i18ninterceptor.java

在Struts2中的jar包xwork的源代码.版本为2.0.7

/*
 * Copyright (c) 2002-2006 by OpenSymphony
 * All rights reserved.
 */

package com.opensymphony.xwork2.interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.util.LocalizedTextUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

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

/**
 * <!-- START SNIPPET: description -->
 *
 * 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. 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/>For example, using the default parameter name, a request to <b>foo.action?request_locale=en_US</b>, then the
 * locale for US English is saved in the user's session and will be used for all future requests.
 *
 * <!-- END SNIPPET: description -->
 *
 * <p/> <u>Interceptor parameters:</u>
 *
 * <!-- START SNIPPET: parameters -->
 *
 * <ul>
 *
 * <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</b></li>
 *
 * <li>attributeName (optional) - the name of the session key to store the selected locale. By default this is
 * <b>WW_TRANS_I18N_LOCALE</b></li>
 *
 * </ul>
 *
 * <!-- END SNIPPET: parameters -->
 *
 * <p/> <u>Extending the interceptor:</u>
 *
 * <p/>
 *
 * <!-- START SNIPPET: extending -->
 *
 * There are no known extensions points for this interceptor.
 *
 * <!-- END SNIPPET: extending -->
 *
 * <p/> <u>Example code:</u>
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
 *     &lt;interceptor-ref name="i18n"/&gt;
 *     &lt;interceptor-ref name="basicStack"/&gt;
 *     &lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
 * &lt;/action&gt;
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 * @author Aleksei Gopachenko
 */
public class I18nInterceptor extends AbstractInterceptor {
    protected static final Log log = LogFactory.getLog(I18nInterceptor.class);

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

    protected String parameterName = DEFAULT_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 setAttributeName(String attributeName) {
        this.attributeName = attributeName;
    }

    public String intercept(ActionInvocation invocation) throws Exception {
        if (log.isDebugEnabled()) {
            log.debug("intercept '"
                    + invocation.getProxy().getNamespace() + "/"
                    + invocation.getProxy().getActionName() + "' { ");
        }
        //get requested locale
        Map params = invocation.getInvocationContext().getParameters();
        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);
        }

        //save it in session
        Map session = invocation.getInvocationContext().getSession();
        if (session != null) {
            if (requested_locale != null) {
                Locale locale = (requested_locale instanceof Locale) ?
                        (Locale) requested_locale : LocalizedTextUtil.localeFromString(requested_locale.toString(), null);
                if (log.isDebugEnabled()) {
                    log.debug("store locale=" + locale);
                }

                if (locale != null) {
                    session.put(attributeName, locale);
                }
            }

            //set locale for action
            Object locale = session.get(attributeName);
            if (locale != null && locale instanceof Locale) {
                if (log.isDebugEnabled()) {
                    log.debug("apply locale=" + locale);
                }

                saveLocale(invocation, (Locale)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;
    }

    /**
     * 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);
    }

}