杰克逊杰森并没有这样的方法错误 [英] Jackson Json and no such method errors

问题描述

我正在尝试使用jackson序列化和反序列化POJO。从POJO到JSON的工作完美，但是朝另一个方向工作却没有。

I am trying to use jackson to serialize and deserialize a POJO. Going from POJO to JSON works perfectly but going the other direction does not.

我有一个POJO

public class Event {
  private String kind;

  public String getKind() {
    return kind;
  }

  public void setKind(String kind) {
    this.kind = kind;
  }
}

并运行和测试我运行包calendar.model ;

and to run and test I run package calendar.model;

Event event = new Event();
event.setKind("This is a kind");
String json = objectMapper.writeValueAsString(event); 
// RETURNS: "{\"kind\":\"This is a kind\"}"

objectMapper.readValue(json, Event.class);

抛出异常

java.lang.NoSuchMethodError: com.fasterxml.jackson.core.JsonParser.getValueAsString()Ljava/lang/String;
at com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:24)
at com.fasterxml.jackson.databind.deser.std.StringDeserializer.deserialize(StringDeserializer.java:11)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:375)
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:98)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:308)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2796)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:1942)
at calendar.controller.RootController.details(RootController.java:59)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:100)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:604)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:565)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)

我玩过所有可以让JSON到POJO工作但它不会。如果我从JSON映射到Map类型，它确实有效。

I have played with about all I can to get the JSON to POJO to work but it won't. It does work if I map from JSON to a Map type.

感谢您的帮助

这里是我的依赖项中的杰克逊的grep

here is a grep for jackson in my dependencies

± > mvn dependency:tree | grep jackson                                                                                                                       -I- 
[INFO] +- com.google.http-client:google-http-client-jackson2:jar:1.13.1-beta:compile
[INFO] |  \- com.fasterxml.jackson.core:jackson-core:jar:2.0.5:compile
[INFO] |  |  +- com.fasterxml.jackson.core:jackson-annotations:jar:2.1.1:compile
[INFO] |  |  +- com.fasterxml.jackson.dataformat:jackson-dataformat-xml:jar:2.1.1:compile
[INFO] |  |  |  +- com.fasterxml.jackson.core:jackson-databind:jar:2.1.1:compile
[INFO] |  |  |  +- com.fasterxml.jackson.module:jackson-module-jaxb-annotations:jar:2.1.0:compile

看起来除了jackson2之外没有其他版本的jackson。

It looks like there is no other version of jackson except for jackson2.

正在运行的完整方法是一个弹簧控制器方法。

The full method being run is a spring controller method.

@RequestMapping(value = "/")
  public Event root() throws IOException {
    Event event = new Event();
    event.setKind("This is a kind");
    String json = objectMapper.writeValueAsString(event);
    // RETURNS: "{\"kind\":\"This is a kind\"}"

    Event mapped = objectMapper.readValue(json, Event.class);
    return mapped;
  }

推荐答案

看起来问题是你得到的不兼容版本的 jackson-core 和 jackson-databind - jackson-core 2.0.5正在被拉in，但我相信至少需要2.1.0。

It looks like the problem is that you are getting incompatible versions of jackson-core and jackson-databind - jackson-core 2.0.5 is being pulled in, but I believe at least 2.1.0 is required.

异常的第一行告诉你它找不到方法 JsonParser.getValueAsString（），查看 2.0的API文档.5 ，该方法确实不存在。它看起来像是在中添加的2.1.0 。

The first line of the exception tells you that it can't find the method JsonParser.getValueAsString(), looking at the API docs for 2.0.5, that method indeed does not exist. It looks like it was added in 2.1.0.

因此，您需要修复依赖关系 - 最有可能是排除2.0.5并包括2.1.0。

So, you'll need to fix the dependencies - most likely by excluding 2.0.5 and including 2.1.0.

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