使用Spring4时， 运行时出现找不到MappingJacksonHttpMessageConverter的情况

Posted 2020-10-01 干不好测试的程序员不是一个好工程师!

启动项目报错：

[org.springframework.web.context.ContextLoader]Context initialization failed
org.springframework.beans.factory.BeanCreationException: 
      Error creating bean with name ‘org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter#0‘ 
... ...
Caused by: org.springframework.beans.factory.CannotLoadBeanClassException: 
    Cannot find class [org.springframework.http.converter.json.MappingJacksonHttpMessageConverter] for bean with name ‘org.springframework.http.converter.json.MappingJacksonHttpMessageConverter#2aa148c0‘ 
... ...
Caused by: java.lang.ClassNotFoundException: org.springframework.http.converter.json.MappingJacksonHttpMessageConverter
    ... ...

原因是Spring 3.x 和4.X处理JSON的一个类不一样，而这个东西又配置在xml文件中，所以编译时又无法发现

spring3.x是org.springframework.http.converter.json.MappingJacksonHttpMessageConverter

spring4.x是org.springframework.http.converter.json.MappingJackson2HttpMessageConverter

1. 查找替换所有XML中名字

2. 同时加入最新的FastJackson依赖

<dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.8.5</version>
</dependency>
<dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.8.5</version>
</dependency>
<dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>2.8.5</version>
</dependency>

问题解决！