SnakeYaml“无法找到属性错误” [英] SnakeYaml "Unable to find property error"

问题描述

以下是我的config.yml的一部分：

Here is part of my config.yml:

#Authenctication
AuthenticationConfig:
  AuthencticationType: LDAP
  LDAPConfig:
     LDAPUrl: ldap://localhost:389
     ConnectionType: simple
     LDAPSecurityConfig:
        RootDN: cn=manager,dc=maxcrc,dc=com
        RootPassword: secret
        UserSearchDN: ou=People,dc=maxcrc,dc=com
        GroupdSearchDB: ou=Groups,dc=maxcrc,dc=com

我有一个用于解析的类：

I have a class used for parsing:

public class YamlConfiguraiton {
    private AuthenticationConfiguration AuthenticationConfig;

    public void setAuthenticationConfig(AuthenticationConfiguration AuthenticationConfig) {
        this.AuthenticationConfig = AuthenticationConfig;
    }

    public AuthenticationConfiguration getAuthenticationConfig() {
        return this.AuthenticationConfig;
    }
}

但是，当我运行时

try(InputStream in = new FileInputStream(new File(ymalPath))) {
            yamlConfig = yaml.loadAs(in, YamlConfiguraiton.class);
        } catch (IOException e) {
            e.printStackTrace();
        }

发生以下错误：

Exception in thread "main" Cannot create property=AuthenticationConfig for JavaBean=com.ibm.entity.matching.common.bootstrap.YamlConfiguraiton@e7860081
 in 'reader', line 2, column 1:
    AuthenticationConfig:
    ^
Unable to find property 'AuthenticationConfig' on class: com.ibm.entity.matching.common.bootstrap.YamlConfiguraiton
 in 'reader', line 3, column 4:
       AuthencticationType: LDAP
       ^

    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:270)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:149)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:309)
    at org.yaml.snakeyaml.constructor.BaseConstructor.constructObjectNoCheck(BaseConstructor.java:204)
    at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:193)
    at org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:159)
    at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:146)
    at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:524)
    at org.yaml.snakeyaml.Yaml.loadAs(Yaml.java:518)
    at com.ibm.entity.matching.bootstrap.EntityMatching.boot(EntityMatching.java:55)
    at com.ibm.entity.matching.bootstrap.EntityMatching.main(EntityMatching.java:35)
Caused by: org.yaml.snakeyaml.error.YAMLException: Unable to find property 'AuthenticationConfig' on class: com.ibm.entity.matching.common.bootstrap.YamlConfiguraiton
    at org.yaml.snakeyaml.introspector.PropertyUtils.getProperty(PropertyUtils.java:159)
    at org.yaml.snakeyaml.introspector.PropertyUtils.getProperty(PropertyUtils.java:148)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.getProperty(Constructor.java:287)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:208)
    ... 10 more

为什么抱怨无法找到属性AuthenticationConfig而AuthenticationConfig只是实例变量的名称？

Why it complains about cannot finding property AuthenticationConfig while AuthenticationConfig is just the name of the instance variable?

更新
我将实例变量从私有更改为公共后，它们被SnakeYaml识别，但是这个不是我们所期望的。这些类不被识别为JavaBean。

UPDATE After I changed the instance variables from "private" to "public", they were recognized by SnakeYaml, but this is not what we expect for sure. The classes are not recognized as JavaBean.

UPDATE
我找到了根本原因。这是命名惯例。如果你想让SnakeYaml解析你的yaml文件，必须遵守camelCase。 setter和getter方法的名称也很重要。假设有一个名为ldapConfig的私有实例变量，那么它的getter和setter的名称必须是getLdapConfig和setLdapConfig，即使getLDAPConfig和setLDAPConfig也不起作用。

UPDATE I found the root cause. It is the naming convention. If you want SnakeYaml to parse your yaml file, camelCase has to be complied with. The name of setter and getter method is also important. Say there is a private instance variable called ldapConfig, then its getter and setter's name has to be getLdapConfig and setLdapConfig, even getLDAPConfig and setLDAPConfig won't work.

推荐答案

错误的主要原因是您需要定义POJO类中Yaml文件中存在的所有属性（即 YamlConfiguraiton ）。

The main reason for the error is that you need to define all the attributes present in Yaml file in POJO class (i.e. YamlConfiguraiton).

您可以使用以下代码跳过未定义的属性。

You can use the below code to skip the undefined properties.

Representer representer = new Representer();
            representer.getPropertyUtils().setSkipMissingProperties(true);
            Yaml yaml = new Yaml(new Constructor(YamlConfiguraiton.class), representer);

首先，在Yaml文件中将属性名称重命名为camelCase。

Firstly, rename the attribute names to camelCase in Yaml file.

请参阅以下代码： -

Refer the below code:-

代码： -

public class YamlReadCustom {

    private static String yamlPath = "/authentication.yaml";

    public static void main(String[] args) {
        Representer representer = new Representer();
        representer.getPropertyUtils().setSkipMissingProperties(true);
        Yaml yaml = new Yaml(new Constructor(Authentication.class), representer);
        try(InputStream in = YamlReadCustom.class.getResourceAsStream (yamlPath)) {
            Authentication authentication = yaml.loadAs(in, Authentication.class);
            System.out.println(authentication.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

身份验证： -

public class Authentication {
    private String authenticationConfig;
    private String authencticationType;
    private LdapConfig ldapConfig;

    //getters and setters
}

LdapConfig： -

public class LdapConfig {
    private String ldapUrl;
    private String connectionType;
    private Map<String, Object> ldapSecurityConfig;
    //getters and setters
}

authentication.yaml

authenticationConfig:
authencticationType: LDAP
ldapConfig:
  ldapUrl: ldap://localhost:389
  connectionType: simple
  ldapSecurityConfig:
    rootDn: cn=manager,dc=maxcrc,dc=com
    rootPassword: secret
    userSearchDn: ou=People,dc=maxcrc,dc=com
    groupdSearchDb: ou=Groups,dc=maxcrc,dc=com

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