001/**
002The contents of this file are subject to the Mozilla Public License Version 1.1 
003(the "License"); you may not use this file except in compliance with the License. 
004You may obtain a copy of the License at http://www.mozilla.org/MPL/ 
005Software distributed under the License is distributed on an "AS IS" basis, 
006WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the 
007specific language governing rights and limitations under the License. 
008
009The Original Code is "ValidationContextFactory.java".  Description: 
010"Source of ValidationContext" 
011
012The Initial Developer of the Original Code is University Health Network. Copyright (C) 
0132004.  All Rights Reserved. 
014
015Contributor(s): ______________________________________. 
016
017Alternatively, the contents of this file may be used under the terms of the 
018GNU General Public License (the "GPL"), in which case the provisions of the GPL are 
019applicable instead of those above.  If you wish to allow use of your version of this 
020file only under the terms of the GPL and not to allow others to use your version 
021of this file under the MPL, indicate your decision by deleting  the provisions above 
022and replace  them with the notice and other provisions required by the GPL License.  
023If you do not delete the provisions above, a recipient may use your version of 
024this file under either the MPL or the GPL. 
025 */
026package ca.uhn.hl7v2.validation.impl;
027
028import ca.uhn.hl7v2.HL7Exception;
029import ca.uhn.hl7v2.util.ReflectionUtil;
030import ca.uhn.hl7v2.validation.ValidationContext;
031import ca.uhn.hl7v2.validation.ValidationException;
032import ca.uhn.hl7v2.validation.builder.ValidationRuleBuilder;
033import ca.uhn.hl7v2.validation.builder.support.DefaultValidationBuilder;
034import ca.uhn.hl7v2.validation.builder.support.NoValidationBuilder;
035
036/**
037 * <p>
038 * The <code>ValidationContext</code> returned by <code>getContext()</code> is
039 * determined by the system property "ca.uhn.hl7v2.validation.context_class".
040 * This factory defines two inner classes that can be used: DefaultValidation
041 * and NoValidation. You can also create your own context, setting whatever
042 * rules you want in its constructor, and reference it instead (it must have a
043 * zero-arg constructor). If this property is not set, DefaultValidation is
044 * used.
045 * </p>
046 * 
047 * <p>
048 * Also note that the contexts provided here use
049 * <code>ValidationContextImpl</code>, so rule bindings can be added or removed
050 * programmatically from the starting set.
051 * </p>
052 * 
053 * @author Bryan Tripp
054 * @author Christian Ohr
055 * 
056 */
057public class ValidationContextFactory {
058
059    private static ValidationContext ourContext;
060
061    public static final String CONTEXT_PROPERTY = "ca.uhn.hl7v2.validation.context_class";
062
063    /**
064     * Returns a singleton <code>ValidationContext</code>, creating it if
065     * necessary.
066     * 
067     * @return <code>ValidationContext</code>
068     */
069    public synchronized static ValidationContext getContext() throws HL7Exception {
070        if (ourContext == null) {
071            String contextClassName = System.getProperty(CONTEXT_PROPERTY);
072            ourContext = contextClassName == null ? defaultValidation()
073                    : customValidation(contextClassName);
074        }
075        return ourContext;
076    }
077
078    /**
079     * @return an instance of a non-validating context
080     */
081    @SuppressWarnings("unchecked")
082        public static <T extends ValidationContext> T noValidation() {
083        return (T) new ValidationContextImpl(new NoValidationBuilder());
084    }
085
086    /**
087     * @return an instance of a default validation context
088     */
089    @SuppressWarnings("unchecked")
090        public static <T extends ValidationContext> T defaultValidation() {
091        return (T)new ValidationContextImpl(new DefaultValidationBuilder());
092    }
093
094    /**
095     * @param ruleBuilderClassName class name of a {@link ValidationRuleBuilder}
096     *            subclass
097     * @return a validation rule builder instance
098     * @throws HL7Exception if builder cannot be built
099     */
100    @SuppressWarnings("unchecked")
101    public static ValidationRuleBuilder customBuilder(String ruleBuilderClassName)
102            throws HL7Exception {
103        Class<? extends ValidationRuleBuilder> c;
104        try {
105            c = (Class<? extends ValidationRuleBuilder>) Class.forName(ruleBuilderClassName);
106        } catch (ClassNotFoundException e) {
107            throw new HL7Exception(e);
108        }
109        return ReflectionUtil.instantiate(c);
110    }
111
112    public static ValidationContext fromBuilder(String ruleBuilderClassName) throws HL7Exception {
113        return new ValidationContextImpl(customBuilder(ruleBuilderClassName));
114    }
115
116    public static ValidationContext fromBuilder(ValidationRuleBuilder builder) {
117        return new ValidationContextImpl(builder);
118    }
119
120    /**
121     * @param contextClassName class name of a {@link ValidationContext}
122     *            subclass
123     * @return instance of the ValidationContext
124     * @throws HL7Exception if context cannot be obtained
125     */
126    @SuppressWarnings("unchecked")
127    public static ValidationContext customValidation(String contextClassName) throws HL7Exception {
128        Class<? extends ValidationContext> c;
129        try {
130            c = (Class<? extends ValidationContext>) Class.forName(contextClassName);
131        } catch (Exception e) {
132            throw new HL7Exception(e);
133        }
134        return ReflectionUtil.instantiate(c);
135
136    }
137
138}