過濾器

         今天我們來說一下用以前多的老問題post與get方法解決中文亂碼問題與頁面緩存問題，不過今天我們用到了個新的知識-----過濾器。

Post中文亂碼問題

/////////////////////////filter層////////////////////////////////

package cn.class3g.web.filter;
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 LuanMaFilter implements Filter{
	private String bianma = null;
	public void init(FilterConfig filterConfig) throws ServletException {
		bianma = filterConfig.getInitParameter("bianma");
	}
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		request.setCharacterEncoding(bianma);	
		response.setContentType("text/html;charset="+bianma);
		chain.doFilter(request, response);
	}
	public void destroy() {
	}
}

 

/////////////////////////dervlet層////////////////////////////////

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String city = request.getParameter("city");
		PrintWriter out = response.getWriter();
		out.write(city);
	}

 

//////////////////web.xml/////////////////////

<filter>
  	<filter-name>LuanMaFilter</filter-name>
  	<filter-class>cn.class3g.web.filter.LuanMaFilter</filter-class>
  	<init-param>
  		<param-name>bianma</param-name>
  		<param-value>utf-8</param-value>
  	</init-param>
  </filter>
  <filter-mapping>
  	<filter-name>LuanMaFilter</filter-name>
  	<url-pattern>*</url-pattern>
  </filter-mapping>

 

Get中文亂碼問題

String city1 = request.getParameter("city1");
		PrintWriter out = response.getWriter();
		out.write(new String(city1.getBytes("ISO-8859-1"), "UTF-8"));

 

頁面緩存問題

package cn.class3g.web.filter;

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.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class NoCacheFilter implements Filter{

	public void init(FilterConfig filterConfig) throws ServletException {
		// TODO Auto-generated method stub
		
	}
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {
		// TODO Auto-generated method stub
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response =  (HttpServletResponse) res;
		response.setDateHeader("expires",-1);
		response.setHeader("Cache-Control","no-cache");
		response.setHeader("Pragma","no-cache");		
		chain.doFilter(request, response);
	}
	public void destroy() {
		// TODO Auto-generated method stub	
	}
}