过滤器

过滤器的两种写法：

《一》
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;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;
public class EnCodingFilter extends HttpServlet implements Filter {
 public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
// HttpServletRequest httpRequest = (HttpServletRequest) request;// HttpServletResponse httpResponse = (HttpServletResponse) response;
request.setCharacterEncoding("GBK");filterChain.doFilter(request, response);
}
public void init(FilterConfig filterConfig) throws ServletException {}
}

web.xml配置

<filter><filter-name>EnCodingFilter</filter-name><filter-class>gov.szsf.ccms.common.EnCodingFilter</filter-class></filter>

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

第二种写法

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

 

public class EncodingFilter implements Filter {

    private FilterConfig filterConfig = null;
    private String encoding = null;

     @Override
    public void destroy() {
         filterConfig = null;
         encoding = null;
     }

     @Override
    public void doFilter(ServletRequest request, ServletResponse response,
             FilterChain filterChain) throws IOException, ServletException {
        if (request.getCharacterEncoding() == null) {
            if (encoding != null) {
                 request.setCharacterEncoding(encoding);
             }
             filterChain.doFilter(request, response);
         }
     }

     @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
     }
}

 

web.xml中加入

  <filter>
      <filter-name>EncodingFilter</filter-name>
      <filter-class>EncodingFilter</filter-class>
      <init-param>
          <param-name>encoding</param-name>
          <param-value>UTF-8</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>EncodingFilter</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>