杰克逊序列化为模板列表

时间：2017-06-07 16:19:03

标签： java json spring api jackson

我有一个这样的课程：

public class Garage<T> {
    private List<T> vehicles;

    public Garage() {
    }

    public Garage(List<T> vehicles) {
        this.vehicles = Collections.unmodifiableList(vehicles);
    }

    public List<T> getVehicles() {
        return vehicles;
    }
}

public class Car {
    private Type type;
    private Make make;
    private Model model;
    private String name;
}

public class Boat {
    private double weight;
    private Make make;
    private Model model;
    private String name;
}

这样的Spring API端点：

@RestController
public class CarController {
    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public ResponseEntity<List<Vehicles>> addCar(@RequestBody Garage<Car> cars) {
        //logic
    }
}

当我尝试传入一个如下所示的JSON输入时：

{
   "vehicles":[
      {
         "type":SEDAN,
         "make":HONDA,
         "model":ACCORD,
         "name":"My Awesome Car"
      },
      {
         "type":SUV,
         "make":HONDA,
         "model":CRV,
         "name":"My Awesome Car 2"
      }
   ]
}

我收到错误：

org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: No serializer found for class java.io.PushbackInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.http.converter.HttpMessageNotReadableException["cause"]->com.fasterxml.jackson.databind.JsonMappingException["location"]->com.fasterxml.jackson.core.JsonLocation["sourceRef"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class java.io.PushbackInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.http.converter.HttpMessageNotReadableException["cause"]->com.fasterxml.jackson.databind.JsonMappingException["location"]->com.fasterxml.jackson.core.JsonLocation["sourceRef"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:292) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:100) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:231) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:203) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:81) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:132) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver.doResolveHandlerMethodException(ExceptionHandlerExceptionResolver.java:380) ~[spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerMethodExceptionResolver.doResolveException(AbstractHandlerMethodExceptionResolver.java:59) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:136) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:74) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1193) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.web.servlet.TestDispatcherServlet.processHandlerException(TestDispatcherServlet.java:112) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1030) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) [tomcat-embed-core-8.5.6.jar:8.5.6]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [tomcat-embed-core-8.5.6.jar:8.5.6]
    at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:115) [spring-boot-1.5.0.RC1.jar:1.5.0.RC1]
    at org.springframework.boot.web.support.ErrorPageFilter.access$000(ErrorPageFilter.java:59) [spring-boot-1.5.0.RC1.jar:1.5.0.RC1]
    at org.springframework.boot.web.support.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:90) [spring-boot-1.5.0.RC1.jar:1.5.0.RC1]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:108) [spring-boot-1.5.0.RC1.jar:1.5.0.RC1]
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:155) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at net.api.controllers.CarControllerTest.test(CarControllerTest.java:46) [test-classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121]
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) [junit-4.12.jar:4.12]
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) [junit-4.12.jar:4.12]
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191) [spring-test-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137) [junit-4.12.jar:4.12]
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) [junit-rt.jar:na]
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51) [junit-rt.jar:na]
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242) [junit-rt.jar:na]
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70) [junit-rt.jar:na]
Caused by: com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class java.io.PushbackInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.http.converter.HttpMessageNotReadableException["cause"]->com.fasterxml.jackson.databind.JsonMappingException["location"]->com.fasterxml.jackson.core.JsonLocation["sourceRef"])
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:284) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.SerializerProvider.mappingException(SerializerProvider.java:1110) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.SerializerProvider.reportMappingProblem(SerializerProvider.java:1135) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:69) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:32) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:690) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:690) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:690) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:292) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1429) ~[jackson-databind-2.8.8.jar:2.8.8]
    at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:951) ~[jackson-databind-2.8.8.jar:2.8.8]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:285) ~[spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    ... 67 common frames omitted

但是如果我将api端点@RequestBody更改为@RequestBody Garage cars，那么Jackson反序列化就好了，但Garage对象包含HashMap个实例而不是Car个实例的列表。{{3} }

你如何解决这个问题？

2 个答案:

答案 0 :(得分：0)

将你的@RequestBody扩展到Garage并在你的类中实现Serializable

答案 1 :(得分：0)

我想出了这个问题。这是因为Car和Boat类没有默认的空构造函数。但是在添加之后：

public Car() {
}

有效

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