Question

这是我关于堆栈溢出的第一个问题。通常我可以自己找到答案，但这次我找不到合适的答案。我也是为Android制作应用程序的新手，所以提前抱歉我的noob'nes。

当本地IP地址不可用时，如何在x miliseconds后取消'android java'中的http请求？我正在使用AsyncTask请求一个html页面。该课程的代码如下。

我现在拥有的是onPreExecute（）中定义的定时器，它在X毫秒之后将onCancel（）设置为true。 doInBackground（）打开一个流等，然后将流写入字符串。

问题是当本地ip地址不可用时，url.openStream（）函数会一直运行，直到java.net.ConnectException因为timeOut而启动。我不知道如何使用onCancel（）来中断此命令（如果这是可能的话）。

那么如何中断url.openStream命令呢？或者只是终止AsyncTask线程？

    private class htmlToString extends AsyncTask<Void,Void,Void> {

    public htmlToString asyncObj;

    @Override
    protected void onPreExecute(){
        asyncObj = this;
        new CountDownTimer(connectionTimeout, connectionTimeout) {
            public void onTick(long millisUntilFinished) {}
            public void onFinish() {
                // stop async task if not in progress
                if (asyncObj.getStatus() == AsyncTask.Status.RUNNING) {
                    asyncObj.cancel(true); // <- how can i cancel the doInBackground with this ?
                    Log.i("timer", "...still trying to connect...");
                }
            }
        }.start();
    }

    @Override
    protected Void doInBackground(Void... params) {
        try {
            URL url = new URL(url_string[button_state]);
            final InputStream url_inputstream = url.openStream(); // <- if the local ip adress is unavailable, this command keeps running until ETIMEDOUT kicks in
            InputStreamReader url_inputstreamreader = new InputStreamReader( url_inputstream );
            BufferedReader in = new BufferedReader( url_inputstreamreader );
            String inputLine;
            while ((inputLine = in.readLine()) != null)
                page = page.concat(inputLine);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void params){
        // some code
    }

}

Edit1：这是在Android Studio 1.5.1中完成的

Edit2：我自己解决了。我只是缩短了java设置的时间。我在doInBackground（）中做了这个（代码如下）。这也意味着我可以完全废弃onPreExecute（）中的计时器。

    @Override
    protected Void doInBackground(Void... params) {
        try {
            URL url = new URL(url_string[button_state]);
            URLConnection url_connection = url.openConnection();
            url_connection.setConnectTimeout(connectionTimeout); // timout is set here
            final InputStream url_inputstream = url_connection.getInputStream();
            InputStreamReader url_inputstreamreader = new InputStreamReader( url_inputstream );
            BufferedReader in = new BufferedReader( url_inputstreamreader );
            String inputLine;
            while ((inputLine = in.readLine()) != null)
                page = page.concat(inputLine);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

Answer 1

httpclient.getConnectionManager().shutdown();

Answer 2

您可以参考以下代码取消请求

 httpget.abort();

示例：

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;



public class ClientAbortMethod {

    public final static void main(String[] args) throws Exception {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        try {
            HttpGet httpget = new HttpGet(<URL>);

            System.out.println("Executing request " + httpget.getURI());
            CloseableHttpResponse response = httpclient.execute(httpget);
            try {
                System.out.println("----------------------------------------");
                System.out.println(response.getStatusLine());

                // Call abort on the request object
                httpget.abort();
            } finally {
                response.close();
            }
        } finally {
            httpclient.close();
        }
    }

}

如何取消http请求

2 个答案: