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XWork is an command-pattern framework that is used to power WebWork
as well as other applications. XWork provides an Inversion of Control
container, a powerful expression language, data type conversion,
validation, and pluggable configuration.
/*
* Copyright (c) 2002-2006 by OpenSymphony
* All rights reserved.
*/
package com.opensymphony.xwork2.interceptor;
import java.util.Iterator;
import java.util.Map;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.config.entities.ActionConfig;
import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
/**
*
*
* The aim of this Interceptor is to alias a named parameter to a different named parameter. By acting as the glue
* between actions sharing similiar parameters (but with different names), it can help greatly with action chaining.
*
* Action's alias expressions should be in the form of #{ "name1" : "alias1", "name2" : "alias2" }.
* This means that assuming an action (or something else in the stack) has a value for the expression named name1 and the
* action this interceptor is applied to has a setter named alias1, alias1 will be set with the value from
* name1.
*
*
*
* Interceptor parameters:
*
*
*
*
*
* - aliasesKey (optional) - the name of the action parameter to look for the alias map (by default this is
* aliases).
*
*
*
*
*
* Extending the interceptor:
*
*
*
*
*
* This interceptor does not have any known extension points.
*
*
*
* Example code:
*
*
*
* <action name="someAction" class="com.examples.SomeAction">
* <!-- The value for the foo parameter will be applied as if it were named bar -->
* <param name="aliases">#{ 'foo' : 'bar' }</param>
*
* <interceptor-ref name="alias"/>
* <interceptor-ref name="basicStack"/>
* <result name="success">good_result.ftl</result>
* </action>
*
*
*
* @author Matthew Payne
*/
public class AliasInterceptor extends AbstractInterceptor {
private static final Logger log = LoggerFactory.getLogger(AliasInterceptor.class);
private static final String DEFAULT_ALIAS_KEY = "aliases";
protected String aliasesKey = DEFAULT_ALIAS_KEY;
/**
* Sets the name of the action parameter to look for the alias map.
*
* Default is aliases.
*
* @param aliasesKey the name of the action parameter
*/
public void setAliasesKey(String aliasesKey) {
this.aliasesKey = aliasesKey;
}
public String intercept(ActionInvocation invocation) throws Exception {
ActionConfig config = invocation.getProxy().getConfig();
ActionContext ac = invocation.getInvocationContext();
// get the action's parameters
final Map parameters = config.getParams();
if (parameters.containsKey(aliasesKey)) {
String aliasExpression = (String) parameters.get(aliasesKey);
ValueStack stack = ac.getValueStack();
Object obj = stack.findValue(aliasExpression);
if (obj != null && obj instanceof Map) {
// override
Map aliases = (Map) obj;
Iterator itr = aliases.entrySet().iterator();
while (itr.hasNext()) {
Map.Entry entry = (Map.Entry) itr.next();
String name = entry.getKey().toString();
String alias = (String) entry.getValue();
Object value = stack.findValue(name);
if (null == value) {
// workaround
Map contextParameters = (Map) stack.getContext().get("parameters");
if (null != contextParameters) {
value = contextParameters.get(name);
}
}
if (null != value) {
stack.setValue(alias, value);
}
}
} else {
log.debug("invalid alias expression:" + aliasesKey);
}
}
return invocation.invoke();
}
}