用过滤器解决Struts中使用汉字乱码的问题

首先写一个过滤器设置request和response的字符集编码

package filters;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
/**
 * <p>Example filter that sets the character encoding to be used in parsing the
 * incoming request, either unconditionally or only if the client did not
 * specify a character encoding.  Configuration of this filter is based on
 * the following initialization parameters:</p>
 * <ul>
 * <li><b>encoding</b> - The character encoding to be configured
 *     for this request, either conditionally or unconditionally based on
 *     the <code>ignore</code> initialization parameter.  This parameter
 *     is required, so there is no default.</li>
 * <li><b>ignore</b> - If set to "true", any character encoding
 *     specified by the client is ignored, and the value returned by the
 *     <code>selectEncoding()</code> method is set.  If set to "false,
 *     <code>selectEncoding()</code> is called <b>only</b> if the
 *     client has not already specified an encoding.  By default, this
 *     parameter is set to "true".</li>
 * </ul>
 *
 * <p>Although this filter can be used unchanged, it is also easy to
 * subclass it and make the <code>selectEncoding()</code> method more
 * intelligent about what encoding to choose, based on characteristics of
 * the incoming request (such as the values of the <code>Accept-Language</code>
 * and <code>User-Agent</code> headers, or a value stashed in the current
 * user's session.</p>
 *
 * @author Craig McClanahan
 * @version $Revision: 267129 $ $Date: 2004-03-18 11:40:35 -0500 (Thu, 18 Mar 2004) $
 */
public class SetCharacterEncodingFilter implements Filter {
    // ----------------------------------------------------- Instance Variables
    /**
     * The default character encoding to set for requests that pass through
     * this filter.
     */
    protected String encoding = null;
    /**
     * The filter configuration object we are associated with.  If this value
     * is null, this filter instance is not currently configured.
     */
    protected FilterConfig filterConfig = null;
    /**
     * Should a character encoding specified by the client be ignored?
     */
    protected boolean ignore = true;
    // --------------------------------------------------------- Public Methods
    /**
     * Take this filter out of service.
     */
    public void destroy() {
        this.encoding = null;
        this.filterConfig = null;
    }
    /**
     * Select and set (if specified) the character encoding to be used to
     * interpret request parameters for this request.
     *
     * @param request The servlet request we are processing
     * @param result The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain)
    throws IOException, ServletException {
        // Conditionally select and set the character encoding to be used
        if (ignore || (request.getCharacterEncoding() == null)) {
            String encoding = selectEncoding(request);
            if (encoding != null)
                request.setCharacterEncoding(encoding);
            	response.setCharacterEncoding(encoding);
        }
        // Pass control on to the next filter
        chain.doFilter(request, response);
    }
    /**
     * Place this filter into service.
     *
     * @param filterConfig The filter configuration object
     */
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        String value = filterConfig.getInitParameter("ignore");
        if (value == null)
            this.ignore = true;
        else if (value.equalsIgnoreCase("true"))
            this.ignore = true;
        else if (value.equalsIgnoreCase("yes"))
            this.ignore = true;
        else
            this.ignore = false;
    }
    // ------------------------------------------------------ Protected Methods
    /**
     * Select an appropriate character encoding to be used, based on the
     * characteristics of the current request and/or filter initialization
     * parameters.  If no character encoding should be set, return
     * <code>null</code>.
     * <p>
     * The default implementation unconditionally returns the value configured
     * by the <b>encoding</b> initialization parameter for this
     * filter.
     *
     * @param request The servlet request we are processing
     */
    protected String selectEncoding(ServletRequest request) {
        return (this.encoding);
    }
}

然后在web.xml中加入

 <!-- 编码转换过滤器  -->
<filter>
 <filter-name>Encoding</filter-name>
 <filter-class>filters.SetCharacterEncodingFilter</filter-class>
 <init-param>
  <param-name>encoding</param-name>
   <param-value>GBK</param-value>
  </init-param>
 </filter>
 
 <!-- 映射过滤器-->
 <filter-mapping>
  <filter-name>Encoding</filter-name>
  <url-pattern>*.jsp</url-pattern>
 </filter-mapping>
 <filter-mapping>
  <filter-name>Encoding</filter-name>
  <url-pattern>*.do</url-pattern>
 </filter-mapping>

问题分析:

Java类中使用的是Unicode编码,而在网页中使用的通常会是其它的编码,网页提交的数据到Java,或Java中的数据输出到网页的时候就会出现乱码

对于JSP可以使用<%@ page pageEncoding="GBK" contentType="text/html; GBK" language="java" %>网页使用的编码,这样服务器会自动进行转换,对于Servlet可以用request . setCharacterEncoding ( encoding ) ;, 然而对于Struts中的Action和FormBean我们却没有办法.而Struts只能用过滤器来转换汉字编码,但是过滤器对Struts,Servlet,JSP都生效,不过JSP中的PageEncoding仍然不能去掉,它还有声明JSP源文件编码的作用.

参考:

SetCharacterEncodingFilter

http://wiki.apache.org/cocoon/SetCharacterEncodingFilter

这个类只有request过滤器,没有response过滤器

转载注明出处:http://blog.csdn.net/smcr_hetao/archive/2010/01/30/5272724.aspx