使用HttpURLConnection时出现"非法状态异常:已连接"

Question

当我将DoOutput设置为true时,我收到非法状态异常.

public boolean sendLinksToMaster(String ipport, List<String> links){

        boolean sent = false;
        String[] tokens = ipport.split(":");    
        String data = edu.cis555.searchengine.utils.Utils.generateLinks(links);
        HttpURLConnection conn=null;
        try{
            String encodedData = URLEncoder.encode(data, "UTF-8");
        try{

                String ip =tokens[0];
                String port = tokens[1];
                String path = edu.cis555.searchengine.utils.Constants.URL_ADD_LINK;
                System.setProperty("http.keepAlive", "false");
                URL u = new URL("http", ip, Integer.parseInt(port),"/"+path);

                conn = (HttpURLConnection)u.openConnection();
                //ERROR IN THIS LINE
                conn.setDoOutput(true);
                conn.setRequestMethod("POST");
                OutputStream stream = conn.getOutputStream();
                stream.write(encodedData.getBytes());
                stream.close();

                if(conn.getResponseCode() == HttpURLConnection.HTTP_OK)
                    sent=true;

            //  LOG.debug(conn.getResponseCode());
                conn.disconnect();
            }catch(MalformedURLException mfe){
                LOG.debug(mfe.getMessage());
                if(conn!=null){
                    conn.disconnect();
                }
            }catch(IOException ioe){
                LOG.debug(ioe.getMessage());
                if(conn!=null){
                    conn.disconnect();
                }
            }

        }catch(Exception e){
            LOG.debug(e.getMessage());
            if(conn!=null){
                conn.disconnect();
            }
        }
        return sent;

    }

显示的堆栈跟踪是:

java.lang.IllegalStateException: Already connected
at java.net.URLConnection.setDoOutput(Unknown Source)
at edu.upenn.cis455.xpathengine.utils.pool.ThreadPool.sendLinksToMaster(ThreadPool.java:357)
at edu.upenn.cis455.xpathengine.utils.pool.ThreadPool$Worker.processAndAddToQueue(ThreadPool.java:314)
at edu.upenn.cis455.xpathengine.utils.pool.ThreadPool$Worker.run(ThreadPool.java:269)
at java.lang.Thread.run(Unknown Source)

发送请求时,我没有看到任何错误.任何人都可以指出缺少什么或我做错了什么

Answer 1

我遇到了同样的问题并解决了它.就我而言,这是因为我connection.getResponseCode()在NetBeans的调试界面中忘记了一下.希望它可以帮助其他人犯同样的错误.

如果您有任何相对于请求的响应值,如:手表getResponseCode(),getResponseMessage(),getInputStream()甚至只是connect(),你会得到在调试模式下此错误.

所有以前的方法都隐式调用connect()并触发请求.所以当你到达时setDoOutput,连接已经完成.