HttpURLConnection获取网页源码 网址太长不能正确获取数据

我用HttpURLConnection获取网页源码 当网址比较长的时候就无法正确连接到网页是怎么回事？

代码如下：

private String getURLResponse(String urlString){

HttpURLConnection conn = null; //连接对象

InputStream is = null;

String resultData = "";

try {

URL url = new URL(urlString); //URL对象

conn = (HttpURLConnection)url.openConnection(); //使用URL打开一个链接

conn.setDoInput(true); //允许输入流，即允许下载

conn.setDoOutput(true); //允许输出流，即允许上传

conn.setUseCaches(false); //不使用缓冲

conn.setRequestMethod("GET"); //使用get请求

is = conn.getInputStream(); //获取输入流，此时才真正建立链接

InputStreamReader isr = new InputStreamReader(is);

BufferedReader bufferReader = new BufferedReader(isr);

String inputLine = "";

while((inputLine = bufferReader.readLine()) != null){

resultData += inputLine + "\n";

}

    } catch (MalformedURLException e) {  
        // TODO Auto-generated catch block  
        e.printStackTrace();  
    }catch (IOException e) {  
        // TODO Auto-generated catch block  
        e.printStackTrace();  
    }finally{  
        if(is != null){  
            try {  
                is.close();  
            } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            }  
        }  
        if(conn != null){  
            conn.disconnect();  
        }  
    }  

    return resultData;  
}  
    }

conn.setRequestMethod("POST"); 使用POST请求