GetAsStringModel.java
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* 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
* under the License.
*/
package org.apache.tiles.template;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.tiles.api.Attribute;
import org.apache.tiles.api.TilesContainer;
import org.apache.tiles.api.access.TilesAccess;
import org.apache.tiles.autotag.core.runtime.ModelBody;
import org.apache.tiles.autotag.core.runtime.annotation.Parameter;
import org.apache.tiles.request.Request;
import java.io.IOException;
import java.io.Writer;
import java.util.Deque;
/**
* <p>
* <strong> Render the value of the specified template attribute to the current
* Writer</strong>
* </p>
*
* <p>
* Retrieve the value of the specified template attribute property, and render
* it to the current Writer as a String. The usual toString() conversions is
* applied on found value.
* </p>
*
* @since 2.2.0
*/
public class GetAsStringModel {
/**
* The logging object.
*/
private static final Logger LOG = LogManager.getLogger(GetAsStringModel.class);
/**
* The attribute resolver to use.
*/
private final AttributeResolver attributeResolver;
/**
* Constructor that uses the defaut attribute resolver.
*
* @since 3.0.0
*/
public GetAsStringModel() {
this(new DefaultAttributeResolver());
}
/**
* Constructor.
*
* @param attributeResolver The attribute resolver to use.
* @since 2.2.0
*/
public GetAsStringModel(AttributeResolver attributeResolver) {
this.attributeResolver = attributeResolver;
}
/**
* Executes the operation.
*
* @param ignore If <code>true</code>, if an exception happens during
* rendering, of if the attribute is null, the problem will be ignored.
* @param preparer The preparer to invoke before rendering the attribute.
* @param role A comma-separated list of roles. If present, the attribute
* will be rendered only if the current user belongs to one of the roles.
* @param defaultValue The default value of the attribute. To use only if
* the attribute was not computed.
* @param defaultValueRole The default comma-separated list of roles. To use
* only if the attribute was not computed.
* @param defaultValueType The default type of the attribute. To use only if
* the attribute was not computed.
* @param name The name of the attribute.
* @param value The attribute to use immediately, if not null.
* @param request The request.
* @param modelBody The body.
* @throws IOException If an I/O error happens during rendering.
* @since 2.2.0
*/
public void execute(
boolean ignore,
String preparer,
String role,
Object defaultValue,
String defaultValueRole,
String defaultValueType,
@Parameter(required = true) String name,
Attribute value,
Request request,
ModelBody modelBody
) throws IOException {
TilesContainer container = TilesAccess.getCurrentContainer(request);
Deque<Object> composeStack = ComposeStackUtil.getComposeStack(request);
Attribute attribute = resolveAttribute(
container,
ignore,
preparer,
role,
defaultValue,
defaultValueRole,
defaultValueType,
name,
value,
request
);
if (attribute != null) {
composeStack.push(attribute);
}
modelBody.evaluateWithoutWriting();
container = TilesAccess.getCurrentContainer(request);
Writer writer = request.getWriter();
if (attribute != null) {
attribute = (Attribute) composeStack.pop();
}
renderAttribute(attribute, container, writer, ignore, request);
}
/**
* Resolves the attribute. and starts the context.
*
* @param container The Tiles container to use.
* @param ignore If <code>true</code>, if an exception happens during
* rendering, of if the attribute is null, the problem will be ignored.
* @param preparer The preparer to invoke before rendering the attribute.
* @param role A comma-separated list of roles. If present, the attribute
* will be rendered only if the current user belongs to one of the roles.
* @param defaultValue The default value of the attribute. To use only if
* the attribute was not computed.
* @param defaultValueRole The default comma-separated list of roles. To use
* only if the attribute was not computed.
* @param defaultValueType The default type of the attribute. To use only if
* the attribute was not computed.
* @param name The name of the attribute.
* @param value The attribute to use immediately, if not null.
* @param request The request.
* @return The resolved attribute.
*/
private Attribute resolveAttribute(
TilesContainer container,
boolean ignore,
String preparer,
String role,
Object defaultValue,
String defaultValueRole,
String defaultValueType,
String name,
Attribute value,
Request request
) {
if (preparer != null) {
container.prepare(preparer, request);
}
Attribute attribute = attributeResolver.computeAttribute(
container,
value,
name,
role,
ignore,
defaultValue,
defaultValueRole,
defaultValueType,
request
);
container.startContext(request);
return attribute;
}
/**
* Renders the attribute as a string.
*
* @param attribute The attribute to use, previously resolved.
* @param container The Tiles container to use.
* @param writer The writer into which the attribute will be written.
* @param ignore If <code>true</code>, if an exception happens during
* rendering, of if the attribute is null, the problem will be ignored.
* @param request The request.
* @throws IOException If an I/O error happens during rendering.
*/
private void renderAttribute(
Attribute attribute,
TilesContainer container,
Writer writer,
boolean ignore,
Request request
) throws IOException {
try {
if (attribute == null && ignore) {
return;
}
Object value = container.evaluate(attribute, request);
if (value != null) {
writer.write(value.toString());
}
} catch (IOException | RuntimeException e) {
if (!ignore) {
throw e;
} else if (LOG.isDebugEnabled()) {
LOG.debug("Ignoring exception", e);
}
} finally {
container.endContext(request);
}
}
}