Spring Framework example source code file (CharacterEncodingFilter.java)

This example Spring Framework source code file (CharacterEncodingFilter.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 - Spring Framework tags/keywords

characterencodingfilter, class, filterchain, http, httpservletrequest, httpservletresponse, io, ioexception, ioexception, onceperrequestfilter, onceperrequestfilter, request, response, servlet, servletexception, servletexception, string, string

The Spring Framework CharacterEncodingFilter.java source code

/*
 * Copyright 2002-2007 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
 *
 *      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 org.springframework.web.filter;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.util.ClassUtils;

/**
 * Servlet 2.3/2.4 Filter that allows one to specify a character encoding for
 * requests. This is useful because current browsers typically do not set a
 * character encoding even if specified in the HTML page or form.
 *
 * <p>This filter can either apply its encoding if the request does not
 * already specify an encoding, or enforce this filter's encoding in any case
 * ("forceEncoding"="true"). In the latter case, the encoding will also be
 * applied as default response encoding on Servlet 2.4+ containers (although
 * this will usually be overridden by a full content type set in the view).
 *
 * @author Juergen Hoeller
 * @since 15.03.2004
 * @see #setEncoding
 * @see #setForceEncoding
 * @see javax.servlet.http.HttpServletRequest#setCharacterEncoding
 * @see javax.servlet.http.HttpServletResponse#setCharacterEncoding
 */
public class CharacterEncodingFilter extends OncePerRequestFilter {

	// Determine whether the Servlet 2.4 HttpServletResponse.setCharacterEncoding(String)
	// method is available, for use in the "doFilterInternal" implementation.
	private final static boolean responseSetCharacterEncodingAvailable = ClassUtils.hasMethod(
			HttpServletResponse.class, "setCharacterEncoding", new Class[] {String.class});


	private String encoding;

	private boolean forceEncoding = false;


	/**
	 * Set the encoding to use for requests. This encoding will be passed into a
	 * {@link javax.servlet.http.HttpServletRequest#setCharacterEncoding} call.
	 * <p>Whether this encoding will override existing request encodings
	 * (and whether it will be applied as default response encoding as well)
	 * depends on the {@link #setForceEncoding "forceEncoding"} flag.
	 */
	public void setEncoding(String encoding) {
		this.encoding = encoding;
	}

	/**
	 * Set whether the configured {@link #setEncoding encoding} of this filter
	 * is supposed to override existing request and response encodings.
	 * <p>Default is "false", i.e. do not modify the encoding if
	 * {@link javax.servlet.http.HttpServletRequest#getCharacterEncoding()}
	 * returns a non-null value. Switch this to "true" to enforce the specified
	 * encoding in any case, applying it as default response encoding as well.
	 * <p>Note that the response encoding will only be set on Servlet 2.4+
	 * containers, since Servlet 2.3 did not provide a facility for setting
	 * a default response encoding.
	 */
	public void setForceEncoding(boolean forceEncoding) {
		this.forceEncoding = forceEncoding;
	}


	protected void doFilterInternal(
			HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {

		if (this.encoding != null && (this.forceEncoding || request.getCharacterEncoding() == null)) {
			request.setCharacterEncoding(this.encoding);
			if (this.forceEncoding && responseSetCharacterEncodingAvailable) {
				response.setCharacterEncoding(this.encoding);
			}
		}
		filterChain.doFilter(request, response);
	}

}