写了一个jsp程序，运行之后中文显示的是乱码．这是怎么回事？？给出代码和运行情况如下：

Question

方法1：<%@ page contentType="text/html; charset=gb2312" language="java">方法2：<meta http-equiv="Content-Type" content="text/html; charset=gb2312">方法3：<%@ page import="java.io.*"%>
<%! String trans(String chi)
{
               String result = null;
               byte temp [];
               try
               {
                       temp=chi.getBytes("iso-8859-1");
                      result = new String(temp);
                }
                catch(UnsupportedEncodingException e)
                {
                        System.out.println (e.toString());
                }
return result;
}
%>
<%
out.println(trans(request.getParameter("name")));
%>方法4：过滤器
package com.cwb;import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;public class EncodingFilter implements Filter
{
    protected FilterConfig filterConfig;
    private String targetEncoding = "gb2312";
    
    public void init(FilterConfig config) throws ServletException
{
        this.filterConfig = config;
        this.targetEncoding = config.getInitParameter("encoding");
    }
    
     public  void doFilter(ServletRequest srequest, ServletResponse  sresponse, FilterChain chain)throws IOException, ServletException
 {
            
HttpServletRequest request = (HttpServletRequest)srequest;
 
request.setCharacterEncoding(targetEncoding);
 
chain.doFilter(srequest,sresponse);  
    }    public void setFilterConfig(final FilterConfig filterConfig)
{
this.filterConfig=filterConfig;
}
    
public void destroy()
{
this.filterConfig=null;
}
}

Answer 1

方法1：<%@ page contentType="text/html; charset=gb2312" language="java">方法2：<meta http-equiv="Content-Type" content="text/html; charset=gb2312">方法3：<%@ page import="java.io.*"%>
<%! String trans(String chi)
{
               String result = null;
               byte temp [];
               try
               {
                       temp=chi.getBytes("iso-8859-1");
                      result = new String(temp);
                }
                catch(UnsupportedEncodingException e)
                {
                        System.out.println (e.toString());
                }
return result;
}
%>
<%
out.println(trans(request.getParameter("name")));
%>方法4：过滤器
package com.cwb;import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;public class EncodingFilter implements Filter
{
    protected FilterConfig filterConfig;
    private String targetEncoding = "gb2312";
    
    public void init(FilterConfig config) throws ServletException
{
        this.filterConfig = config;
        this.targetEncoding = config.getInitParameter("encoding");
    }
    
     public  void doFilter(ServletRequest srequest, ServletResponse  sresponse, FilterChain chain)throws IOException, ServletException
 {
            
HttpServletRequest request = (HttpServletRequest)srequest;
 
request.setCharacterEncoding(targetEncoding);
 
chain.doFilter(srequest,sresponse);  
    }    public void setFilterConfig(final FilterConfig filterConfig)
{
this.filterConfig=filterConfig;
}
    
public void destroy()
{
this.filterConfig=null;
}
}

Answer 2

方法1：<%@ page contentType="text/html; charset=gb2312" language="java">方法2：<meta http-equiv="Content-Type" content="text/html; charset=gb2312">方法3：<%@ page import="java.io.*"%>
<%! String trans(String chi)
{
               String result = null;
               byte temp [];
               try
               {
                       temp=chi.getBytes("iso-8859-1");
                      result = new String(temp);
                }
                catch(UnsupportedEncodingException e)
                {
                        System.out.println (e.toString());
                }
return result;
}
%>
<%
out.println(trans(request.getParameter("name")));
%>方法4：过滤器
package com.cwb;import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;public class EncodingFilter implements Filter
{
    protected FilterConfig filterConfig;
    private String targetEncoding = "gb2312";
    
    public void init(FilterConfig config) throws ServletException
{
        this.filterConfig = config;
        this.targetEncoding = config.getInitParameter("encoding");
    }
    
     public  void doFilter(ServletRequest srequest, ServletResponse  sresponse, FilterChain chain)throws IOException, ServletException
 {
            
HttpServletRequest request = (HttpServletRequest)srequest;
 
request.setCharacterEncoding(targetEncoding);
 
chain.doFilter(srequest,sresponse);  
    }    public void setFilterConfig(final FilterConfig filterConfig)
{
this.filterConfig=filterConfig;
}
    
public void destroy()
{
this.filterConfig=null;
}
}

Answer 3

按照你们说的，我照做了，结果是：那几个参数变量显示有问题了．．
参数名称[age][name][Submit][interest]
姓名（name):????????
年龄（age):??
兴趣(interest):