freemarker.template.utility.CaptureOutput Maven / Gradle / Ivy
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* 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 freemarker.template.utility;
import java.io.IOException;
import java.io.Writer;
import java.util.Map;
import freemarker.core.Environment;
import freemarker.template.SimpleScalar;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateScalarModel;
import freemarker.template.TemplateTransformModel;
/**
* A transform that captures the output of a block of FTL code and stores that in a variable.
*
* As this transform is initially present in the shared variable set, you can always
* access it from the templates:
*
*
* <@capture_output var="captured">
* ...
* </@capture_output>
*
*
* And later in the template you can use the captured output:
*
* ${captured}
*
* This transform requires one of three parameters: var, local, or global.
* Each of them specifies the name of the variable that stores the captured output, but the first creates a
* variable in a name-space (as <#assign>), the second creates a macro-local variable (as <#local>),
* and the last creates a global variable (as <#global>).
*
* In the case of an assignment within a namespace, there is an optional parameter
* namespace that indicates in which namespace to do the assignment.
* if this is omitted, the current namespace is used, and this will be, by far, the most
* common usage pattern.
*
* @deprecated Use block-assignments instead, like <assign x>...</assign>.
*/
@Deprecated
public class CaptureOutput implements TemplateTransformModel {
@Override
public Writer getWriter(final Writer out, final Map args) throws TemplateModelException {
String errmsg = "Must specify the name of the variable in "
+ "which to capture the output with the 'var' or 'local' or 'global' parameter.";
if (args == null) throw new TemplateModelException(errmsg);
boolean local = false, global = false;
final TemplateModel nsModel = (TemplateModel) args.get("namespace");
Object varNameModel = args.get("var");
if (varNameModel == null) {
varNameModel = args.get("local");
if (varNameModel == null) {
varNameModel = args.get("global");
global = true;
} else {
local = true;
}
if (varNameModel == null) {
throw new TemplateModelException(errmsg);
}
}
if (args.size() == 2) {
if (nsModel == null) {
throw new TemplateModelException("Second parameter can only be namespace");
}
if (local) {
throw new TemplateModelException("Cannot specify namespace for a local assignment");
}
if (global) {
throw new TemplateModelException("Cannot specify namespace for a global assignment");
}
if (!(nsModel instanceof Environment.Namespace)) {
throw new TemplateModelException("namespace parameter does not specify a namespace. It is a " + nsModel.getClass().getName());
}
} else if (args.size() != 1) throw new TemplateModelException(
"Bad parameters. Use only one of 'var' or 'local' or 'global' parameters.");
if (!(varNameModel instanceof TemplateScalarModel)) {
throw new TemplateModelException("'var' or 'local' or 'global' parameter doesn't evaluate to a string");
}
final String varName = ((TemplateScalarModel) varNameModel).getAsString();
if (varName == null) {
throw new TemplateModelException("'var' or 'local' or 'global' parameter evaluates to null string");
}
final StringBuilder buf = new StringBuilder();
final Environment env = Environment.getCurrentEnvironment();
final boolean localVar = local;
final boolean globalVar = global;
return new Writer() {
@Override
public void write(char cbuf[], int off, int len) {
buf.append(cbuf, off, len);
}
@Override
public void flush() throws IOException {
out.flush();
}
@Override
public void close() throws IOException {
SimpleScalar result = new SimpleScalar(buf.toString());
try {
if (localVar) {
env.setLocalVariable(varName, result);
} else if (globalVar) {
env.setGlobalVariable(varName, result);
} else {
if (nsModel == null) {
env.setVariable(varName, result);
} else {
((Environment.Namespace) nsModel).put(varName, result);
}
}
} catch (java.lang.IllegalStateException ise) { // if somebody uses 'local' outside a macro
throw new IOException("Could not set variable " + varName + ": " + ise.getMessage());
}
}
};
}
}