无法访问服务器时程序关闭

Question

我是Android和编程领域的新手。 我建立了一个活动，该活动运行一个服务，该服务连接到PHP脚本以从服务器提取一些数据。 问题在于，当程序无法访问服务器时，它会崩溃。 如何防止程序每次无法到达php脚本时崩溃？ 谢谢。

代码的相关部分：

private String getServerData(String returnString) {

      InputStream is = null;

      String result = "";


       try{
               HttpClient httpclient = new DefaultHttpClient();
               HttpPost httppost = new HttpPost(returnString);
               HttpResponse response = httpclient.execute(httppost);
               HttpEntity entity = response.getEntity();
               is = entity.getContent();

       }catch(Exception e){
               Log.e("log_tag", "Error in http connection "+e.toString());
       }

       //convert response to string
       try{
               BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
               StringBuilder sb = new StringBuilder();
               String line = null;
               while ((line = reader.readLine()) != null) {
                       sb.append(line + "\n");
                           }
               is.close();
               result=sb.toString();

           }catch(Exception e){
               Log.e("log_tag", "Error converting result "+e.toString());
       }

       return result; 

   }    

。

08-29 13:10:01.571: ERROR/AndroidRuntime(1116): <p>The requested URL /getAvgScore1.php was not found on this server.</p>
08-29 13:10:01.571: ERROR/AndroidRuntime(1116): <p>Additionally, a 404 Not Found
08-29 13:10:01.571: ERROR/AndroidRuntime(1116): error was encountered while trying to use an ErrorDocument to handle the request.</p>
08-29 13:10:01.571: ERROR/AndroidRuntime(1116): </body></html>
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     at org.apache.harmony.luni.util.FloatingPointParser.initialParse(FloatingPointParser.java:132)
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     at org.apache.harmony.luni.util.FloatingPointParser.parseFloat(FloatingPointParser.java:310)
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     at java.lang.Float.parseFloat(Float.java:327)
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     at java.lang.Float.valueOf(Float.java:368)
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     at iAndroid.RYCQ.rankservice.onCreate(rankservice.java:46)
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     at android.app.ActivityThread.handleCreateService(ActivityThread.java:2465)
08-29 13:10:01.571: ERROR/AndroidRuntime(1116):     ... 10 more
08-29 13:10:01.581: INFO/Process(583): Sending signal. PID: 1116 SIG: 3
08-29 13:10:01.581: INFO/dalvikvm(1116): threadid=7: reacting to signal 3
08-29 13:10:01.591: INFO/dalvikvm(1116): Wrote stack trace to '/data/anr/traces.txt'
08-29 13:10:10.634: WARN/ActivityManager(583): Launch timeout has expired, giving up wake lock!
08-29 13:10:10.634: WARN/ActivityManager(583): Activity idle timeout for HistoryRecord{436eed60 {iAndroid.RYCQ/iAndroid.RYCQ.finalresult}}
08-29 13:10:20.698: WARN/ActivityManager(583): Timeout executing service: ServiceRecord{437c8d88 iAndroid.RYCQ/.rankservice}

Answer 1

连接到服务器失败时，可能只需要捕获引发的任何异常即可。 但是，您需要发布当前正在使用的代码。 无法看到您所做的事情，我们只能随机猜测会解决什么问题。

Answer 2

    public static InputStream fetch(String urlString) throws MalformedURLException, IOException {
    HttpParams httpParameters = new BasicHttpParams();

    int timeoutConnection = 3000;
    HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);

    int timeoutSocket = 5000;
    HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);

    DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
    HttpGet request = new HttpGet(urlString);
    HttpResponse response = httpClient.execute(request);
    return response.getEntity().getContent();
}

您必须放置timeoutConnection和timeoutSocket值，以使设备不会永远等待响应。 有关字段的更多信息可在此处访问。

Answer 3

如果在第一个try块中引发了Exception，则可以在null InputStream上实例化BufferedReader 。 仅具有一个try/catch块，或在第一个catch正确退出该方法。