Package javassist.tools.rmi

Class ObjectImporter

  • All Implemented Interfaces:
    java.io.Serializable
    public class ObjectImporter
extends java.lang.Object
implements java.io.Serializable
    The object importer enables applets to call a method on a remote object running on the Webserver (the main class of this package).

    To access the remote object, the applet first calls lookupObject() and obtains a proxy object, which is a reference to that object. The class name of the proxy object is identical to that of the remote object. The proxy object provides the same set of methods as the remote object. If one of the methods is invoked on the proxy object, the invocation is delegated to the remote object. From the viewpoint of the applet, therefore, the two objects are identical. The applet can access the object on the server with the regular Java syntax without concern about the actual location.

    The methods remotely called by the applet must be public. This is true even if the applet's class and the remote object's classs belong to the same package.

    If class X is a class of remote objects, a subclass of X must be also a class of remote objects. On the other hand, this restriction is not applied to the superclass of X. The class X does not have to contain a constructor taking no arguments.

    The parameters to a remote method is passed in the call-by-value manner. Thus all the parameter classes must implement java.io.Serializable. However, if the parameter is the proxy object, the reference to the remote object instead of a copy of the object is passed to the method.

    Because of the limitations of the current implementation,

    • The parameter objects cannot contain the proxy object as a field value.
    • If class C is of the remote object, then the applet cannot instantiate C locally or remotely.

    All the exceptions thrown by the remote object are converted into RemoteException. Since this exception is a subclass of RuntimeException, the caller method does not need to catch the exception. However, good programs should catch the RuntimeException.

    See Also:
    AppletServer, RemoteException, Viewer, Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      ObjectImporter​(java.applet.Applet applet)
      Constructs an object importer.
      ObjectImporter​(java.lang.String servername, int port)
      Constructs an object importer.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.Object call​(int objectid, int methodid, java.lang.Object[] args)
      Calls a method on a remote object.
      java.lang.Object getObject​(java.lang.String name)
      Finds the object exported by a server with the specified name.
      java.lang.Object lookupObject​(java.lang.String name)
      Finds the object exported by the server with the specified name.
      void setHttpProxy​(java.lang.String host, int port)
      Sets an http proxy server.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • ObjectImporter

        public ObjectImporter​(java.applet.Applet applet)
        Constructs an object importer.

        Remote objects are imported from the web server that the given applet has been loaded from.

        Parameters:
        applet - the applet loaded from the Webserver.

      • ObjectImporter

        public ObjectImporter​(java.lang.String servername,
                      int port)
        Constructs an object importer.

        If you run a program with javassist.tools.web.Viewer, you can construct an object importer as follows: 

         Viewer v = (Viewer)this.getClass().getClassLoader();
 ObjectImporter oi = new ObjectImporter(v.getServer(), v.getPort());
        See Also:
        Viewer

    • Method Detail

      • getObject

        public java.lang.Object getObject​(java.lang.String name)
        Finds the object exported by a server with the specified name. If the object is not found, this method returns null.
        Parameters:
        name - the name of the exported object.
        Returns:
        the proxy object or null.

      • setHttpProxy

        public void setHttpProxy​(java.lang.String host,
                         int port)
        Sets an http proxy server. After this method is called, the object importer connects a server through the http proxy server.

      • lookupObject

        public java.lang.Object lookupObject​(java.lang.String name)
                              throws ObjectNotFoundException
        Finds the object exported by the server with the specified name. It sends a POST request to the server (via an http proxy server if needed).
        Parameters:
        name - the name of the exported object.
        Returns:
        the proxy object.
        Throws:
        ObjectNotFoundException

      • call

        public java.lang.Object call​(int objectid,
                             int methodid,
                             java.lang.Object[] args)
                      throws RemoteException
        Calls a method on a remote object. It sends a POST request to the server (via an http proxy server if needed).

        This method is called by only proxy objects.

        Throws:
        RemoteException