provided.rmiUtils.classServer

Class ClassServer

java.lang.Object

provided.rmiUtils.classServer.ClassServer

All Implemented Interfaces:

java.lang.Runnable

Direct Known Subclasses:

ClassFileServer

public abstract class ClassServer
extends java.lang.Object
implements java.lang.Runnable

ClassServer is an abstract class that provides the basic functionality of a mini-webserver, specialized to load class files only. A ClassServer must be extended and the concrete subclass should define the getBytes method which is responsible for retrieving the bytecodes for a class.

The ClassServer creates a thread that listens on a socket and accepts HTTP GET requests. The HTTP response contains the bytecodes for the class that requested in the GET header.

For loading remote classes, an RMI application can use a concrete subclass of this server in place of an HTTP server.

See Also:

ClassFileServer

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.function.Consumer<java.lang.String>	errMsgStrategy Strategy to display an error message.
private java.util.function.Consumer<java.lang.String>	infoMsgStrategy Strategy to display an informational message.
private boolean	isStop Flag to used to stop the server
private java.net.ServerSocket	server The socket object the server uses

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ClassServer(int port) Constructs a ClassServer that listens on port and obtains a class's bytecodes using the method getBytes.
protected	ClassServer(int port, java.util.function.Consumer<java.lang.String> infoMsgStrategy, java.util.function.Consumer<java.lang.String> errMsgStrategy) Constructs a ClassServer that listens on port and obtains a class's bytecodes using the method getBytes.

Method Summary

Modifier and Type	Method and Description
abstract byte[]	getBytes(java.lang.String path) Returns an array of bytes containing the bytecodes for the class represented by the argument path.
private static java.lang.String	getPath(java.io.BufferedReader in) Returns the path to the class file obtained from parsing the HTML header.
private void	newListener() Create a new thread to listen.
void	run() The "listen" thread that accepts a connection to the server, parses the header to obtain the class file name and sends back the bytecodes for the class (or error if the class is not found or the response was malformed).
protected void	showErrorMsg(java.lang.String msg) Encapsulated behavior to show an error message
protected void	showInfoMsg(java.lang.String msg) Encapsulated behavior to show an informational message
void	stop() Stops the server

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

server

private java.net.ServerSocket server

The socket object the server uses

isStop

private volatile boolean isStop

Flag to used to stop the server

infoMsgStrategy

private java.util.function.Consumer<java.lang.String> infoMsgStrategy

Strategy to display an informational message. Defaults to System.out.println()

errMsgStrategy

private java.util.function.Consumer<java.lang.String> errMsgStrategy

Strategy to display an error message. Defaults to System.err.println()

Constructor Detail

ClassServer

protected ClassServer(int port)
               throws java.io.IOException

Constructs a ClassServer that listens on port and obtains a class's bytecodes using the method getBytes. This constructor uses the default System.out.println() and System.err.println() methods to display info and error messages respectively.

Parameters:

port - the port number

Throws:

java.io.IOException - if the ClassServer could not listen on port.

ClassServer

protected ClassServer(int port,
                      java.util.function.Consumer<java.lang.String> infoMsgStrategy,
                      java.util.function.Consumer<java.lang.String> errMsgStrategy)
               throws java.io.IOException

Constructs a ClassServer that listens on port and obtains a class's bytecodes using the method getBytes. This constructor explicitly defines the strategies to use for displaying info and error messages.

Parameters:

port - the port number

infoMsgStrategy - Strategy to display an info message. Recommended: For increased system robustness, this strategy should first write to System.out.println()

errMsgStrategy - Strategy to display an error message. Recommended: For increased system robustness, this strategy should first write to System.err.println()

Throws:

java.io.IOException - if the ClassServer could not listen on port.

Method Detail

getBytes

public abstract byte[] getBytes(java.lang.String path)
                         throws java.io.IOException,
                                java.lang.ClassNotFoundException

Returns an array of bytes containing the bytecodes for the class represented by the argument path. The path is a dot separated class name with the ".class" extension removed.

Parameters:

path - fully qualified classname of the desired class

Returns:

the bytecodes for the class

Throws:

java.lang.ClassNotFoundException - if the class corresponding to path could not be loaded.

java.io.IOException - if error occurs reading the class

stop

public void stop()

Stops the server

run

public void run()

The "listen" thread that accepts a connection to the server, parses the header to obtain the class file name and sends back the bytecodes for the class (or error if the class is not found or the response was malformed).

Specified by:

run in interface java.lang.Runnable

newListener

private void newListener()

Create a new thread to listen.

getPath

private static java.lang.String getPath(java.io.BufferedReader in)
                                 throws java.io.IOException

Returns the path to the class file obtained from parsing the HTML header.

Parameters:

in - stream from which the header is read.

Returns:

the path to the desired file

Throws:

java.io.IOException - if the stream cannot be correctly read

showInfoMsg

protected void showInfoMsg(java.lang.String msg)

Encapsulated behavior to show an informational message

Parameters:

msg - Message to show.

showErrorMsg

protected void showErrorMsg(java.lang.String msg)

Encapsulated behavior to show an error message

Parameters:

msg - Message to show.