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1
18 package org.apache.beehive.netui.script;
19
20 import java.util.HashMap  ;
21 import java.util.Map ;
22
23 import org.apache.beehive.netui.util.config.ConfigUtil;
24 import org.apache.beehive.netui.util.config.bean.NetuiConfigDocument.NetuiConfig;
25 import org.apache.beehive.netui.util.config.bean.ExpressionLanguages;
26 import org.apache.beehive.netui.util.config.bean.ExpressionLanguages.ExpressionLanguage;
27 import org.apache.beehive.netui.util.logging.Logger;
28
29
32 public class ExpressionEvaluatorFactory {
33
34 private static final Logger _logger = Logger.getInstance(ExpressionEvaluatorFactory.class);
35
36 private static final HashMap FACTORY_MAP = new HashMap ();
37 private static ExpressionEngineFactory DEFAULT_FACTORY;
38
39 static {
40 try {
41 DEFAULT_FACTORY = initialize(FACTORY_MAP);
42 } catch(Exception e) {
43 DEFAULT_FACTORY = null;
44
45 if(_logger.isErrorEnabled())
46 _logger.error("An exception occurred loading the expression evaluator configuration. Cause: " + e, e);
47 }
48 }
49
50
55 public final static ExpressionEvaluator getInstance() {
56 return getInstance(null);
57 }
58
59
65 public final static ExpressionEvaluator getInstance(String name) {
66 assert DEFAULT_FACTORY != null;
67 assert FACTORY_MAP != null;
68
69 if(name == null)
70 return DEFAULT_FACTORY.getInstance();
71 else if(FACTORY_MAP.containsKey(name))
72 return ((ExpressionEngineFactory)FACTORY_MAP.get(name)).getInstance();
73
74 String msg = "An ExpressionEvaluator named \"" + name + "\" is not available.";
75 if(_logger.isErrorEnabled())
76 _logger.error(msg);
77
78 throw new IllegalArgumentException (msg);
79 }
80
81 private static final ExpressionEngineFactory initialize(Map factoryMap) {
82 assert factoryMap != null;
83
84 NetuiConfig config = ConfigUtil.getConfig();
85 assert config != null;
86
87 ExpressionLanguages languages = config.getExpressionLanguages();
88 assert languages != null;
89
90 ExpressionLanguage[] array = languages.getExpressionLanguageArray();
91 assert array != null;
92
93 for(int i = 0; i < array.length; i++) {
94 String name = array[i].getName();
95 String className = array[i].getFactoryClass();
96
97 ExpressionEngineFactory factory = null;
98 try {
99 Class type = Class.forName(className);
100 factory = (ExpressionEngineFactory)type.newInstance();
101 } catch(ClassNotFoundException cnf) {
102 if(_logger.isWarnEnabled())
103 _logger.warn("Could not create an ExpressionEngineFactory for type \"" + className +
104 "\" because the implementation class could not be found.");
105
106 continue;
107 } catch(Exception ex) {
108 assert ex instanceof IllegalAccessException || ex instanceof InstantiationException ;
109
110 if(_logger.isWarnEnabled())
111 _logger.warn("Could not create an ExpressionEngineFactory for type \"" + className +
112 "\" because an error occurred creating the factory. Cause: " + ex, ex);
113 continue;
114 }
115
116 if(factoryMap.containsKey(name))
117 if(_logger.isWarnEnabled())
118 _logger.warn("Overwriting a previously defined ExpressionEngineFactory named \"" + name +
119 "\" with a new ExpressionEngineFactory of type \"" + className + "\"");
120 else
121 _logger.info("Adding an ExpressionEngineFactory named \"" + name + "\" with implementation \"" + className + "\"");
122
123 factoryMap.put(name, factory);
124 }
125
126 ExpressionEngineFactory defaultEngineFactory = null;
127 String defaultLanguage = languages.getDefaultLanguage();
128 if(defaultLanguage != null) {
129 defaultEngineFactory = (ExpressionEngineFactory)factoryMap.get(defaultLanguage);
130 if(defaultEngineFactory != null) {
131 if(_logger.isInfoEnabled())
132 _logger.info("Using a default expression evaluator of type \"" + factoryMap.get(defaultLanguage).getClass().getName() + "\"");
133 } else {
134 String msg =
135 "The default ExpressionEvaluator named \"" + defaultLanguage + "\" was specified, but the ExpressionEngineFactory could not be found.";
136 if(_logger.isWarnEnabled()) _logger.warn(msg);
137
138 throw new RuntimeException (msg);
139 }
140 } else {
141 String msg = "There is no default expression engine specified.";
142 if(_logger.isErrorEnabled()) _logger.error(msg);
143 throw new RuntimeException (msg);
144 }
145
146 return defaultEngineFactory;
147 }
148 }
149 |
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