com.sun.faces.util.ScopedRunner Maven / Gradle / Ivy
/*
* Copyright (c) 2021 Contributors to Eclipse Foundation.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package com.sun.faces.util;
import java.util.HashMap;
import java.util.Map;
import jakarta.faces.context.FacesContext;
/**
* This class helps in letting code run within its own scope. Such scope is defined by specific variables being
* available to EL within it. The request scope is used to store the variables.
*
* @author Arjan Tijms
*
*/
public class ScopedRunner {
private FacesContext context;
private Map scopedVariables;
private Map previousVariables = new HashMap<>();
public ScopedRunner(FacesContext context) {
this(context, new HashMap<>());
}
public ScopedRunner(FacesContext context, Map scopedVariables) {
this.context = context;
this.scopedVariables = scopedVariables;
}
/**
* Adds the given variable to this instance. Can be used in a builder-pattern.
*
* @param key the key name of the variable
* @param value the value of the variable
* @return this ScopedRunner, so adding variables and finally calling invoke can be chained.
*/
public ScopedRunner with(String key, Object value) {
scopedVariables.put(key, value);
return this;
}
/**
* Invokes the callback within the scope of the variables being given in the constructor.
* @param callback The callback.
*/
public void invoke(Runnable callback) {
try {
setNewScope();
callback.run();
} finally {
restorePreviousScope();
}
}
private void setNewScope() {
previousVariables.clear();
Map requestMap = context.getExternalContext().getRequestMap();
for (Map.Entry entry : scopedVariables.entrySet()) {
Object previousVariable = requestMap.put(entry.getKey(), entry.getValue());
if (previousVariable != null) {
previousVariables.put(entry.getKey(), previousVariable);
}
}
}
private void restorePreviousScope() {
try {
Map requestMap = context.getExternalContext().getRequestMap();
for (Map.Entry entry : scopedVariables.entrySet()) {
Object previousVariable = previousVariables.get(entry.getKey());
if (previousVariable != null) {
requestMap.put(entry.getKey(), previousVariable);
} else {
requestMap.remove(entry.getKey());
}
}
} finally {
previousVariables.clear();
}
}
}