模拟一个网站登录，获得的验证码和其相应的cookie已经完成，但是等提交的时候总是验证码错误 
static HttpClient httpClient_lab = new DefaultHttpClient(); 
//获取验证码和cookie
 public static byte[] getImgAndcookiesByUrl(String url)
 {
 byte[] data=null;
 String html = null;
 HttpGet httpget = new HttpGet(url);//以get方式请求该URL
 try 
 {
 HttpResponse response = httpClient_lab.execute(httpget);//得到responce对象
int resStatu = response.getStatusLine().getStatusCode();//返回码
if (resStatu==HttpStatus.SC_OK)
 { 
 HttpEntity entity = response.getEntity();
 InputStream inStream=entity.getContent();
 //System.out.println(inStream.toString());
 data = readInputStream(inStream); 
 printHexString(data);
 System.out.println(String.valueOf(data.length));
 inStream.close();
 }
 } 
 catch (Exception e) 
 {
 System.out.println("访问【"+url+"】出现异常!");
System.out.println(e.toString());
 e.printStackTrace();
 } 
 try 
 {
 List<Cookie> cookies = ((AbstractHttpClient)httpClient_lab).getCookieStore().getCookies();   
 if (cookies.isEmpty()) 
 {    
             System.out.println("None");    
         } 
 else 
         {    
             for (int i = 0; i < cookies.size(); i++) 
             {  
              html=cookies.get(i).toString();
              System.out.println(html);   
              String[] str_cookie=html.split(":");
              html=str_cookie[3].substring(1,27);
              FileOperate.write(html);
              System.out.println(html);   
             }    
         }  
 } 
 catch (Exception e) 
 {
 System.out.println("获取cookie出现异常!");
System.out.println(e.toString());
 e.printStackTrace();
 }
 return data;
 }

 //提交登录信息
public static String sendRequestFromHttpClient(Map<String, String> params,String cookies) throws Exception  
     {  
 Log.i("Set-Cookie 0000", cookies);
 String html="";
         //需要把参数放到NameValuePair  
         List<NameValuePair> paramPairs = new ArrayList<NameValuePair>(); 
         if(params!=null && !params.isEmpty())  
         {  
             for(Map.Entry<String, String> entry : params.entrySet())  
             {  
                 paramPairs.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));  
             }  
         }  
         UrlEncodedFormEntity entitydata = new UrlEncodedFormEntity(paramPairs, HTTP.UTF_8);  
         HttpPost post = new HttpPost("http://202.200.151.19/reader/redr_verify.php");
         post.getParams().setParameter(ClientPNames.HANDLE_REDIRECTS, false);  
         post.addHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
         post.addHeader("Accept-Encoding","gzip,deflate,sdch");
         post.addHeader("Accept-Language","zh-CN,zh;q=0.8");
         post.addHeader("Cache-Control","max-age=0");
         post.addHeader("Connection","keep-alive");
         //post.addHeader("Content-Length","69");
         post.addHeader("Content-Type","application/x-www-form-urlencoded");
         post.addHeader("Cookie","PHPSESSID="+cookies);
         post.addHeader("Host","202.200.151.19");
         post.addHeader("Origin","http://202.200.151.19");
         post.addHeader("Referer","http://202.200.151.19/reader/login.php");
         post.addHeader("User-Agent","Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.131 Safari/537.36");
         post.setEntity(entitydata); //设置用户信息 
         //执行post请求  
         //HttpClient httpClient = CustomerHttpClient.getHttpClient(); 
         HttpResponse response = httpClient_lab.execute(post);  
         //从状态行中获取状态码，判断响应码是否符合要求  
         log_cookie = response.getFirstHeader("Set-Cookie").getValue();  
         log_cookie=log_cookie.substring(10, 36);
         Log.i("Set-Cookie 9999", log_cookie);
         Log.i("Set-Cookie code",String.valueOf(response.getStatusLine().getStatusCode()));
         if(response.getStatusLine().getStatusCode()==200)  
         {  
          HttpEntity entity = response.getEntity();
 if (entity!=null) 
 {
 html = EntityUtils.toString(entity);//获得html源代码
}
         }  
         return html;  
     }

访问的网站是http://202.200.151.19/reader/login.php
我觉得每次我用httpclient获到的PHPSESSID是变化的，但实际访问时不管怎么刷新或者提交，不管信息对不对PHPSESSID的值都不变