字符过滤器+在web.xml中的配置

import javax.servlet.*;
import java.io.IOException;

/**
* 字符过滤器
*
* @author 大有软件
*/
public class SetCharacterEncodingFilter implements Filter {

protected String encoding = "GBK";

protected FilterConfig filterConfig = null;

protected boolean ignore = true;

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;
}

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);
}

}
// Pass control on to the next filter
chain.doFilter(request, response);
}

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

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

注意问题：粗斜体的参数部分必须和过滤器中的属性要一样，否则过滤器可能不起作用。

<!-- 字符过滤器 -->
<filter>
<filter-name>encodeFilter</filter-name>
<filter-class>
com.dayou.util.SetCharacterEncodingFilter
</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>GBK</param-value>
</init-param>
<init-param>
<param-name>ignore</param-name>
<param-value>true</param-value>
</init-param>
</filter>

<filter-mapping>
<filter-name>encodeFilter</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>encodeFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>

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