @GetMapping("/hello")
  public void sayHello() {
    BigClass bg = new BigClass();
    bg.setId(1234);
    bg.setName("Demo");
    bg.setIsPresent(true);
    com.example.demo.model.BigClass bigClass =
        objectMapper.convertValue(bg, com.example.demo.model.BigClass.class);

  }
}

此代码运行得很好，因为Spring Boot默认对象映射器的规范为“ DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES：已禁用”]]

但是当我更改Main类并按如下所示添加自定义对象映射器时

Main Class

    @SpringBootApplication
    public class DemoApplication {

      @Bean("myCustomBean")
      public ObjectMapper customObjectMapper() {
        return new ObjectMapper();
      }

      public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
      }

  }

上面的Rest Controller代码停止工作，给出以下错误：
curl "localhost:8081/hello"


 com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "isPresent" (class com.example.demo.model.BigClass), not marked as ignorable (2 known properties: "id", "name"])
 at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.example.demo.model.BigClass["isPresent"])
    at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:61) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnknownProperty(DeserializationContext.java:840) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:1206) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1592) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownVanilla(BeanDeserializerBase.java:1570) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:294) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:3917) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:3853) ~[jackson-databind-2.10.2.jar:2.10.2]
    at com.example.demo.HelloController.sayHello(HelloController.java:21) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_242]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_242]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_242]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_242]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1639) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_242]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_242]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.31.jar:9.0.31]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_242]

我的问题
：
  1. 为什么我的对象映射器bean（具有唯一的Bean名称）影响了现有的默认spring boot对象映射器的功能，所以>
  2. 在这种情况下，如果我无法使用默认的对象映射器来控制遗留代码，那么在不破坏遗留代码的情况下定义自定义对象映射器的选择有哪些？注意：我无法以任何方式更改旧版代码。

    3. 任何帮助将不胜感激。

考虑一个Spring Boot应用程序：Model Class 1包com.example.demo.model;公共类** BigClass ** {私有整数ID；私有字符串名称； // Getters的Getters被修整为...

java spring spring-boot objectmapper
2个回答
0
投票

创建对象映射器时，我们需要如下所示配置其属性

@Bean
public ObjectMapper objectMapper() {
    return new ObjectMapper().setSerializationInclusion(JsonInclude.Include.NON_NULL)
            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES , 
       false);
}
0
投票

Spring Jackson自动配置使用@ConditionalOnMissingBean创建默认的ObjectMapper。这意味着只有在不存在相同类型的bean时才创建它。因此，通过创建自己的ObjectMapper bean，Spring自动配置不会创建一个。

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