如何避免在 pojo 中依赖骆驼？：骆驼示例-spring-boot-rest-jpa：答案

【问题标题】：How can I avoid putting camel dependency in pojo? : camel-example-spring-boot-rest-jpa :如何避免在 pojo 中依赖骆驼？：骆驼示例-spring-boot-rest-jpa：
【发布时间】：2017-10-31 01:27:29
【问题描述】：

camel-example-spring-boot-rest-jpa

我正在查看 Order.java ：

@Consumed
public void setProcessed() {
}

我了解这是必需的，因此 Camel 不需要重新处理已处理的订单。但是，如果不向 Order.java pojo 添加骆驼依赖项，如何实现呢？

原因：在现实生活中我们需要在不给pojo添加外部依赖的情况下实现相同的功能。

参考：https://github.com/apache/camel/blob/master/examples/camel-example-spring-boot-rest-jpa/src/main/java/org/apache/camel/example/spring/boot/rest/jpa/Order.java

编辑 1：按照claus的建议，创建了一个自定义删除处理器

public class OrderProcessedHandler implements DeleteHandler<Order>{
    @Override
    public void deleteObject(EntityManager arg0, Object arg1, Exchange arg2) {
        ((Order) arg1).setProcessed(true);
    }
}

并在端点uri中指定：

    // A second route polls the DB for new orders and processes them


from("jpa:sb.app.bo.Order" 
+ "?consumer.namedQuery=new-orders"
+ "&consumer.delay={{example.processOrderPeriod:25s}}"
+ "&consumeDelete=false"
+ "&deleteHandler=sb.app.camel.routes.OrderProcessedHandler")
.routeId("process-order")
.log("Processed order #id ${body.id} with ${body.amount} ");

无法使用Handler，错误日志：

2017-10-31 15:45:33.688 ERROR 1429 --- [  restartedMain] o.s.boot.SpringApplication               : Application startup failed

org.apache.camel.RuntimeCamelException: org.apache.camel.FailedToCreateRouteException: Failed to create route process-order: Route(process-order)[[From[jpa:sb.app.bo.Order?consumer.name... because of Failed to resolve endpoint: jpa://sb.app.bo.Order?consumeDelete=false&consumer.delay=25s&consumer.namedQuery=new-orders&deleteHandler=sb.app.camel.routes.OrderProcessedHandler due to: Could not find a suitable setter for property: deleteHandler as there isn't a setter method with same type: java.lang.String nor type conversion possible: No type converter available to convert from type: java.lang.String to the required type: org.apache.camel.component.jpa.DeleteHandler with value sb.app.camel.routes.OrderProcessedHandler
    at org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException(ObjectHelper.java:1831) ~[camel-core-2.20.0.jar:2.20.0]
    at org.apache.camel.spring.SpringCamelContext.start(SpringCamelContext.java:136) ~[camel-spring-2.20.0.jar:2.20.0]
    at org.apache.camel.spring.SpringCamelContext.onApplicationEvent(SpringCamelContext.java:174) ~[camel-spring-2.20.0.jar:2.20.0]

解决方案（基于@claus 建议）：

// A second route polls the DB for new orders and processes them
from("jpa:sb.app.bo.Order"  //select * from orders where consumed = false
    + "?consumer.namedQuery=query_new_orders"
    + "&consumer.delay={{example.processOrderPeriod:5s}}"
    + "&consumeDelete=false"
    + "&deleteHandler=#orderProcessedMarker")
    .routeId("process-order")
    .log("Processed order #id ${body.id} with ${body.amount} copies of the «${body.book.description}» book");

DeleteHandler bean：

@Bean(name = "orderProcessedMarker")
public DeleteHandler<Order> createOrderProcessHandler() {
    return new DeleteHandler<Order>() {
        @Override
        public void deleteObject(EntityManager arg0, Object arg1, Exchange arg2) {
            ((Order) arg1).setProcessed(true);
        }
    };
}

【问题讨论】：

您的意思是要排除某些特定的依赖项吗？

标签： apache-camel

【解决方案1】：

您可以使用自定义的deleteHandler，而不是使用@Consumed，您可以在JPA 端点上配置它。

【讨论】：

添加了 OrderDeleteHandler 并更新了 uri（见编辑），但是 deleteHandler 没有连接。 URI 格式问题？
在端点 uri 中使用 '#beanName`，并使 Spring Boot 通过 @Component("beanName") 使用您为 beanName 选择的名称将类公开为 bean。