public static class StatefulStreamingJob.MyStatefulFunction extends RichMapFunction<Integer,String>
RichMapFunction
that keeps the required types of state. That is:
Constructor and Description |
---|
MyStatefulFunction() |
Modifier and Type | Method and Description |
---|---|
String |
map(Integer value)
The mapping method.
|
void |
open(OpenContext openContext)
Initialization method for the function.
|
close, getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContext
public void open(OpenContext openContext) throws Exception
RichFunction
The openContext object passed to the function can be used for configuration and initialization. The openContext contains some necessary information that were configured on the function in the program composition.
public class MyFilter extends RichFilterFunction<String> {
private String searchString;
public void open(OpenContext openContext) {
// initialize the value of searchString
}
public boolean filter(String value) {
return value.equals(searchString);
}
}
By default, this method does nothing.
1. If you implement open(OpenContext openContext)
, the open(OpenContext
openContext)
will be invoked and the open(Configuration parameters)
won't be
invoked. 2. If you don't implement open(OpenContext openContext)
, the open(Configuration parameters)
will be invoked in the default implementation of the open(OpenContext openContext)
.
openContext
- The context containing information about the context in which the function
is opened.Exception
- Implementations may forward exceptions, which are caught by the runtime.
When the runtime catches an exception, it aborts the task and lets the fail-over logic
decide whether to retry the task execution.public String map(Integer value) throws Exception
MapFunction
map
in interface MapFunction<Integer,String>
map
in class RichMapFunction<Integer,String>
value
- The input value.Exception
- This method may throw exceptions. Throwing an exception will cause the
operation to fail and may trigger recovery.Copyright © 2014–2024 The Apache Software Foundation. All rights reserved.