https://github.com/spring-projects/spring-framework: Spring Web (Spring IO)
  • Juergen Hoeller 
/*
 * 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.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.lang.Nullable;
import org.springframework.util.Assert;


Servlet 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.

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 (although this will usually be overridden
by a full content type set in the view).

Author:Juergen Hoeller
See Also:
Since:15.03.2004
/**
 * Servlet 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 (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 {

	@Nullable
	private String encoding;

	private boolean forceRequestEncoding = false;

	private boolean forceResponseEncoding = false;


	
Create a default CharacterEncodingFilter, with the encoding to be set via setEncoding. 
See Also:
/**
	 * Create a default {@code CharacterEncodingFilter},
	 * with the encoding to be set via {@link #setEncoding}.
	 * @see #setEncoding
	 */
	public CharacterEncodingFilter() {
	}

	
Create a CharacterEncodingFilter for the given encoding. 
Params:
  • encoding – the encoding to apply
See Also:
Since:4.2.3
/**
	 * Create a {@code CharacterEncodingFilter} for the given encoding.
	 * @param encoding the encoding to apply
	 * @since 4.2.3
	 * @see #setEncoding
	 */
	public CharacterEncodingFilter(String encoding) {
		this(encoding, false);
	}

	
Create a CharacterEncodingFilter for the given encoding. 
Params:
  • encoding – the encoding to apply
  • forceEncoding – whether the specified encoding is supposed to
override existing request and response encodings
See Also:
Since:4.2.3
/**
	 * Create a {@code CharacterEncodingFilter} for the given encoding.
	 * @param encoding the encoding to apply
	 * @param forceEncoding whether the specified encoding is supposed to
	 * override existing request and response encodings
	 * @since 4.2.3
	 * @see #setEncoding
	 * @see #setForceEncoding
	 */
	public CharacterEncodingFilter(String encoding, boolean forceEncoding) {
		this(encoding, forceEncoding, forceEncoding);
	}

	
Create a CharacterEncodingFilter for the given encoding. 
Params:
  • encoding – the encoding to apply
  • forceRequestEncoding – whether the specified encoding is supposed to
override existing request encodings
  • forceResponseEncoding – whether the specified encoding is supposed to
override existing response encodings
See Also:
Since:4.3
/**
	 * Create a {@code CharacterEncodingFilter} for the given encoding.
	 * @param encoding the encoding to apply
	 * @param forceRequestEncoding whether the specified encoding is supposed to
	 * override existing request encodings
	 * @param forceResponseEncoding whether the specified encoding is supposed to
	 * override existing response encodings
	 * @since 4.3
	 * @see #setEncoding
	 * @see #setForceRequestEncoding(boolean)
	 * @see #setForceResponseEncoding(boolean)
	 */
	public CharacterEncodingFilter(String encoding, boolean forceRequestEncoding, boolean forceResponseEncoding) {
		Assert.hasLength(encoding, "Encoding must not be empty");
		this.encoding = encoding;
		this.forceRequestEncoding = forceRequestEncoding;
		this.forceResponseEncoding = forceResponseEncoding;
	}


	
Set the encoding to use for requests. This encoding will be passed into a setCharacterEncoding.setCharacterEncoding call. 
Whether this encoding will override existing request encodings (and whether it will be applied as default response encoding as well) depends on the "forceEncoding" flag. 
/**
	 * 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(@Nullable String encoding) {
		this.encoding = encoding;
	}

	
Return the configured encoding for requests and/or responses.

Since:4.3
/**
	 * Return the configured encoding for requests and/or responses.
	 * @since 4.3
	 */
	@Nullable
	public String getEncoding() {
		return this.encoding;
	}

	
Set whether the configured encoding of this filter is supposed to override existing request and response encodings. 
Default is "false", i.e. do not modify the encoding if getCharacterEncoding.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. 
This is the equivalent to setting both setForceRequestEncoding(boolean) and setForceResponseEncoding(boolean). 
See Also:
/**
	 * 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>This is the equivalent to setting both {@link #setForceRequestEncoding(boolean)}
	 * and {@link #setForceResponseEncoding(boolean)}.
	 * @see #setForceRequestEncoding(boolean)
	 * @see #setForceResponseEncoding(boolean)
	 */
	public void setForceEncoding(boolean forceEncoding) {
		this.forceRequestEncoding = forceEncoding;
		this.forceResponseEncoding = forceEncoding;
	}

	
Set whether the configured encoding of this filter is supposed to override existing request encodings. 
Default is "false", i.e. do not modify the encoding if getCharacterEncoding.getCharacterEncoding() returns a non-null value. Switch this to "true" to enforce the specified encoding in any case. 
Since:4.3
/**
	 * Set whether the configured {@link #setEncoding encoding} of this filter
	 * is supposed to override existing request 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.
	 * @since 4.3
	 */
	public void setForceRequestEncoding(boolean forceRequestEncoding) {
		this.forceRequestEncoding = forceRequestEncoding;
	}

	
Return whether the encoding should be forced on requests.

Since:4.3
/**
	 * Return whether the encoding should be forced on requests.
	 * @since 4.3
	 */
	public boolean isForceRequestEncoding() {
		return this.forceRequestEncoding;
	}

	
Set whether the configured encoding of this filter is supposed to override existing response encodings. 
Default is "false", i.e. do not modify the encoding.
Switch this to "true" to enforce the specified encoding
for responses in any case.

Since:4.3
/**
	 * Set whether the configured {@link #setEncoding encoding} of this filter
	 * is supposed to override existing response encodings.
	 * <p>Default is "false", i.e. do not modify the encoding.
	 * Switch this to "true" to enforce the specified encoding
	 * for responses in any case.
	 * @since 4.3
	 */
	public void setForceResponseEncoding(boolean forceResponseEncoding) {
		this.forceResponseEncoding = forceResponseEncoding;
	}

	
Return whether the encoding should be forced on responses.

Since:4.3
/**
	 * Return whether the encoding should be forced on responses.
	 * @since 4.3
	 */
	public boolean isForceResponseEncoding() {
		return this.forceResponseEncoding;
	}


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

		String encoding = getEncoding();
		if (encoding != null) {
			if (isForceRequestEncoding() || request.getCharacterEncoding() == null) {
				request.setCharacterEncoding(encoding);
			}
			if (isForceResponseEncoding()) {
				response.setCharacterEncoding(encoding);
			}
		}
		filterChain.doFilter(request, response);
	}

}