Struts example source code file (I18nInterceptor.java)

This example Struts source code file (I18nInterceptor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

default_parameter, default_requestonly_parameter, default_session_attribute, i18ninterceptor, i18ninterceptor, locale, locale, log, map, object, object, override, string, string, util

The Struts I18nInterceptor.java source code

/*
 * Copyright 2002-2006,2009 The Apache Software Foundation.
 * 
 * Licensed 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 com.opensymphony.xwork2.interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.util.LocalizedTextUtil;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

import java.util.Locale;
import java.util.Map;

/**
 * <!-- START SNIPPET: description -->
 * <p/>
 * An interceptor that handles setting the locale specified in a session as the locale for the current action request.
 * In addition, this interceptor will look for a specific HTTP request parameter and set the locale to whatever value is
 * provided. This means that this interceptor can be used to allow for your application to dynamically change the locale
 * for the user's session or, alternatively, only for the current request (since XWork 2.1.3).
 * This is very useful for applications that require multi-lingual support and want the user to
 * be able to set his or her language preference at any point. The locale parameter is removed during the execution of
 * this interceptor, ensuring that properties aren't set on an action (such as request_locale) that have no typical
 * corresponding setter in your action.
 * <p/>
 * <p/>For example, using the default parameter name, a request to foo.action?request_locale=en_US, then the
 * locale for US English is saved in the user's session and will be used for all future requests.
 * <p/>
 * <!-- END SNIPPET: description -->
 * <p/>
 * <p/> Interceptor parameters:
 * <p/>
 * <!-- START SNIPPET: parameters -->
 * <p/>
 * <ul>
 * <p/>
 * <li>parameterName (optional) - the name of the HTTP request parameter that dictates the locale to switch to and save
 * in the session. By default this is <b>request_locale
 * <p/>
 * <li>requestOnlyParameterName (optional) - the name of the HTTP request parameter that dictates the locale to switch to
 * for the current request only, without saving it in the session. By default this is <b>request_only_locale
 * <p/>
 * <li>attributeName (optional) - the name of the session key to store the selected locale. By default this is
 * <b>WW_TRANS_I18N_LOCALE
 * <p/>
 * </ul>
 * <p/>
 * <!-- END SNIPPET: parameters -->
 * <p/>
 * <p/> Extending the interceptor:
 * <p/>
 * <p/>
 * <p/>
 * <!-- START SNIPPET: extending -->
 * <p/>
 * There are no known extensions points for this interceptor.
 * <p/>
 * <!-- END SNIPPET: extending -->
 * <p/>
 * <p/> Example code:
 * <p/>
 * <pre>
 * <!-- START SNIPPET: example -->
 * <action name="someAction" class="com.examples.SomeAction">
 *     <interceptor-ref name="i18n"/>
 *     <interceptor-ref name="basicStack"/>
 *     <result name="success">good_result.ftl</result>
 * </action>
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 * @author Aleksei Gopachenko
 */
public class I18nInterceptor extends AbstractInterceptor {
    protected static final Logger LOG = LoggerFactory.getLogger(I18nInterceptor.class);

    public static final String DEFAULT_SESSION_ATTRIBUTE = "WW_TRANS_I18N_LOCALE";
    public static final String DEFAULT_PARAMETER = "request_locale";
    public static final String DEFAULT_REQUESTONLY_PARAMETER = "request_only_locale";

    protected String parameterName = DEFAULT_PARAMETER;
    protected String requestOnlyParameterName = DEFAULT_REQUESTONLY_PARAMETER;
    protected String attributeName = DEFAULT_SESSION_ATTRIBUTE;

    public I18nInterceptor() {
        if (LOG.isDebugEnabled()) {
            LOG.debug("new I18nInterceptor()");
        }
    }

    public void setParameterName(String parameterName) {
        this.parameterName = parameterName;
    }

    public void setRequestOnlyParameterName(String requestOnlyParameterName) {
        this.requestOnlyParameterName = requestOnlyParameterName;
    }

    public void setAttributeName(String attributeName) {
        this.attributeName = attributeName;
    }

    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        if (LOG.isDebugEnabled()) {
            LOG.debug("intercept '"
                    + invocation.getProxy().getNamespace() + "/"
                    + invocation.getProxy().getActionName() + "' { ");
        }
        //get requested locale
        Map<String, Object> params = invocation.getInvocationContext().getParameters();

        boolean storeInSession = true;
        Object requested_locale = findLocaleParameter(params, parameterName);
        if (requested_locale == null) {
            requested_locale = findLocaleParameter(params, requestOnlyParameterName);
            if (requested_locale != null) {
                storeInSession = false;
            }
        }

        //save it in session
        Map<String, Object> session = invocation.getInvocationContext().getSession();

        Locale locale = null;
        if (requested_locale != null) {
            locale = (requested_locale instanceof Locale) ?
                    (Locale) requested_locale : LocalizedTextUtil.localeFromString(requested_locale.toString(), null);
            if (locale != null && LOG.isDebugEnabled()) {
                LOG.debug("applied request locale=" + locale);
            }
        }
        if (session != null) {
            synchronized (session) {
                if (locale == null) {
                    storeInSession = false;
                    // check session for saved locale
                    Object sessionLocale = session.get(attributeName);
                    if (sessionLocale != null && sessionLocale instanceof Locale) {
                        locale = (Locale) sessionLocale;
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("applied session locale=" + locale);
                        }
                    } else {
                        // no overriding locale definition found, stay with current invocation (=browser) locale
                        locale = invocation.getInvocationContext().getLocale();
                        if (locale != null && LOG.isDebugEnabled()) {
                            LOG.debug("applied invocation context locale=" + locale);
                        }
                    }
                }
                if (storeInSession) {
                    session.put(attributeName, locale);
                }
            }
        }
        saveLocale(invocation, locale);

        if (LOG.isDebugEnabled()) {
            LOG.debug("before Locale=" + invocation.getStack().findValue("locale"));
        }

        final String result = invocation.invoke();
        if (LOG.isDebugEnabled()) {
            LOG.debug("after Locale=" + invocation.getStack().findValue("locale"));
        }

        if (LOG.isDebugEnabled()) {
            LOG.debug("intercept } ");
        }

        return result;
    }

    private Object findLocaleParameter(Map<String, Object> params, String parameterName) {
        Object requested_locale = params.remove(parameterName);
        if (requested_locale != null && requested_locale.getClass().isArray()
                && ((Object[]) requested_locale).length == 1) {
            requested_locale = ((Object[]) requested_locale)[0];

            if (LOG.isDebugEnabled()) {
                LOG.debug("requested_locale=" + requested_locale);
            }
        }
        return requested_locale;
    }

    /**
     * Save the given locale to the ActionInvocation.
     *
     * @param invocation The ActionInvocation.
     * @param locale     The locale to save.
     */
    protected void saveLocale(ActionInvocation invocation, Locale locale) {
        invocation.getInvocationContext().setLocale(locale);
    }

}