py4j.commands

Interface Command

All Known Implementing Classes:

AbstractCommand, ArrayCommand, CallCommand, ConstructorCommand, DirCommand, ExceptionCommand, FieldCommand, HelpPageCommand, JVMViewCommand, ListCommand, MemoryCommand, ReflectionCommand, ShutdownGatewayServerCommand, StreamCommand

public interface Command

This interface must be implemented by all commands.

Typically, each command will define a public constant field that contains the command name, i.e., a String that uniquely identifies the command.

The command name can be a String of any length, but it must not contain an end of line character and it cannot be the End of Command character, Protocol.END.

There is a command instance per GatewayConnection: this ensures that each command instance is accessed by only one thread/connection at a time.

Author:

barthelemy

Method Summary

Modifier and Type	Method and Description
void	execute(String commandName, BufferedReader reader, BufferedWriter writer)
String	getCommandName()
void	init(Gateway gateway, Py4JServerConnection connection) Called when a command instance is created and assigned to a connection.

Method Detail

execute

void execute(String commandName,
             BufferedReader reader,
             BufferedWriter writer)
      throws Py4JException,
             IOException

Parameters:

commandName - The command name that was extracted of the command.

reader - The reader from which to read the command parts. Each command part are expected to be on a separate line and readable through BufferedReader.readLine().

writer - The writer to which the return value should be written.

Throws:

Py4JException - If an error occurs while executing the command. All exceptions except IOException caused by the reader and the writer should be wrapper in a Py4JException instance.

IOException - If an error occurs while using the reader or the writer.

getCommandName

String getCommandName()

init

void init(Gateway gateway,
          Py4JServerConnection connection)

Called when a command instance is created and assigned to a connection.

Parameters:

gateway -

connection - the Py4JServerConnection this socket is assigned to