01: package org.apache.velocity.app.event;
02:
03: /*
04: * Licensed to the Apache Software Foundation (ASF) under one
05: * or more contributor license agreements. See the NOTICE file
06: * distributed with this work for additional information
07: * regarding copyright ownership. The ASF licenses this file
08: * to you under the Apache License, Version 2.0 (the
09: * "License"); you may not use this file except in compliance
10: * with the License. You may obtain a copy of the License at
11: *
12: * http://www.apache.org/licenses/LICENSE-2.0
13: *
14: * Unless required by applicable law or agreed to in writing,
15: * software distributed under the License is distributed on an
16: * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17: * KIND, either express or implied. See the License for the
18: * specific language governing permissions and limitations
19: * under the License.
20: */
21:
22: /**
23: * Strategy object used to execute event handler method. Will be called
24: * while looping through all the chained event handler implementations.
25: * Each EventHandler method call should have a parallel executor object
26: * defined.
27: *
28: * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
29: * @version $Id: EventHandlerMethodExecutor.java 470256 2006-11-02 07:20:36Z wglass $
30: */
31: public interface EventHandlerMethodExecutor {
32: /**
33: * Execute the event handler method. If Object is not null, do not
34: * iterate further through the handler chain.
35: * If appropriate, the returned Object will be the return value.
36: *
37: * @param handler call the appropriate method on this handler
38: * @exception Exception generic exception potentially thrown by event handlers
39: */
40: public void execute(EventHandler handler) throws Exception;
41:
42: /**
43: * Called after execute() to see if iterating should stop. Should
44: * always return false before method execute() is run.
45: *
46: * @return true if no more event handlers for this method should be called.
47: */
48: public boolean isDone();
49:
50: /**
51: * Get return value at end of all the iterations
52: *
53: * @return null if no return value is required
54: */
55: public Object getReturnValue();
56: }
|