http Client 出现生僻字

        //cookie
        HttpSession session=request.getSession();
        Object cookie=null;
        cookie=session.getAttribute(KEY_COOKIE);  
        
        //设置header
        PostMethod method = new PostMethod(url);  
        if(cookie!=null){
            method.setRequestHeader("Cookie", ""+cookie); 
        }
        
        Enumeration en=request.getHeaderNames();
        while(en.hasMoreElements()){
            String n=(String)en.nextElement();
            String v=request.getHeader(n); 
            method.setRequestHeader(n, v); 
        }  
        method.setRequestHeader("content-length", ""+content.getBytes().length);
        
        System.out.println("[RailUtil]Request:\n" + content + "\n");
        
        //设置内容
        method.setRequestBody(content); 
        method.setRequestHeader("Content-type", "text/xml; charset=GBK");
        
        //Client
        org.apache.commons.httpclient.HttpClient client = new org.apache.commons.httpclient.HttpClient(); 
        client.getParams().setContentCharset("GBK"); 
        //设置超时 5秒
        client.setTimeout(TIMEOUT); 
        
        //发送请求
        try {
            client.executeMethod(method);
        } catch (HttpException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
            throw new Exception("连接超时或信道错误",e1);
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
            throw new Exception("连接超时或信道错误",e1);
        } 
        
        //保存 cookie
        Header newCookieHeader = method.getResponseHeader("Set-Cookie");
        if(newCookieHeader!=null) session.setAttribute(KEY_COOKIE, newCookieHeader.getValue());
 
         //输出返回
        StringBuilder sb_res=new StringBuilder();
        InputStream bis=null;
        try{ 
            bis=method.getResponseBodyAsStream(); 
             
            byte[] bb=new byte[1024];
            int len_res=0;
            while((len_res=bis.read(bb))>0){  
                //bb = new String(bb, "GB2312").getBytes("GBK"); 
                sb_res.append(new String(bb,0,len_res));
            }
                }catch(IOException e){
            throw new Exception("读取返回信息失败",e);
        }finally{
             if(bis!=null)bis.close();
        } 

 

代码如上，应该可以看得明白。现在问题是返回的字符串，我是用xml格式存放信息，其中部分中文字被转换为生僻字，这个是什么原因呢？

问题补充：
to lovewhzlq
如何指定正确的编码呢？返回的字符串可以检测到编码方式么？

[code="java"]
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
import org.apache.commons.httpclient.params.HttpMethodParams;

import java.io.*;

public class HttpClientTutorial {

private static String url = "http://www.apache.org/";

public static void main(String[] args) {
// Create an instance of HttpClient.
HttpClient client = new HttpClient();

// Create a method instance.
GetMethod method = new GetMethod(url);

// Provide custom retry handler is necessary
method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, 
        new DefaultHttpMethodRetryHandler(3, false));

try {
  // Execute the method.
  int statusCode = client.executeMethod(method);

  if (statusCode != HttpStatus.SC_OK) {
    System.err.println("Method failed: " + method.getStatusLine());
  }

  // Read the response body.
  byte[] responseBody = method.getResponseBody();

  // Deal with the response.
  // Use caution: ensure correct character encoding and is not binary data

//这里就可以设置编码得到正确的字符
System.out.println(new String(responseBody,"utf-8"));

} catch (HttpException e) {
  System.err.println("Fatal protocol violation: " + e.getMessage());
  e.printStackTrace();
} catch (IOException e) {
  System.err.println("Fatal transport error: " + e.getMessage());
  e.printStackTrace();
} finally {
  // Release the connection.
  method.releaseConnection();
}  

}
}

[/code]

这个应该是你读取响应字符串时没有指定正确的编码吧