乱码问题的解决方案(通过设置过滤器来实现)

乱码问题，究其原因，都是所使用的字符集不一样所导致的。解决方法也有很多种。以下介绍的的事通过设置过滤器

来实现的方法

1、EncodingFilter

package com.njupt.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;

public class EncodingFilter implements Filter {

	@Override
	public void destroy() {
		// TODO Auto-generated method stub

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		
		System.out.println("filter起作用啦啦啦啦");
		HttpServletRequest req = (HttpServletRequest)request;
		String method = req.getMethod();
		if("GET".equals(method)){
			EncodingHttpServletRequestWrapper wrapper = new EncodingHttpServletRequestWrapper(req);
			chain.doFilter(wrapper, response);
		}else{
			chain.doFilter(request,response);
		}
		
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub

	}

}

2、EncodingHttpServletRequestWrapper

package com.njupt.filter;

import java.io.UnsupportedEncodingException;

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

public class EncodingHttpServletRequestWrapper extends
		HttpServletRequestWrapper {

	private HttpServletRequest request;
	
	public EncodingHttpServletRequestWrapper(HttpServletRequest request){
		super(request);
		this.request = request;
	}
	@Override
	public String getParameter(String name) {
		String value = request.getParameter(name);
		
		if(value != null){
			String data = null;
			try {
				data = new String(value.getBytes("iso-8859-1"),"utf-8");
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
			return data;
		}
		
		return super.getParameter(name);
	}
}

需要注意的是，写完了Filter，记得要在web.xml中配置上，配置代码如下：

<filter>
     <filter-name>EncodingFilter</filter-name>
     <filter-class>com.njupt.filter.EncodingFilter</filter-class>
  </filter>
  
  <filter-mapping>
     <filter-name>EncodingFilter</filter-name>
     <url-pattern>/*</url-pattern>
  </filter-mapping>

而且，这时候，JSP页面的编码要显式指明是UTF-8，否则，也很可能开始乱码。代码如下：

<%@ page contentType="text/html; charset=utf-8" %>