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18 package org.apache.activemq.filter;
19
20 import java.io.IOException  ;
21 import java.lang.reflect.Constructor ;
22 import java.lang.reflect.InvocationTargetException ;
23
24 import javax.jms.JMSException ;
25
26 import org.apache.activemq.command.Message;
27 import org.apache.activemq.util.JMSExceptionSupport;
28 import org.apache.commons.logging.Log;
29 import org.apache.commons.logging.LogFactory;
30
31
34 public final class XPathExpression implements BooleanExpression {
35
36 private static final Log log = LogFactory.getLog(XPathExpression.class);
37 private static final String EVALUATOR_SYSTEM_PROPERTY = "org.apache.activemq.XPathEvaluatorClassName";
38 private static final String DEFAULT_EVALUATOR_CLASS_NAME=XalanXPathEvaluator.class.getName();
39
40 private static final Constructor EVALUATOR_CONSTRUCTOR;
41
42 static {
43 String cn = System.getProperty(EVALUATOR_SYSTEM_PROPERTY, DEFAULT_EVALUATOR_CLASS_NAME);
44 Constructor m = null;
45 try {
46 try {
47 m = getXPathEvaluatorConstructor(cn);
48 } catch (Throwable e) {
49 log.warn("Invalid "+XPathEvaluator.class.getName()+" implementation: "+cn+", reason: "+e,e);
50 cn = DEFAULT_EVALUATOR_CLASS_NAME;
51 try {
52 m = getXPathEvaluatorConstructor(cn);
53 } catch (Throwable e2) {
54 log.error("Default XPath evaluator could not be loaded",e);
55 }
56 }
57 } finally {
58 EVALUATOR_CONSTRUCTOR = m;
59 }
60 }
61
62 private static Constructor getXPathEvaluatorConstructor(String cn) throws ClassNotFoundException , SecurityException , NoSuchMethodException {
63 Class c = XPathExpression.class.getClassLoader().loadClass(cn);
64 if( !XPathEvaluator.class.isAssignableFrom(c) ) {
65 throw new ClassCastException (""+c+" is not an instance of "+XPathEvaluator.class);
66 }
67 return c.getConstructor(new Class []{String .class});
68 }
69
70 private final String xpath;
71 private final XPathEvaluator evaluator;
72
73 static public interface XPathEvaluator {
74 public boolean evaluate(Message message) throws JMSException ;
75 }
76
77 XPathExpression(String xpath) {
78 this.xpath = xpath;
79 this.evaluator = createEvaluator(xpath);
80 }
81
82 private XPathEvaluator createEvaluator(String xpath2) {
83 try {
84 return (XPathEvaluator)EVALUATOR_CONSTRUCTOR.newInstance(new Object []{xpath});
85 } catch (InvocationTargetException e) {
86 Throwable cause = e.getCause();
87 if( cause instanceof RuntimeException ) {
88 throw (RuntimeException )cause;
89 }
90 throw new RuntimeException ("Invalid XPath Expression: "+xpath+" reason: "+e.getMessage(), e);
91 } catch (Throwable e) {
92 throw new RuntimeException ("Invalid XPath Expression: "+xpath+" reason: "+e.getMessage(), e);
93 }
94 }
95
96 public Object evaluate(MessageEvaluationContext message) throws JMSException {
97 try {
98 if( message.isDropped() )
99 return null;
100 return evaluator.evaluate(message.getMessage()) ? Boolean.TRUE : Boolean.FALSE;
101 } catch (IOException e) {
102 throw JMSExceptionSupport.create(e);
103 }
104
105 }
106
107 public String toString() {
108 return "XPATH "+ConstantExpression.encodeString(xpath);
109 }
110
111
116 public boolean matches(MessageEvaluationContext message) throws JMSException {
117 Object object = evaluate(message);
118 return object!=null && object==Boolean.TRUE;
119 }
120
121 }
122 |
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