java - Jackson、Retrofit、JodaTime 反序列化

Question

我正在使用这三个库:retrofit、jackson 和 jodatime，当它来 self 的 rest api 时，我正在尝试反序列化我的对象，但我不知道如何解决这个问题，这里是 json由 rest api 返回:

{
    "establishment": "Gold Ball Confraria",
    "idCardPayment": 0,
    "paymentDate": "/Date(1461208761970+0000)/",
    "total": 10
}

这是我试图反序列化我的对象的类:

public class PaymentHistoryItemApiResult {

    @JsonProperty("total")
    private double totalValue;
    @JsonProperty("establishment")
    private String establishmentName;
    @JsonDeserialize(using = DateTimeDeserializer.class)
    private DateTime paymentDate;
    private long idCardPayment;

    public PaymentHistoryItemApiResult() {

    }

    public PaymentHistoryItemApiResult(double totalValue, String establishmentName, DateTime paymentDate, long idCardPayment) {
        this.totalValue = totalValue;
        this.establishmentName = establishmentName;
        this.paymentDate = paymentDate;
        this.idCardPayment = idCardPayment;
    }
... getters/setters

}

API 端点:

    @GET("User.svc/{idUser}/payment/history")
    Call<PaymentHistoryItemApiResult> getPaymentHistory(@Path("idUser") long idUser);

如何从单元测试中调用它:

@Test
public void getPaymentHistoryTest(){

    Response<PaymentHistoryItemApiResult> info = null;
    try {
        info = UserRequester.userRequester.getPaymentHistory(153).execute();

        PaymentHistoryItemApiResult res = info.body();
        Assert.assertNotNull(res);

    } catch (IOException e) {
        e.printStackTrace();
    }

}

错误:

com.fasterxml.jackson.databind.JsonMappingException: Class com.fasterxml.jackson.datatype.joda.deser.DateTimeDeserializer has no default (no arg) constructor
 at [Source: java.io.InputStreamReader@525b461a; line: 1, column: 1]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:251)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:269)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer(DeserializerCache.java:244)
    at com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer(DeserializerCache.java:142)
    at com.fasterxml.jackson.databind.DeserializationContext.findRootValueDeserializer(DeserializationContext.java:477)
    at com.fasterxml.jackson.databind.ObjectReader._findRootDeserializer(ObjectReader.java:1813)
    at com.fasterxml.jackson.databind.ObjectReader._bindAndClose(ObjectReader.java:1570)
    at com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:1183)
    at retrofit2.converter.jackson.JacksonResponseBodyConverter.convert(JacksonResponseBodyConverter.java:32)
    at retrofit2.converter.jackson.JacksonResponseBodyConverter.convert(JacksonResponseBodyConverter.java:23)
    at retrofit2.ServiceMethod.toResponse(ServiceMethod.java:116)
    at retrofit2.OkHttpCall.parseResponse(OkHttpCall.java:211)
    at retrofit2.OkHttpCall.execute(OkHttpCall.java:174)
    at br.com.soutsapp.user.souts.WCFClientTest.getPaymentHistoryTest(WCFClientTest.java:96)
    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.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:78)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:212)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:68)
    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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
Caused by: java.lang.IllegalArgumentException: Class com.fasterxml.jackson.datatype.joda.deser.DateTimeDeserializer has no default (no arg) constructor
    at com.fasterxml.jackson.databind.util.ClassUtil.createInstance(ClassUtil.java:594)
    at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.deserializerInstance(DefaultDeserializationContext.java:234)
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory.findDeserializerFromAnnotation(BasicDeserializerFactory.java:1772)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.constructSettableProperty(BeanDeserializerFactory.java:728)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.addBeanProps(BeanDeserializerFactory.java:506)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.buildBeanDeserializer(BeanDeserializerFactory.java:228)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:143)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:406)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:352)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:264)
    ... 38 more

在此先致谢，如有任何帮助，我们将不胜感激。

Answer 1

第一 View 分析:

您的代码中存在一些问题。那你提供的时间"/Date(1461208761970+0000)/"看起来不熟悉。您也有一些代码问题。您的构造函数无法与 joda 构造函数正确对话

根本原因:

您的问题:

com.fasterxml.jackson.databind.JsonMappingException: Class com.fasterxml.jackson.datatype.joda.deser.DateTimeDeserializer has no default (no arg) constructor

是从您的代码生成的:

 at br.com.soutsapp.user.souts.WCFClientTest.getPaymentHistoryTest(WCFClientTest.java:96)

问题分析:

将值反序列化为 org.joda.time.DateTime你必须定义 @JsonDeserialize因为 jackson 无法从 org.joda.time.DateTime 中找出使用什么方法/构造函数从字符串值初始化它。

解决方案 - 1:

您需要使用序列化和反序列化。您应该检查 jar 可用性并将读取类型设置为 JSON。

您可以按照以下 3 个步骤操作。

1. 您需要使用序列化和反序列化。您的日期格式应该类似于 JsonFormat。

代码将是

@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss")
@JsonSerialize(using = DateTimeSerializer.class)
@JsonDeserialize(using = DateTimeDeserializer.class)
private DateTime paymentDate;

1. 确保您在类路径上有 jackson-datatype-joda .

2. 更改 SSM 配置以默认使用 JSON 格式(在 defaultMemcachedClient 定义):

   <property name="defaultSerializationType" value="JSON" />

资源链接:

https://github.com/ragnor/simple-spring-memcached/issues/41

---

解决方案 - 2:

您也可以添加另一个构造函数。这可能会影响。

 public PaymentHistoryItemApiResult() {
        super();
   }

资源链接:以下 2 个链接包含更多错误分析和解决方案

1. Jackson Exceptions – Problems and Solutions
2. Jackson – JsonMappingException (No serializer found for class)

---

另一个解决方案:

如果你不想使用反序列化那么你可以按照细节:

@JsonDeserialize期望一个 JsonDeserializer使用无参数构造函数。最新版本的 DateTimeDeserializer 没有这样的构造函数。

如果您已修复格式，即。 yourTimestamp 应该只是一个时间戳，然后你可以简单地注册 JodaModule与 ObjectMapper .它将在内部对 DateTime 字段使用 DateTimeDeserializer。 您可以去掉 @JsonDeserialize 注释。

mapper.registerModule(new JodaModule());

您需要添加 jackson-datatype-joda图书馆。

资源链接:

1. joda.time.DateTime deserialization error

For null value serialization and deserialization

如果不想序列化空值，可以在序列化时使用如下设置:

objectMapper.setSerializationInclusion(Include.NON_NULL);

对于反序列化，Jackson 理想情况下应该能够处理序列化输出中的空值。

归功于@ jackall

或者您也可以在类里面使用注释。

@JsonIgnoreProperties(ignoreUnknown = true)
@JsonInclude(Include.NON_NULL)