java - 使用 jackson databind 解析 yaml 会导致 MismatchedInputException

Question

我试图读取的yaml格式如下

- name: storage
  scm: git
  src: git+https://bitbucket.org/cer/linux_storage_jenkins.git
  version: '5'
- name: linux_jenkins
  scm: git
  src: git+https://bitbucket.org/cer/linux_jenkins.git
  version: '8'

我的模型很简单

public class Requirementsyml {
    //setter and getter in place
    private List<Requirement> items;
}

public class Requirement {
    private String name;
    private String scm;
    private String src;
    private String version;
}

我正在尝试读取 yaml 内容，如下所示:

ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
Requirementsyml req = mapper.readValue(yaml_file_content, Requirementsyml.class);

但是我收到以下异常 com.fasterxml.jackson.databind.exc.MismatchedInputException:无法从 START_ARRAY token 中反序列化 Demandyml 实例

由于模型有一个列表，我认为输入不应不匹配。 我尝试将 yaml 文件提供为 java 文件对象，而不是其内容作为字符串。结果保持不变。我错过了什么？

Answer 1

yaml 结构应该有 items 数组/列表

items:
- name: storage
  scm: git
  src: git+https://bitbucket.org/cer/linux_storage_jenkins.git
  version: '5'
- name: linux_jenkins
  scm: git
  src: git+https://bitbucket.org/cer/linux_jenkins.git
  version: '8'

或者您可以将其视为需求列表，无需更改 yaml

@Test
void test() throws IOException {
    ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
    List<Requirement> requirements = mapper.readValue(new File("src/test/resources/requirements.yml"), new TypeReference<List<Requirement>>() {});
    assertEquals(2, requirements.size());
}

还要确保 Requirement 和其他类没有参数构造函数，否则在 ObjectMapper 上设置适当的标志