使用Camel-Kafka的ProducerTemplate sendBody（）方法时，无法为终结点创建生产者

Question

我正在测试使用Apache Camel在Kafka(0.8.2.1)上发送消息的simple producer。我在Camel中使用java DSL创建了endpoint。

CamelContext ctx =new DefaultCamelContext();
PropertiesComponent properties=new PropertiesComponent();

properties.setLocation("com/camel/test/props.properties");
ctx.addComponent("properties",properties);

final String uri= "kafka://{{kafka.host}}?topic={{topic}}&zookeeperHost={{zookeeperHost}}&zookeeperPort={{zookeeperPort}}";
String uriParams = "&metadata.broker.list={{metadata.broker.list}";

ctx.addRoutes(new RouteBuilder() {
    public void configure() { //
        from(uri+"&groupId={{groupId}}")
        .process(new Processor() {
            @Override
            public void process(Exchange exchange) throws Exception {
                System.out.println(exchange.getIn().getBody());
            }
        })
        ;
    }
});


ctx.start();

ProducerTemplate tmp = ctx.createProducerTemplate();
tmp.sendBody(ctx.getEndpoint(uri), "my test is working");// Error occurs here

现在我想使用Apache Camel提供的ProducerTempalte在kafka上发送消息。但我在运行该程序时得到以下错误注意：Zookeeper和Kafka已启动并可以使用Kafka控制台生成/消费消息。

Exception in thread "main" org.apache.camel.FailedToCreateProducerException: Failed to create Producer for endpoint: Endpoint[kafka://localhost:9092?topic=test&zookeeperHost=localhost&zookeeperPort=2181]. Reason: java.lang.NullPointerException
    at org.apache.camel.impl.ProducerCache.doGetProducer(ProducerCache.java:407)
    at org.apache.camel.impl.ProducerCache.doInProducer(ProducerCache.java:220)
    at org.apache.camel.impl.ProducerCache.sendExchange(ProducerCache.java:343)
    at org.apache.camel.impl.ProducerCache.send(ProducerCache.java:184)
    at org.apache.camel.impl.DefaultProducerTemplate.send(DefaultProducerTemplate.java:124)
    at org.apache.camel.impl.DefaultProducerTemplate.sendBody(DefaultProducerTemplate.java:137)
    at com.camel.test.CamelTest.main(CamelTest.java:45)
Caused by: java.lang.NullPointerException
    at java.util.Hashtable.put(Hashtable.java:514)
    at org.apache.camel.component.kafka.KafkaProducer.getProps(KafkaProducer.java:54)
    at org.apache.camel.component.kafka.KafkaProducer.doStart(KafkaProducer.java:61)
    at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
    at org.apache.camel.impl.DefaultCamelContext.startService(DefaultCamelContext.java:2869)
    at org.apache.camel.impl.DefaultCamelContext.doAddService(DefaultCamelContext.java:1097)
    at org.apache.camel.impl.DefaultCamelContext.addService(DefaultCamelContext.java:1058)
    at org.apache.camel.impl.ProducerCache.doGetProducer(ProducerCache.java:405)
    ... 6 more

我猜这些属性不是为生产者设置的，而是不知道如何在生产者模板中设置。

Answer 1

uri应该将broker列表作为服务器名（不要责怪我没有创建这个组件的语法）。

final String uri= "kafka://{{metadata.broker.list}}?topic={{topic}}&zookeeperHost={{zookeeperHost}}&zookeeperPort={{zookeeperPort}}";