通过输出过滤器用out输出一个页面， 如何是乱码

通过输出过滤器用out输出一个页面， 怎么是乱码
PrintWriter   out=response.getWriter();
......
chain.doFilter(request,wrapper);
....
  String   resStr=wrapper.toString();
  resStr=resStr.replaceAll( "null ",   " ");      
  System.out.println(resStr);
  out.println(resStr);


后台输出的都是正常的汉字,可生成在页面却都是乱码,好象response应该设置响应头的，忘记了,请教各位

------解决方案--------------------
response.setContentType( "text/html;charset=gb2312 ");
------解决方案--------------------
response.setContentType( "text/html;charset=GBK ");
楼主想必是忘了这条了。
------解决方案--------------------
最好是加一个字符转换的过滤类，配置如下web.xml
<filter>
<filter-name> Set Character Encoding </filter-name>
<filter-class> common.util.filter.SetCharacterEncodingFilter </filter-class>
<init-param>
<param-name> encoding </param-name>
<param-value> GBK </param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name> Set Character Encoding </filter-name>
<url-pattern> /* </url-pattern>
</filter-mapping>
------解决方案--------------------
类源码如下：
package common.util.filter;

import javax.servlet.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.UnavailableException;

public class SetCharacterEncodingFilter implements Filter {
protected String encoding = null;

protected FilterConfig filterConfig = null;

protected boolean ignore = true;

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

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {

// Conditionally select and set the character encoding to be used
if (ignore || (request.getCharacterEncoding() == null)) {
String encoding = selectEncoding(request);
if (encoding != null)
request.setCharacterEncoding(encoding);
}

// Pass control on to the next filter
chain.doFilter(request, response);
}

public void init(FilterConfig filterConfig) throws ServletException {

this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter( "encoding ");
String value = filterConfig.getInitParameter( "ignore ");
if (value == null)
this.ignore = true;
else if (value.equalsIgnoreCase( "true "))
this.ignore = true;
else if (value.equalsIgnoreCase( "yes "))
this.ignore = true;
else
this.ignore = false;

}

protected String selectEncoding(ServletRequest request) {
return (this.encoding);
}

}