弹簧restTemplate NoClassDefFoundError

Question

当使用SpringrestTemplate对下面的代码使用NoClassDefFoundError时，在messageConverters.add(new MappingJackson2HttpMessageConverter());行中有一个

我错过了什么？

    RestTemplate restTemplate = new RestTemplate();
    List<HttpMessageConverter<?>> messageConverters = new   ArrayList<HttpMessageConverter<?>>();
    messageConverters.add(new MappingJackson2HttpMessageConverter());
    restTemplate.setMessageConverters(messageConverters);
    ResponseEntity<String> responseEntity = restTemplate
                .exchange(
                        "https://abc.stuff.com/abd",
                        HttpMethod.GET, requestEntity, String.class);

error:
exception in thread "main" java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/ObjectMapper
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.<init>(MappingJackson2HttpMessageConverter.java:62)

Answer 1

你可能失去了杰克逊的依赖关系。如果您使用的是maven，则可能需要添加以下内容。

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>${jackson.databind-version}</version>
</dependency>

还可以参考下面的链接来获取完整的依赖项集。

http://www.journaldev.com/2552/spring-restful-web-service-example-with-json-jackson-and-client-program

Answer 2

org.springframework.http.converter.json.MappingJackson2HttpMessageConverter类在spring中可用。所以请尝试在maven依赖项下面添加

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>4.1.1.RELEASE</version>
</dependency>