调用Looper.quit()时崩溃

Question

我有一个Android IntentService，它连接到一个web服务，以json格式下载一些作业。然后将这些数据解析并放入SQLite3 DB中。

下面的代码(添加了敏感位)在模拟器上工作，但从未在实际设备上工作。

public class FetchJobsService extends IntentService {
    private final static String LOG_TAG = "FetchJobsService";

    public FetchJobsService() {
        super("FetchJobsService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.i(LOG_TAG, "Fetch Jobs Service Started");

        AsyncHttpClient client = new AsyncHttpClient();

        Map<String, Object> params = new HashMap<String, Object>();
        // Add params to send in the request!
        JSONObject jsonData = new JSONObject(params);

        RequestParams requestParams = new RequestParams();
        requestParams.put(Constants.DATA, jsonData.toString());


        client.post(Constants.FETCH_JOBS, requestParams,
            new AsyncHttpResponseHandler() {
                @Override
                public void onSuccess(int i, Header[] headers, byte[] bytes) {
                    try {
                        JSONObject returnObj = new JSONObject(new String(bytes));
                        Log.i(LOG_TAG, "Success! Jobs downloaded");
                        JSONObject dataObj = returnObj.getJSONObject(Constants.DATA);
                        JSONArray jobs = dataObj.getJSONArray(Constants.JOBS);
                        // Do something with the data downloaded!
                    } catch (JSONException e) {
                        Log.e(LOG_TAG, "Failure! Jobs not successfully downloaded", e);
                    } 
                }

                @Override
                public void onFailure(int statusCode, Header[] headers, byte[] bytes,
                                      Throwable throwable) {
                    Log.i(LOG_TAG, "Failure! Status Code: " + statusCode);
                }
            }
        );

        Log.i(LOG_TAG, "Fetch Jobs Service Finished");
    }
}

它抱怨发帖给一个死线程。在阅读了一段时间之后，我添加了一个Looper，以便在下载和解析数据之前保持IntentService，如下所示：

public class FetchJobsService extends IntentService {
    private final static String LOG_TAG = "FetchJobsService";

    public FetchJobsService() {
        super("FetchJobsService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.i(LOG_TAG, "Fetch Jobs Service Started");

        if (Looper.myLooper() == null) {
            Looper.prepare();
        }

        AsyncHttpClient client = new AsyncHttpClient();

        Map<String, Object> params = new HashMap<String, Object>();
        // Add params to send in the request!
        JSONObject jsonData = new JSONObject(params);

        RequestParams requestParams = new RequestParams();
        requestParams.put(Constants.DATA, jsonData.toString());


        client.post(Constants.FETCH_JOBS, requestParams,
            new AsyncHttpResponseHandler() {
                @Override
                public void onSuccess(int i, Header[] headers, byte[] bytes) {
                    try {
                        JSONObject returnObj = new JSONObject(new String(bytes));
                        Log.i(LOG_TAG, "Success! Jobs downloaded");
                        JSONObject dataObj = returnObj.getJSONObject(Constants.DATA);
                        JSONArray jobs = dataObj.getJSONArray(Constants.JOBS);
                        // Do something with the data downloaded!
                    } catch (JSONException e) {
                        Log.e(LOG_TAG, "Failure! Jobs not successfully downloaded", e);
                    } finally {
                        if (Looper.myLooper() != null) {
                            Looper.myLooper().quit();
                        }
                    }
                }

                @Override
                public void onFailure(int statusCode, Header[] headers, byte[] bytes,
                                      Throwable throwable) {
                    Log.i(LOG_TAG, "Failure! Status Code: " + statusCode);
                    if (Looper.myLooper() != null) {
                        Looper.myLooper().quit();
                    }
                }
            }
        );


        Looper.loop();
        Log.i(LOG_TAG, "Fetch Jobs Service Finished");
    }
}

现在已经成功下载了这些作业，但是对quit()或quitSafely()的调用会导致Fatal signal 11 (SIGSEGV) at 0x0000000c (code=1)崩溃。

如果我删除了对but ()的调用，那么就不会出现崩溃，但是很明显，在应用程序退出之前，服务不会停止并释放资源。

我做错了什么？

Answer 1

IntentService是用来处理自己的生命周期的。您只需重写onHandleIntent回调并执行所需操作--一旦此方法退出，IntentService将关闭自身。

IntentService已经在单独的线程中运行，所以异步地发出请求是没有意义的。您应该在onHandleIntent回调中同步执行网络调用。在这篇文章中有一些例子。

你可以尝试一些这样的方法：

HttpEntity requestEntity = new UrlEncodedFormEntity(params);

//set up post request
final HttpPost post = new HttpPost(url);
post.addHeader(requestEntity.getContentType());
post.setEntity(requestEntity);

//get http client
DefaultHttpClient mHttpClient = new DefaultHttpClient();
final HttpParams httpParams = mHttpClient.getParams();
HttpConnectionParams.setConnectionTimeout(httpParams, TIMEOUT);
HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT);
ConnManagerParams.setTimeout(httpParams, TIMEOUT);

// get response -- this line will block until it is complete -- which is completely fine in an IntentService!
HttpResponse response = getHttpClient().execute(post);

int statusCode = response.getStatusLine().getStatusCode();
String responseEntity = EntityUtils.toString(response.getEntity());

if (statusCode != HttpStatus.SC_OK) {
    // something bad happened, request failed!
} else{
    // response was good, and "responseEntity" can be used for whatever you need
}