我创建了一个KStream和一个KTable来读取来自不同主题的消息。然后，我尝试使用.join()函数（文档说这是内部连接）将它们加入另一个KStream。令我感到困惑的是，输出显示真正发生的是左联接。
下面，我将介绍KStream和KTable的实现及其输出。
KStream：
KStream<String, String> s_order = builder.stream("s-order-topic", Consumed.with(Serdes.String(),Serdes.String()))
.mapValues(value -> {
String time;
JSONObject json = new JSONObject(value);
if (json.getString("op_type").equals("I")) {
time = "after";
}else {
time = "before";
}
JSONObject json2 = new JSONObject(json.getJSONObject(time).toString());
return json2.toString();
})
.selectKey((key, value) -> {
JSONObject json = new JSONObject(value);
return String.valueOf(json.getLong("ID"));
});
输出：
23 {"CODE":"AAAA55","STATUS":"SUBMITTED","ID":23}
4 {"CODE":"AAAA18","STATUS":"CANCELED","ID":4}
2 {"CODE":"AAAA32","STATUS":"SUBMITTED","ID":2}
24 {"CODE":"AAAA11","STATUS":"NOT COMPLETED","ID":24}
16 {"CODE":"AAAA93","STATUS":"CANCELED","ID":16}
19 {"CODE":"AAAA65","STATUS":"SUBMITTED","ID":19}
25 {"CODE":"AAAA71","STATUS":"COMPLETED","ID":25}
3 {"CODE":"AAAA91","STATUS":"NOT COMPLETED","ID":3}
17 {"CODE":"AAAA31","STATUS":"SUBMITTED","ID":17}
1 {"CODE":"AAAA89","STATUS":"NOT COMPLETED","ID":1}
KTable：
KTable<String, String> s_item_table = builder.stream("s-order-item-topic", Consumed.with(Serdes.String(),Serdes.String()))
.mapValues(value -> {
String time;
JSONObject json = new JSONObject(value);
if (json.getString("op_type").equals("I")) {
time = "after";
}else {
time = "before";
}
JSONObject json2 = new JSONObject(json.getJSONObject(time).toString());
return json2.toString();
})
.groupBy((key, value) -> {
JSONObject json = new JSONObject(value);
return String.valueOf(json.getLong("ID"));
}, Grouped.with(Serdes.String(), Serdes.String()))
.reduce((prev,newval)->newval);
输出：
17 {"DESCRIPTION":"blah blah blah","QUANTITY":6,"ID_CUSTOMER_ORDER":"GR0100519","ID":17}
9 {"DESCRIPTION":"blah blah blah","QUANTITY":7,"ID_CUSTOMER_ORDER":"GR0100575","ID":9}
24 {"DESCRIPTION":"blah blah blah","QUANTITY":6,"ID_CUSTOMER_ORDER":"GR0100850","ID":24}
27 {"DESCRIPTION":"blah blah blah","QUANTITY":9,"ID_CUSTOMER_ORDER":"GR0100953","ID":27}
25 {"DESCRIPTION":"blah blah blah","QUANTITY":5,"ID_CUSTOMER_ORDER":"GR0100577","ID":25}
22 {"DESCRIPTION":"blah blah blah","QUANTITY":1,"ID_CUSTOMER_ORDER":"GR0100639","ID":22}
24 {"DESCRIPTION":"blah blah blah","QUANTITY":6,"ID_CUSTOMER_ORDER":"GR0100974","ID":24}
19 {"DESCRIPTION":"blah blah blah","QUANTITY":9,"ID_CUSTOMER_ORDER":"GR0100674","ID":19}
15 {"DESCRIPTION":"blah blah blah","QUANTITY":6,"ID_CUSTOMER_ORDER":"GR0100151","ID":15}
2 {"DESCRIPTION":"blah blah blah","QUANTITY":4,"ID_CUSTOMER_ORDER":"GR0100326","ID":2}
1 {"DESCRIPTION":"blah blah blah","QUANTITY":5,"ID_CUSTOMER_ORDER":"GR0100913","ID":1}
17 {"DESCRIPTION":"blah blah blah","QUANTITY":9,"ID_CUSTOMER_ORDER":"GR0100448","ID":17}
29 {"DESCRIPTION":"blah blah blah","QUANTITY":2,"ID_CUSTOMER_ORDER":"GR0100238","ID":29}
5 {"DESCRIPTION":"blah blah blah","QUANTITY":3,"ID_CUSTOMER_ORDER":"GR0100687","ID":5}
4 {"DESCRIPTION":"blah blah blah","QUANTITY":8,"ID_CUSTOMER_ORDER":"GR0100580","ID":4}
6 {"DESCRIPTION":"blah blah blah","QUANTITY":8,"ID_CUSTOMER_ORDER":"GR0100632","ID":6}
17 {"DESCRIPTION":"blah blah blah","QUANTITY":3,"ID_CUSTOMER_ORDER":"GR0100365","ID":17}
7 {"DESCRIPTION":"blah blah blah","QUANTITY":8,"ID_CUSTOMER_ORDER":"GR0100974","ID":7}
2 {"DESCRIPTION":"blah blah blah","QUANTITY":8,"ID_CUSTOMER_ORDER":"GR010084","ID":2}
已加入流：
KStream<String, String> s_joined = s_order
.join(s_item_table, (left,right) -> left + right)
.mapValues(value -> {
String[] arrOfstr = value.split("(?<=})");
JSONObject jl = new JSONObject(arrOfstr[0]);
JSONObject jr = new JSONObject(arrOfstr[1]);
JSONObject json = new JSONObject();
Iterator<String> keys = jl.keys();
while(keys.hasNext()) {
String key = keys.next();
json.put(key, jl.get(key));
}
keys = jr.keys();
while(keys.hasNext()) {
String key = keys.next();
json.put(key, jr.get(key));
}
return json.toString();
});
输出：
23 {"CODE":"AAAA82","STATUS":"SUBMITTED","ID":23}
7 {"CODE":"AAAA74","STATUS":"CANCELED","DESCRIPTION":"blah blah blah","QUANTITY":0,"ID_CUSTOMER_ORDER":"GR0100832","ID":7}
11 {"CODE":"AAAA55","STATUS":"PENDING","DESCRIPTION":"blah blah blah","QUANTITY":8,"ID_CUSTOMER_ORDER":"GR0100206","ID":11}
23 {"CODE":"AAAA82","STATUS":"SUBMITTED","ID":23}
4 {"CODE":"AAAA18","STATUS":"CANCELED","DESCRIPTION":"blah blah blah","QUANTITY":3,"ID_CUSTOMER_ORDER":"GR0100182","ID":4}
2 {"CODE":"AAAA32","STATUS":"SUBMITTED","DESCRIPTION":"blah blah blah","QUANTITY":4,"ID_CUSTOMER_ORDER":"GR0100326","ID":2}
24 {"CODE":"AAAA11","STATUS":"NOT COMPLETED","DESCRIPTION":"blah blah blah","QUANTITY":6,"ID_CUSTOMER_ORDER":"GR0100974","ID":24}
16 {"CODE":"AAAA87","STATUS":"SUBMITTED","ID":16}
19 {"CODE":"AAAA65","STATUS":"SUBMITTED","DESCRIPTION":"blah blah blah","QUANTITY":9,"ID_CUSTOMER_ORDER":"GR0100674","ID":19}
25 {"CODE":"AAAA71","STATUS":"COMPLETED","DESCRIPTION":"blah blah blah","QUANTITY":5,"ID_CUSTOMER_ORDER":"GR0100577","ID":25}
3 {"CODE":"AAAA80","STATUS":"SUBMITTED","ID":3}
17 {"CODE":"AAAA31","STATUS":"SUBMITTED","DESCRIPTION":"blah blah blah","QUANTITY":9,"ID_CUSTOMER_ORDER":"GR0100448","ID":17}
1 {"CODE":"AAAA89","STATUS":"NOT COMPLETED","DESCRIPTION":"blah blah blah","QUANTITY":5,"ID_CUSTOMER_ORDER":"GR0100913","ID":1}
您可以看到即使KTable没有任何价值，短消息也已发布，仅使用Stream中的消息。这不是内部联接。我想念什么吗？