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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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package org.apache.cayenne.access.jdbc;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.context.InternalContextAdapterImpl;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.RuntimeInstance;
import org.apache.velocity.runtime.log.NullLogSystem;
import org.apache.velocity.runtime.parser.ParseException;
import org.apache.velocity.runtime.parser.node.SimpleNode;
/**
* Processor for SQL velocity templates.
*
* @see org.apache.cayenne.query.SQLTemplate
* @since 1.1
* @author Andrus Adamchik
*/
class SQLTemplateProcessor {
private static RuntimeInstance sharedRuntime;
static final String BINDINGS_LIST_KEY = "bindings";
static final String RESULT_COLUMNS_LIST_KEY = "resultColumns";
static final String HELPER_KEY = "helper";
private static final SQLTemplateRenderingUtils sharedUtils = new SQLTemplateRenderingUtils();
RuntimeInstance velocityRuntime;
SQLTemplateRenderingUtils renderingUtils;
static {
initVelocityRuntime();
}
private static void initVelocityRuntime() {
// init static velocity engine
sharedRuntime = new RuntimeInstance();
// set null logger
sharedRuntime.addProperty(
RuntimeConstants.RUNTIME_LOG_LOGSYSTEM,
new NullLogSystem());
sharedRuntime.addProperty(
RuntimeConstants.RESOURCE_MANAGER_CLASS,
SQLTemplateResourceManager.class.getName());
sharedRuntime.addProperty("userdirective", BindDirective.class.getName());
sharedRuntime.addProperty("userdirective", BindEqualDirective.class.getName());
sharedRuntime.addProperty("userdirective", BindNotEqualDirective.class.getName());
sharedRuntime.addProperty("userdirective", BindObjectEqualDirective.class.getName());
sharedRuntime.addProperty("userdirective", BindObjectNotEqualDirective.class.getName());
sharedRuntime.addProperty("userdirective", ResultDirective.class.getName());
sharedRuntime.addProperty("userdirective", ChainDirective.class.getName());
sharedRuntime.addProperty("userdirective", ChunkDirective.class.getName());
try {
sharedRuntime.init();
}
catch (Exception ex) {
throw new CayenneRuntimeException(
"Error setting up Velocity RuntimeInstance.",
ex);
}
}
SQLTemplateProcessor() {
this.velocityRuntime = sharedRuntime;
this.renderingUtils = sharedUtils;
}
SQLTemplateProcessor(RuntimeInstance velocityRuntime,
SQLTemplateRenderingUtils renderingUtils) {
this.velocityRuntime = velocityRuntime;
this.renderingUtils = renderingUtils;
}
/**
* Builds and returns a SQLStatement based on SQL template and a set of parameters.
* During rendering, VelocityContext exposes the following as variables: all
* parameters in the map, {@link SQLTemplateRenderingUtils} as a "helper" variable and
* SQLStatement object as "statement" variable.
*/
SQLStatement processTemplate(String template, Map parameters) throws Exception {
// have to make a copy of parameter map since we are gonna modify it..
Map internalParameters = (parameters != null && !parameters.isEmpty())
? new HashMap(parameters)
: new HashMap(3);
List bindings = new ArrayList();
List results = new ArrayList();
internalParameters.put(BINDINGS_LIST_KEY, bindings);
internalParameters.put(RESULT_COLUMNS_LIST_KEY, results);
internalParameters.put(HELPER_KEY, renderingUtils);
String sql = buildStatement(
new VelocityContext(internalParameters),
template,
parameters);
ParameterBinding[] bindingsArray = new ParameterBinding[bindings.size()];
bindings.toArray(bindingsArray);
ColumnDescriptor[] resultsArray = new ColumnDescriptor[results.size()];
results.toArray(resultsArray);
return new SQLStatement(sql, resultsArray, bindingsArray);
}
String buildStatement(VelocityContext context, String template, Map parameters)
throws Exception {
// Note: this method is a reworked version of
// org.apache.velocity.app.Velocity.evaluate(..)
// cleaned up to avoid using any Velocity singletons
StringWriter out = new StringWriter(template.length());
SimpleNode nodeTree = null;
try {
nodeTree = velocityRuntime.parse(new StringReader(template), template);
}
catch (ParseException pex) {
throw new CayenneRuntimeException("Error parsing template '"
+ template
+ "' : "
+ pex.getMessage());
}
if (nodeTree == null) {
throw new CayenneRuntimeException("Error parsing template " + template);
}
// ... not sure what InternalContextAdapter is for...
InternalContextAdapterImpl ica = new InternalContextAdapterImpl(context);
ica.pushCurrentTemplateName(template);
try {
nodeTree.init(ica, velocityRuntime);
nodeTree.render(ica, out);
return out.toString();
}
finally {
ica.popCurrentTemplateName();
}
}
}