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闽江学院软件学院&魔舟网络
-10 21

解决J2ME中的ConnectionAlreadyOpen现象

Category:J2me View: Author:spridu

 InputStream isStrm = null;

DataInputStream dataIn = null;
byte[] tbt;
try{
conn = (HttpConnection) Connector.open(url,Connector.READ, true);
   //conn.setRequestProperty("X-Online-Host","10.0.0.172");//设置代理10.0.0.172是移动wap网关
   conn.setRequestProperty( "Content-Type", "text/html" );
   conn.setRequestProperty("Accept", "*/*");
   conn.setRequestProperty("Content-Language", "zh-CN");
   conn.setRequestProperty("User-Agent","Profile/MIDP-2.0 Configuration/CLDC-2.0" );
   conn.setRequestProperty("Pragma", "No-cache");
   conn.setRequestProperty("Cache-Control", "no-cache");//在TOMCAT容器中控制缓存,防止出现connection already open
   conn.setRequestProperty("connection", "keep-alive");
   conn.setRequestProperty("accept-charset", "utf-8");
   conn.setRequestProperty("x-up-calling-line-id", "13800000");
   conn.setRequestMethod(HttpConnection.GET);
   tbt = new byte[(int)conn.getLength()];
   
   int resCode = conn.getResponseCode();
System.out.println("response Code =" + resCode);
   if ( resCode == HttpConnection.HTTP_OK){
   isStrm = conn.openInputStream();
   dataIn = new DataInputStream(isStrm);
   dataIn.read(tbt);
   }
}finally{
if(null != conn){
conn.close();
conn = null;
}
if(null != isStrm){
isStrm.close();
isStrm = null;
}
if(null != dataIn){
dataIn.close();
dataIn = null;
}
}
        return new String(tbt);
原因：tomcat的缓存机制,需要在Header信息中设置失效时间或者是有效期,除此之外还要设置本地禁止缓存和Tomcat禁止缓存等，上面的
代码解决了那个问题，我翻阅国外的网站大半天，包括诺基亚论坛都没有正确的提出解决方案，回头想了下头信息的设置变找了下资料。
conn.setHeader("Content-Type", "application/xml");
  HttpParams param = new BasicHttpParams();
  param.setBooleanParameter("UseCaches", false);
  param.setBooleanParameter("DoInput", true);
  param.setBooleanParameter("DoOutput", true);
  param.setBooleanParameter("InstanceFollowRedirects", false);
  conn.setParams(param);
  conn.setHeader("Accept", "*/*");
  conn.setHeader("Pragma", "No-cache");
  conn.setHeader("Cache-Control", "no-cache");
  conn.setHeader("connection", "keep-alive");
  conn.setHeader("accept-charset", "utf-8");
  conn.setHeader("User-Agent", "Mozilla/5.0");
  conn.setHeader("x-up-calling-line-id", "13800000");
上面是常用的HTTP头信息。
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