1 package org.apache.turbine.services.assemblerbroker.util.python;
2
3
4 /*
5 * Licensed to the Apache Software Foundation (ASF) under one
6 * or more contributor license agreements. See the NOTICE file
7 * distributed with this work for additional information
8 * regarding copyright ownership. The ASF licenses this file
9 * to you under the Apache License, Version 2.0 (the
10 * "License"); you may not use this file except in compliance
11 * with the License. You may obtain a copy of the License at
12 *
13 * http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing,
16 * software distributed under the License is distributed on an
17 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
18 * KIND, either express or implied. See the License for the
19 * specific language governing permissions and limitations
20 * under the License.
21 */
22
23
24 import java.io.File;
25
26 import org.apache.commons.configuration.Configuration;
27 import org.apache.commons.lang.StringUtils;
28 import org.apache.commons.logging.Log;
29 import org.apache.commons.logging.LogFactory;
30 import org.apache.turbine.modules.Assembler;
31 import org.apache.turbine.modules.Loader;
32 import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker;
33 import org.apache.turbine.services.assemblerbroker.util.AssemblerFactory;
34 import org.python.core.Py;
35 import org.python.util.PythonInterpreter;
36
37 /**
38 * A factory that attempts to load a python class in the
39 * JPython interpreter and execute it as a Turbine screen.
40 * The JPython script should inherit from Turbine Screen or one
41 * of its subclasses.
42 *
43 * @author <a href="mailto:leon@opticode.co.za">Leon Messerschmidt</a>
44 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
45 * @version $Id: PythonBaseFactory.java 1078552 2011-03-06 19:58:46Z tv $
46 */
47 public abstract class PythonBaseFactory<T extends Assembler>
48 implements AssemblerFactory<T>
49 {
50 /** Key for the python path */
51 public static final String PYTHON_PATH = "python.path";
52
53 /** Global config file. This is executed before every screen */
54 public static final String PYTHON_CONFIG_FILE = "conf.py";
55
56 /** Logging */
57 private static Log log = LogFactory.getLog(PythonBaseFactory.class);
58
59 /** Our configuration */
60 private final Configuration conf =
61 TurbineAssemblerBroker.getService().getConfiguration();
62
63 /**
64 * Get an Assembler.
65 *
66 * @param subDirectory subdirectory within python.path
67 * @param name name of the requested Assembler
68 * @return an Assembler
69 * @throws Exception generic exception
70 */
71 public T getAssembler(String subDirectory, String name)
72 throws Exception
73 {
74 String path = conf.getString(PYTHON_PATH);
75
76 if (StringUtils.isEmpty(path))
77 {
78 throw new Exception(
79 "Python path not found - check your Properties");
80 }
81
82 log.debug("Screen name for JPython: " + name);
83
84 T assembler = null;
85
86 String confName = path + "/" + PYTHON_CONFIG_FILE;
87
88 // The filename of the Python script
89 StringBuffer fName = new StringBuffer();
90
91 fName.append(path);
92 fName.append("/");
93 fName.append(subDirectory);
94 fName.append("/");
95 fName.append(name.toLowerCase());
96 fName.append(".py");
97
98 File f = new File(fName.toString());
99
100 if (f.exists())
101 {
102 try
103 {
104 // We try to open the Py Interpreter
105 PythonInterpreter interp = new PythonInterpreter();
106
107 // Make sure the Py Interpreter use the right classloader
108 // This is necessary for servlet engines generally has
109 // their own classloader implementations and servlets aren't
110 // loaded in the system classloader. The python script will
111 // load java package
112 // org.apache.turbine.services.assemblerbroker.util.python;
113 // the new classes to it as well.
114 Py.getSystemState().setClassLoader(
115 this.getClass().getClassLoader());
116
117 // We import the Python SYS module. Now we don't need to do this
118 // explicitely in the script. We always use the sys module to
119 // do stuff like loading java package
120 // org.apache.turbine.services.assemblerbroker.util.python;
121 interp.exec("import sys");
122
123 // Now we try to load the script file
124 interp.execfile(confName);
125 interp.execfile(fName.toString());
126
127 try
128 {
129 // We create an instance of the screen class from the
130 // python script
131 interp.exec("scr = " + name + "()");
132 }
133 catch (Throwable e)
134 {
135 throw new Exception(
136 "\nCannot create an instance of the python class.\n"
137 + "You probably gave your class the wrong name.\n"
138 + "Your class should have the same name as your "
139 + "filename.\nFilenames should be all lowercase and "
140 + "classnames should start with a capital.\n"
141 + "Expected class name: " + name + "\n");
142 }
143
144 // Here we convert the python sceen instance to a java instance.
145 assembler = (T) interp.get("scr", Assembler.class);
146 }
147 catch (Exception e)
148 {
149 // We log the error here because this code is not widely tested
150 // yet. After we tested the code on a range of platforms this
151 // won't be useful anymore.
152 log.error("PYTHON SCRIPT SCREEN LOADER ERROR:", e);
153 throw e;
154 }
155 }
156 return assembler;
157 }
158
159 /**
160 * Get the loader for this type of assembler
161 *
162 * @return a Loader
163 */
164 public abstract Loader<T> getLoader();
165
166 /**
167 * Get the size of a possibly configured cache
168 *
169 * @return the size of the cache in bytes
170 */
171 public int getCacheSize()
172
173 {
174 return getLoader().getCacheSize();
175 }
176 }