如何使用 Spring Boot Java Config 编写自定义 Apache Camel 组件/端点答案

【问题标题】：How to write a custom Apache Camel component/endpoint with Spring Boot Java Config如何使用 Spring Boot Java Config 编写自定义 Apache Camel 组件/端点
【发布时间】：2020-02-03 12:31:25
【问题描述】：

我正在寻找有关如何在 Java Config 中使用 Spring Boot 实现自定义 Apache Camel component 和 endpoint 的示例/文档。我不知道我必须如何注释类，请你提供一个例子。如果不使用 Spring，我的（工作）代码如下所示：

public class MyCustomComponent extends DefaultComponent {
    @Override
    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
        Endpoint endpoint = new MyCustomEndpoint(uri, this);
        setProperties(endpoint, parameters);
        return endpoint;
    }
}

Registered 是resources/META-INF/services/org/apache/camel/component/myscheme 中具有MyCustomComponent 类的FQN 的组件。

public class MyCustomEndpoint extends DefaultEndpoint {

    public MyCustomEndpoint(String uri, MyCustomComponent component) {
        super(uri, component);
    }

    @Override
    public Producer createProducer() throws Exception {
        return new MyCustomProducer(this);
    }

    @Override
    public Consumer createConsumer(Processor processor) throws Exception {
        throw new UnsupportedOperationException("Not implemented yet: MyCustomEndpoint#createConsumer");
    }

    @Override
    public boolean isSingleton() {
        return false;
    }
}

public class MyCustomProducer extends DefaultProducer {

    public MyCustomProducer(Endpoint endpoint) {
        super(endpoint);
    }

    @Override
    public void process(Exchange exchange) throws Exception {
    }
}

【问题讨论】：

以现有的Camel组件为例，isSingleton也应该返回true。
@Claus Ibsen 感谢您的回答。如何将 Spring Bean 注入 MyCustomProducer

标签： spring apache-camel spring-camel

【解决方案1】：

经过大量搜索，我找到了基于 Spring 的BeanFactory 的解决方案。主要障碍是循环依赖（组件 -> 端点 -> 组件 | 端点 -> 生产者 -> 端点）。一开始我介绍了一个SpringConfiguration类：

@Configuration
public class ComponentConfiguration {

    @Bean("myCustomEndpoint")
    @Scope("prototype")
    public MyCustomEndpoint myCustomEndpoint(String uri, MyCustomComponent component) {
        MyCustomEndpoint endpoint = new MyCustomEndpoint(uri, component);
        return endpoint;
    }

    @Bean("myCustomProducer")
    @Scope("prototype")
    public MyCustomProducer myCustomProducer(MyCustomEndpoint endpoint) {
        return new MyCustomProducer(endpoint);
    }
}

使用@Componentannotation 使自定义 Camel 组件成为 Spring 组件，因此我可以注入 BeanFactory 以按需创建 MyCustomEndpoint 类的实例（prototype 范围）。

@org.springframework.stereotype.Component
public class MyCustomComponent extends DefaultComponent {

    @Autowired
    private BeanFactory beanFactory;

    @Override
    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
        MyCustomEndpoint endpoint = (MyCustomEndpoint) beanFactory.getBean("myCustomEndpoint", uri, this);
        setProperties(endpoint, parameters);
        return endpoint;
    }
}

public class MyCustomEndpoint extends DefaultEndpoint {

    @Autowired
    private BeanFactory beanFactory;

    public MyCustomEndpoint(String uri, MyCustomComponent component) {
        super(uri, component);
    }

    @Override
    public Producer createProducer() throws Exception {
        MyCustomProducer producer = (MyCustomProducer) beanFactory.getBean("myCustomProducer",  this);
        return producer;
    }

    @Override
    public Consumer createConsumer(Processor processor) throws Exception {
        throw new UnsupportedOperationException("Not implemented yet: MyCustomEndpoint#createConsumer");
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

public class MyCustomProducer extends DefaultProducer {

    // Now, I am able to inject some other Spring beans
    @Autowired
    private AnotherSpringBean bean;

    public MyCustomProducer(Endpoint endpoint) {
        super(endpoint);
    }

    @Override
    public void process(Exchange exchange) throws Exception {
    }
}

请注意，Camel 组件MyCustomComponent 已经在resources/META-INF/services/org/apache/camel/component/myscheme 中注册：

class=<fqn-of-MyCustomComponent>

【讨论】：