Question

我到处搜索但我找不到答案，我怎样才能发出HTTP请求？我尝试了几种可能性，但没有一种可行。我一直都有错误。

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：FATAL EXCEPTION：main java.lang.IllegalStateException：无法执行活动的方法在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（Handler.java:92）在android.os.Looper.loop（Looper.java:137）在android.app.ActivityThread.main（ActivityThread.java:5419） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:525）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1187）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1003）在dalvik.system.NativeStart.main（本地方法）

Answer 1

如果您只想发出HTTP get请求，则可以使用此代码而不是代码。

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webservice调用等应始终在 AsyncTask 中完成。

这有助于它在不让应用程序等待的情况下执行。

以下示例代码可帮助您了解如何制作网络摄像头。

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);
    }

Android上的HTTP请求无效

2 个答案: