我是新来Kafka的。我想执行以下kstream globalktable纯dsl左连接操作,而不是使用map操作。
我有一个输入流 a.topic
即<string,a>,其中值:
{
"b_obj": {
"b_value": "xyz",
"c_list": [
{
"d_obj": {
"d_id1": "value1",
"d_id2": "value2",
"d_value": "some value"
},
"c_value": "jkl"
},
{
"d_obj": {
"d_id1": "value3",
"d_id2": "value4",
"d_value": "some value 2"
},
"c_value": "pqr"
}
]
},
"a_value": "abcd"
}
另一个输入主题 e.topic
即<string,e>,其中值:
{
"e_id1": "value1",
"e_id2": "value2",
"e_value": "some value"
}
我要执行左连接操作 a.topic
是一个流和主数据 e.topic
是实现结果值的全局表
{
"b_obj": {
"b_value": "xyz",
"c_list": [
{
"d_obj": {
"d_id1": "value1",
"d_id2": "value2",
"d_value": "some value"
},
"e_obj": {
"e_id1": "value1",
"e_id2": "value2",
"e_value": "some value a"
},
"c_value": "jkl"
},
{
"d_obj": {
"d_id1": "value3",
"d_id2": "value4",
"d_value": "some value 2"
},
"e_obj": {
"e_id1": "value3",
"e_id2": "value4",
"e_value": "some value b"
},
"c_value": "pqr"
}
]
},
"a_value": "abcd"
}
连接条件是 a.b.c[i].d.d_id1 == e.e_id1 && a.b.c[i].d.d_id2 == e.e_id2
代码:
public class ComplexBeanStream {
public static void main(String[] args) {
Serde<A> aSerde = new JsonSerde<>(A.class);
Serde<E> eSerde = new JsonSerde<>(E.class);
final Properties streamsConfiguration = new Properties();
streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "complex-bean-app");
streamsConfiguration.put(StreamsConfig.CLIENT_ID_CONFIG, "complex-bean-client");
streamsConfiguration.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
StreamsBuilder builder = new StreamsBuilder();
final GlobalKTable<String, E> eGlobalTable =
builder.globalTable(
"e.topic",
Materialized.<String, E, KeyValueStore<Bytes, byte[]>>
as("E-STORE")
.withKeySerde(Serdes.String())
.withValueSerde(eSerde)
);
final KStream<String, A> aStream =
builder.stream(
"a.topic",
Consumed.with(Serdes.String(), aSerde));
// perform left-join here
Topology topology = builder.build();
System.out.println("\n\nComplexBeanStream Topology: \n" + topology.describe());
final KafkaStreams streams = new KafkaStreams(topology, streamsConfiguration);
streams.cleanUp();
streams.start();
Runtime.getRuntime().addShutdownHook(new Thread(streams::close));
}
}
class A {
private B b_obj;
private String a_value;
}
class B {
private List<C> c_list;
private String b_value;
}
class C {
private D d_obj;
private E e_obj;
private String c_value;
}
class D {
private String d_id1;
private String d_id2;
private String d_value;
}
class E {
private String e_id1;
private String e_id2;
private String e_value;
}
1条答案
按热度按时间g6ll5ycj1#
在您的案例中,只要连接查找基于值而不是键,就不可能在没有Map的情况下进行连接。
kafka流只能基于两侧的同一个密钥进行连接。这意味着您应该Map并为连接的两侧选择新的键(重新设置键),以便实现
a.b.c[i].d.d_id1 == e.e_id1 && a.b.c[i].d.d_id2 == e.e_id2
.在这种情况下,一方可能
[a.b.c[i].d.d_id1, a.b.c[i].d.d_id2]
作为它的钥匙和另一面[e.e_id1, e.e_id2]
. 如果有匹配项,则可以将这些值连接到新对象。也许你应该把你的c_list
在重新设置关键帧之前。阅读Kafka流的连接也是很有帮助的。