Package org.apache.flink.api.common.functions

Class WrappingFunction<T extends org.apache.flink.api.common.functions.Function>

  • Type Parameters:
    T -
    All Implemented Interfaces:
    Serializable, org.apache.flink.api.common.functions.Function, RichFunction
    @Internal
public abstract class WrappingFunction<T extends org.apache.flink.api.common.functions.Function>
extends AbstractRichFunction
    Wrapper around Function.
    See Also:
    Serialized Form

    • Field Detail

      • wrappedFunction

        protected T extends org.apache.flink.api.common.functions.Function wrappedFunction

    • Constructor Detail

      • WrappingFunction

        protected WrappingFunction​(T wrappedFunction)

    • Method Detail

      • open

        public void open​(OpenContext openContext)
          throws Exception
        Description copied from interface: RichFunction
        Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

        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);
     }
 }
        Specified by:
        open in interface RichFunction
        Overrides:
        open in class AbstractRichFunction
        Parameters:
        openContext - The context containing information about the context in which the function is opened.
        Throws:
        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.

      • close

        public void close()
           throws Exception
        Description copied from interface: RichFunction
        Tear-down method for the user code. It is called after the last call to the main working methods (e.g. map or join). For functions that are part of an iteration, this method will be invoked after each iteration superstep.

        This method can be used for clean up work.

        Specified by:
        close in interface RichFunction
        Overrides:
        close in class AbstractRichFunction
        Throws:
        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.

      • getWrappedFunction

        public T getWrappedFunction()