org.springframework.web.servlet.tags.RequestContextAwareTag Maven / Gradle / Ivy
/*
* Copyright 2002-2018 the original author or authors.
*
* 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
*
* https://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 org.springframework.web.servlet.tags;
import jakarta.servlet.jsp.JspException;
import jakarta.servlet.jsp.JspTagException;
import jakarta.servlet.jsp.tagext.TagSupport;
import jakarta.servlet.jsp.tagext.TryCatchFinally;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.servlet.support.JspAwareRequestContext;
import org.springframework.web.servlet.support.RequestContext;
/**
* Superclass for all tags that require a {@link RequestContext}.
*
* The {@code RequestContext} instance provides easy access
* to current state like the
* {@link org.springframework.web.context.WebApplicationContext},
* the {@link java.util.Locale}, the
* {@link org.springframework.ui.context.Theme}, etc.
*
*
Mainly intended for
* {@link org.springframework.web.servlet.DispatcherServlet} requests;
* will use fallbacks when used outside {@code DispatcherServlet}.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see org.springframework.web.servlet.support.RequestContext
* @see org.springframework.web.servlet.DispatcherServlet
*/
@SuppressWarnings("serial")
public abstract class RequestContextAwareTag extends TagSupport implements TryCatchFinally {
/**
* {@link jakarta.servlet.jsp.PageContext} attribute for the
* page-level {@link RequestContext} instance.
*/
public static final String REQUEST_CONTEXT_PAGE_ATTRIBUTE =
"org.springframework.web.servlet.tags.REQUEST_CONTEXT";
/** Logger available to subclasses. */
protected final Log logger = LogFactory.getLog(getClass());
@Nullable
private RequestContext requestContext;
/**
* Create and expose the current RequestContext.
* Delegates to {@link #doStartTagInternal()} for actual work.
* @see #REQUEST_CONTEXT_PAGE_ATTRIBUTE
* @see org.springframework.web.servlet.support.JspAwareRequestContext
*/
@Override
public final int doStartTag() throws JspException {
try {
this.requestContext = (RequestContext) this.pageContext.getAttribute(REQUEST_CONTEXT_PAGE_ATTRIBUTE);
if (this.requestContext == null) {
this.requestContext = new JspAwareRequestContext(this.pageContext);
this.pageContext.setAttribute(REQUEST_CONTEXT_PAGE_ATTRIBUTE, this.requestContext);
}
return doStartTagInternal();
}
catch (JspException | RuntimeException ex) {
logger.error(ex.getMessage(), ex);
throw ex;
}
catch (Exception ex) {
logger.error(ex.getMessage(), ex);
throw new JspTagException(ex.getMessage());
}
}
/**
* Return the current RequestContext.
*/
protected final RequestContext getRequestContext() {
Assert.state(this.requestContext != null, "No current RequestContext");
return this.requestContext;
}
/**
* Called by doStartTag to perform the actual work.
* @return same as TagSupport.doStartTag
* @throws Exception any exception, any checked one other than
* a JspException gets wrapped in a JspException by doStartTag
* @see jakarta.servlet.jsp.tagext.TagSupport#doStartTag
*/
protected abstract int doStartTagInternal() throws Exception;
@Override
public void doCatch(Throwable throwable) throws Throwable {
throw throwable;
}
@Override
public void doFinally() {
this.requestContext = null;
}
}