Android上的HTTP请求不起作用

Question

我到处都搜索了，但找不到答案，我怎么能发出HTTP请求？我尝试了几种可能性，但都不起作用。我总是出错。

InputStream is = null;
// Only display the first 500 characters of the retrieved
// web page content.
int len = 500;

try {
URL url = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int response = conn.getResponseCode();
Log.d("Debug:", "The response is: " + response);
is = conn.getInputStream();

// Convert the InputStream into a string
String contentAsString = readIt(is, len);
return contentAsString;

// Makes sure that the InputStream is closed after the app is
// finished using it.
}
catch(Exception ex)
{
    Log.v("Message: ", ex.getMessage());
    return "Helemaal niks!";
}
finally {
    if (is != null) {
        is.close();
    }
}

02-27 17:52:58.611 13571-13571/com.example.app E/AndroidRuntime﹕ 致命异常：主java.lang.IllegalStateException:无法在android.view.view$1.onClick（view.java:3838）在android.view.view.performClick（view.java:4475）在android.view.view$performClick.run（view.java:18786）在android.os.Handler.handleCallback（Handler.java:730）在android.os.Handler.dispatchMessage上执行活动方法android.app.ActivityThread.main（ActivityThread.java:5419）中的android.os.Looper.loop（Looper.java:137）中的Handler.java:92；java.lang.reflect.Method.invokenactive（Native Method）中的java.lang.reflect.Method.invoke（Method.java:525）中的com.android.internal.os.zyoteinit$MethodAndArgsCaller.run（zyoteinit.java:1187）位于com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1003），位于dalvik.system.NativeStart.main（本机方法）

Answer 1

如果只想发出HTTP get请求，可以使用此代码代替代码。

try{
    String result = null;
    HttpClient httpClient = new DefaultHttpClient();
    String myUrl = "your url";
    HttpContext localContext = new BasicHttpContext();
    HttpGet httpGet = new HttpGet(myUrl);
    HttpResponse response = httpClient.execute(httpGet, localContext);

    BufferedReader reader = new BufferedReader(new InputStreamReader(
            response.getEntity().getContent()));

    String line = null;
    while ((line = reader.readLine()) != null) {
        result += line + "\n";
    }
    return result;
}catch(Exception ex)
{
    Log.v("Message: ", ex.getMessage());
    return "Helemaal niks!";
}

Answer 2

所有的webservice调用等都应该在AsyncWork中完成。

这有助于它在不使应用等待的情况下执行。

下面是一个示例代码，可以帮助您了解如何进行网络电话。

try {


        HttpClient httpclient = new DefaultHttpClient();

        HttpParams httpParameters = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParameters, 2000);
        HttpConnectionParams.setSoTimeout(httpParameters, 2000);
        httpclient = new DefaultHttpClient(httpParameters);

        HttpGet request = new HttpGet(Constants.CHECK_UPDATE_URL);

        String responseString = null;

        HttpResponse response = httpclient.execute(request);
        StatusLine statusLine = response.getStatusLine();

        if (statusLine.getStatusCode() == HttpStatus.SC_OK) {

            // Logging Server Responded

            LogActions.systemActions("Server Responded");

            ByteArrayOutputStream out = new ByteArrayOutputStream();
            response.getEntity().writeTo(out);
            out.close();


                            //do your tasks here

        }

    } catch (Exception e) {

        Log.e("Exception", "An impossible exception", e);
    }