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如何用过滤器过滤HTTP协议和非HTTP协议编码

在编写web时,最苦恼的事情就是乱码了。

一直没怎么考虑过JSP第一句话中

<%@ page language="java" contentType="text/html; charset=GBK"  pageEncoding="GBK"%>
的ContentType和pageEncoding具体是用做什么的,害自己做了过滤器也老是出现问题。

Google下:

contentType ------------指定的是JSP页最终 Browser(客户端)所见到的网页内容的编码.

pageEncoding ------------指定JSP编写时所用的编码
如果害怕忘了在每个jsp都加上这样的编码,或者由于不同环境所需的客户端所见编码的不同。加上过滤器来解决

1.HTTP协议下的过滤:

(1.login.jsp   )用来模拟输入数据登录

<%@ page language="java"  pageEncoding="GBK"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" >
<title>HTTP协议和URL编码</title>
</head>
<body>
<p>这里仅仅POST编码测试</p>
<form action="main.jsp" method="post">
<label>测试HTTP协议</label>
<input type="text" name="infoPost" />
<input type="submit" value=http://www.mamicode.com/"提交"> > 

(2.main.jsp  )用来模拟得到数据

<%@ page language="java"  pageEncoding="GBK"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" >
<title>获取页面传过来的值</title>
</head>
<body>
 获取通过HTTP协议传送过来的值 
<%=request.getParameter("infoPost") %>
<hr>
获取通过URL传送过来的值
<%=request.getParameter("infoGet") %>
</body>
</html>
(3.web.xml)配置

<!-- 编码过滤器 -->
 <filter>
 <filter-name>EncodeFilter</filter-name>
 <filter-class>demo.filter.EncodeFilter</filter-class>
 <init-param>
 <param-name>encoding</param-name>
 <param-value>GBK</param-value>
 </init-param>
 </filter>
 <filter-mapping>
 <filter-name>EncodeFilter</filter-name>
 <url-pattern>/*</url-pattern>
 </filter-mapping>


(4.EncodeFilter.java)过滤器类

package demo.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;

/** 字符编码 */
public class EncodeFilter implements Filter {
	protected String encoding;
	protected FilterConfig filterConfig;

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

	public void destroy() {

		filterConfig = null;
		encoding = null;
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		/*
		 * 处理通过HTTP协议提交的数据
		 */
		HttpServletRequest hrequest = (HttpServletRequest) request;
		HttpServletResponse hresponse = (HttpServletResponse) response;
		// 这里省略前面两段,直接用request..setCharacterEncoding(encoding);效果是一样的,这里为了说明这个是通过HTTP
		// 协议提交
		System.out.println("编码格式" + encoding);
		hrequest.setCharacterEncoding(encoding);
		filterChain.doFilter(request, response);

	}

	/*
	 * 过滤器初始化
	 */
	public void init(FilterConfig filterConfig) throws ServletException {
		this.filterConfig = filterConfig;
		encoding = filterConfig.getInitParameter("encoding");

	}

}

结果:

  

post方式参数存放在请求数据包的消息体中。get方式参数存放在请求数据包的请求行的URI字段中,以?开始以param=value&&parame2=value2的形式附加在URI字段之后。而request.setCharacterEncoding(charset); 只对消息体中的数据起作用,对于URI字段中的参数不起作用。

可以继承扩展HttpServletRequestWrapper 增加过滤功能

添加一个MyEncodeFilter类

package demo.filter;

import java.io.UnsupportedEncodingException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class MyEncodeFilter extends HttpServletRequestWrapper{

	private String encoding="GBK";
	public MyEncodeFilter(HttpServletRequest request) {
		super(request);
		
	}
	public MyEncodeFilter(HttpServletRequest request,String encoding) {
		super(request);
		this.encoding=encoding;
		
	}
	//新增加一个转码方法
	public String encodeName(String en){
		
		try {
			return new String(en.trim().getBytes("ISO-8859-1"),encoding);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			return en;
			
		}
		
	}
	//增强过滤的方法,就是将URI字段中的参数编码(重写)

	public String getParameter(String name) {
		//直接调用父类的getParameter方法获取参数的值
		String value=http://www.mamicode.com/super.getParameter(name);> 

改变后的Filter:

package demo.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;

/** 字符编码 */
public class EncodeFilter  implements Filter {
	protected String encoding;
	protected FilterConfig filterConfig;

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

	public void destroy() {

		filterConfig = null;
		encoding = null;
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		/*
		 * 处理通过HTTP协议提交的数据
		 */
		HttpServletRequest hrequest = (HttpServletRequest) request;
		// 这里省略前面两段,直接用request..setCharacterEncoding(encoding);效果是一样的,这里为了说明这个是通过HTTP
		// 协议提交
		System.out.println("编码格式" + encoding);
		hrequest.setCharacterEncoding(encoding);
		//新增加方法<只要通过url来头中肯定有get>
		if(hrequest.getMethod().equalsIgnoreCase("get")){
			hrequest=new MyEncodeFilter(hrequest,encoding);
			
		}
		 //
		filterChain.doFilter(hrequest, response);

	}

	/*
	 * 过滤器初始化
	 */
	public void init(FilterConfig filterConfig) throws ServletException {
		this.filterConfig = filterConfig;
		encoding = filterConfig.getInitParameter("encoding");

	}

}

解决成功!