Java tutorial
/* * 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. * * <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 {@code CharacterEncodingFilter}, * with the encoding to be set via {@link #setEncoding}. * @see #setEncoding */ public CharacterEncodingFilter() { } /** * 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 {@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 {@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 * {@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 */ @Nullable public String getEncoding() { return this.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>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 {@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 */ public boolean isForceRequestEncoding() { return this.forceRequestEncoding; } /** * 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 */ 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); } }