在web專案中我們經常會遇到當前臺P頁面和程式碼中使用了不同的字符集進行編碼的時候就會出現表單提交的資料或者上傳/下載中文名稱檔案出現亂碼的問題，這些問題的原因就是因為我們專案中使用的編碼不一樣。為了解決這個問題我們就可以使用CharacterEncodingFilter類，他是Spring框架對字元編碼的處理，基於函式回撥,對所有請求起作用,只在容器初始化時呼叫一次,依賴於servlet容器.具體配置如下：

<filter>
        <filter-name>characterEncodingFilter</filter-name>
        <!--配置轉碼，將編碼都轉為UTF-8-->
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern><!-- 攔截路徑-->
    </filter-mapping>

下面是Spring的原始碼

/*
 * 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;
im
 
port javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
/**
 * 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 {
 
	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;
	}
 
	/**
	 * Shttp://www.cppcns.comet 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;
	}
 
 
	@Override
	protected void doFilterInternal(
			HttpServletRequest request,HttpServletResponse response,FilterChain filterChain)
			throws ServletException,IOException {
 
		if (this.encoding != null && (this.forceEncoding || request.getCharacterEncoding() == null)) {
			request.setCharacterEncodihttp://www.cppcns.comng(this.encoding);
			if (this.forceEncoding) {
				response.setCharacterEncoding(this.encoding);
			}
		}
		filterChain.doFilter(request,response);
	}
 
}
 

從上面的配置和原始碼我們可以發現

在配置字符集過濾器時可設定兩個引數的值，

1. encoding：字符集，即將過濾到的request的字符集設定為encoding指定的值，相當於

request.setCharacterEncoding("")

2. forceEncoding：字面意思是強制字符集，這個引數的值是指定response的字符集是否也設定成encoding所指定的字符集，所以你可以選擇設定為true或false，當值為true時，相當於

request.setCharacterEncoding("");  
response.setCharacterEncoding("");

當值為false時，相當於：

request.setCharacterEncoding("");

到此這篇關於Java CharacterEncodingFilter過濾器的理解和配置案例詳解的文章就介紹到這了,更多相關Java CharacterEncodingFilter過濾器內容請搜尋我們以前的文章或繼續瀏覽下面的相關文章希望大家以後多多支援我們！