Keycloak自定义事件监听器启动报错：无法加载User_expleo类

问题描述 #

使用Keycloak 23.0.7 + JDK17，在Spring Boot项目中开发自定义事件监听器，执行mvn clean install后将jar包放入Keycloak的providers目录，启动Keycloak时报错无法找到com.expleo.msauth.entity.User_expleo类。

错误日志 #

Updating the configuration and installing your custom providers, if any. Please wait.
2024-03-12 09:39:04,854 WARN [io.quarkus.deployment.steps.ClassTransformingBuildStep] (build-18) Cannot transform com.expleo.msauth.entity.User_expleo as its containing application archive could not be found.
2024-03-12 09:39:11,757 INFO [io.quarkus.deployment.QuarkusAugmentor] (main) Quarkus augmentation completed in 16764ms
ERROR: Unexpected error when starting the server in (development) mode
ERROR: Failed to start quarkus
ERROR: Unable to load class [com.expleo.msauth.entity.User_expleo]
ERROR: com.expleo.msauth.entity.User_expleo
For more details run the same command passing the '--verbose' option. Also you can use '--help' to see the details about the usage of the particular command.

相关代码 #

自定义事件监听器（CustomEventListener.java）

package com.expleo.msauth.event;

import org.keycloak.events.Event;
import org.keycloak.events.EventListenerProvider;
import org.keycloak.events.EventType;
import org.keycloak.events.admin.AdminEvent;
import org.keycloak.models.KeycloakSession;
import org.keycloak.models.RealmProvider;

public class CustomEventListener implements EventListenerProvider {
    private KeycloakSession session;

    public CustomEventListener(KeycloakSession session) {
        this.session = session;
    }

    @Override
    public void onEvent(Event event) {
        System.out.println("Hi this event listner when user had registration + "+event.getType().name());

    }

    @Override
    public void onEvent(AdminEvent adminEvent, boolean b) {
        System.out.println("Hi this event listner for admin when user had registration + "+adminEvent.getId());
    }

    @Override
    public void close() {

    }
}

自定义事件监听器工厂类（CustomEventListenerProviderFactory.java）

package com.expleo.msauth.event;

import org.keycloak.Config;
import org.keycloak.events.EventListenerProvider;
import org.keycloak.events.EventListenerProviderFactory;
import org.keycloak.models.KeycloakSession;
import org.keycloak.models.KeycloakSessionFactory;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.EventListenerFactory;

import java.lang.reflect.Method;

public class CustomEventListenerProviderFactory implements EventListenerProviderFactory {

    @Override
    public EventListenerProvider create(KeycloakSession keycloakSession) {
        return new CustomEventListener(keycloakSession);
    }

    @Override
    public void init(Config.Scope scope) {

    }

    @Override
    public void postInit(KeycloakSessionFactory keycloakSessionFactory) {

    }

    @Override
    public void close() {

    }

    @Override
    public String getId() {
        return "CustomEventListener";
    }
}

User_expleo实体类（User_expleo.java）

package com.expleo.msauth.entity;

import com.expleo.msauth.enums.Status;
import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data @Builder
@NoArgsConstructor
@AllArgsConstructor
@Entity
public class User_expleo {
    @Id
    private String id;
    private String firstName;
    private String lastName;
    private String userName;
    private String email;
    private String password;

    @Enumerated(EnumType.STRING)
    @Column(columnDefinition = "varchar(255) default 'OFFLINE'")
    private Status status;
}

解决方案 #

1. 检查jar包是否包含缺失类 #

解压生成的jar包，确认com/expleo/msauth/entity/User_expleo.class文件是否存在：

• 若不存在，检查Maven配置，确保该类所在模块未被打包插件排除；多模块项目需确认监听器模块已正确依赖包含该实体类的模块。

2. 移除Spring相关依赖与代码 #

Keycloak基于Quarkus运行，不兼容Spring上下文，需清理工厂类中的Spring相关内容：

• 删除以下导入语句：

  import org.springframework.context.ApplicationListener;
  import org.springframework.context.event.EventListenerFactory;
  

• 移除未使用的java.lang.reflect.Method导入。

3. 按Keycloak扩展规范打包 #

普通Spring Boot jar无法直接作为Keycloak扩展使用，需调整打包配置：

• 在pom.xml中添加Keycloak扩展打包插件：

  <build>
    <plugins>
      <plugin>
        <groupId>org.keycloak</groupId>
        <artifactId>keycloak-maven-plugin</artifactId>
        <version>23.0.7</version>
        <executions>
          <execution>
            <id>build</id>
            <goals>
              <goal>build</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  

• 执行mvn clean install后，将target目录下生成的扩展jar（通常带-keycloak-extension后缀）放入Keycloak的providers目录。

4. 重新构建Keycloak配置 #

放入扩展jar后，执行构建命令让Keycloak识别扩展：

# Linux/macOS
./kc.sh build

# Windows
kc.bat build

完成后再启动Keycloak。

5. 确保实体类依赖被打包 #

User_expleo使用了JPA和Lombok，需确保这些依赖被包含进jar：

• 在pom.xml中设置相关依赖的scope为compile，避免设为provided或test；
• 若需，使用maven-shade-plugin将所有依赖打包成一个jar，防止依赖缺失。

内容的提问来源于stack exchange，提问作者youssef elmesbahi