Question

将JSON数据映射到POJO类的问题。 Customer Class有两个字段“customerId，isTrue。”我正在为每个字段使用JacksonMixInAnnotations。

JUnit Test在没有JSON的第一部分（{\“customer \”：“）的情况下没有问题。如果包含它则失败，（对于customer.getCustomerId（）为null）。

由于

@Test
public void test() {
    mockServer.expect(requestTo("..."))
        .andExpect(method(GET))
        .andRespond(withSuccess(str, MediaType.APPLICATION_JSON));
    Customer customer = api.operations().getCustomer();
    assertEquals("foo", customer.getCustomerId());
    assertEquals("TRUE"),customer.isTrue());
}

String str = "{ \"customer\": { \"customer-id\": \"foo\",\"is-true\": \"TRUE\" }}";

@Override
protected MappingJacksonHttpMessageConverter getJsonMessageConverter() {
    MappingJacksonHttpMessageConverter converter = super.getJsonMessageConverter();
    objectMapper = new ObjectMapper();
    objectMapper.registerModule(new TestModule());
    converter.setObjectMapper(objectMapper);
    return converter;
}

如果我向POJO添加“customer”字段，则会出现以下错误：

org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Can not deserialize instance of java.lang.String out of START_OBJECT token
 at [Source: java.io.ByteArrayInputStream@1d8835d; line: 1, column: 3]; nested exception is org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token
 at [Source: java.io.ByteArrayInputStream@1d8835d; line: 1, column: 3]
    at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.readJavaType(MappingJacksonHttpMessageConverter.java:169)
    at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.read(MappingJacksonHttpMessageConverter.java:161)
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:94)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:491)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:460)
    at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:228)
    at org.springframework.social.test.api.impl.CustomerTemplate.getCustomer(CustomerTemplate.java:24)
    at org.springframework.social.test.api.impl.CustomerTemplateTest.getCustomer_current_user(CustomerTemplateTest.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token
 at [Source: java.io.ByteArrayInputStream@1d8835d; line: 1, column: 3]
    at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
    at org.codehaus.jackson.map.deser.StdDeserializationContext.mappingException(StdDeserializationContext.java:219)
    at org.codehaus.jackson.map.deser.std.StringDeserializer.deserialize(StringDeserializer.java:44)
    at org.codehaus.jackson.map.deser.std.StringDeserializer.deserialize(StringDeserializer.java:13)
    at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
    at org.codehaus.jackson.map.deser.BeanDeserializer._deserializeUsingPropertyBased(BeanDeserializer.java:905)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObjectUsingNonDefault(BeanDeserializer.java:739)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:683)
    at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2732)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1923)
    at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.readJavaType(MappingJacksonHttpMessageConverter.java:166)
    ... 31 more

Answer 1

查看@JsonRootName annotation（将其添加到您的Customer.class）并使用方法DeserializationFeature在UNWRAP_ROOT_VALUE上启用ObjectMapper enable(DeserializationFeature feature)

Jackson Object Mapper和JSON

1 个答案: