Java編碼過濾器的編寫

首先，新建一個Filter，命名爲：SetCharacterEncodingFilter

 

代碼如下：

package com.mytest.struts.util;


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;

public class SetCharacterEncodingFilter implements Filter {

    /**
     * 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 void destroy() {
        this.encoding = null;
        this.filterConfig = null;
    }

    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);
        }
        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 String selectEncoding(ServletRequest request) {
        return (this.encoding);
    }

}

 

然後需要在web.xml配置文件中配置如下：

<filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>com.mytest.struts.util.SetCharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>ignore</param-name>
        <param-value>false</param-value>
    </init-param>
  </filter>

  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>