如何处理的Java / Android的网络连接速度慢 [英] How to handle slow network connection in Java/Android
问题描述
我有一个使用很多很多电话到MySQL数据库的应用程序;它这里面的的AsyncTask 。下面是一个可能是什么样子的样品
I have an app that uses many, many calls to a MySQL database; it does this inside an AsyncTask. Below is a sample of what one may look like.
我的主要问题是这样的;有时，主机（Godaddy的，唉）决定失速的连接，我的 progressDialog 负荷，负荷和负载更多一些，直到有一个强制关闭和应用程序崩溃。特别是，如果用户试图打断它（大多数我都不过设置为不可撤销，）。
My main question is this; sometimes, the host (Godaddy, ugh) decides to stall a connection and my progressDialog loads, and loads, and loads some more, until there is a force close and the app crashes. Especially if the user tries to interrupt it (most I have set to non-cancelable, however).
有没有更好的方法来处理这比我在下面？我这样做的尝试 / 抓，但不知道如何使用我的优势。
Is there a better way to handle this than I am below? I am doing it in a try/catch, but not sure how to use that to my advantage.
class Task extends AsyncTask<String, String, Void> {
private ProgressDialog progressDialog = new ProgressDialog(
MasterCat.this);
InputStream is = null;
String result = "";
protected void onPreExecute() {
progressDialog.setMessage("Loading...");
progressDialog.show();
progressDialog.setCancelable(false);
}
@Override
protected Void doInBackground(String... params) {
String url_select = "http://www.---.com/---/master.php";
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url_select);
ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
try {
httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// read content
is = httpEntity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
try {
BufferedReader br = new BufferedReader(
new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
// TODO: handle exception
Log.e("log_tag", "Error converting result " + e.toString());
}
return null;
}
protected void onPostExecute(Void v) {
String cat;
try {
jArray = new JSONArray(result);
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
json_data = jArray.getJSONObject(i);
cat = json_data.getString("category");
cats.add(cat);
}
} catch (JSONException e1) {
Toast.makeText(getBaseContext(), "No Categories Found",
Toast.LENGTH_LONG).show();
} catch (ParseException e1) {
e1.printStackTrace();
}
ListView listView = getListView();
listView.setTextFilterEnabled(true);
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> arg0, View arg1,
int arg2, long id) {
Intent i = new Intent(getApplicationContext(), Items.class);
i.putExtra("category", cats.get(arg2));
startActivity(i);
}
});
progressDialog.dismiss();
MasterCatAdapter adapter = new MasterCatAdapter(MasterCat.this,
cats);
setListAdapter(adapter);
}
}
编辑：现在我假定部队密切是因为穷人的连接;但我会尽量让alogcat的时候我可以重新创建它。
Now I AM assuming the force close is because of the poor connection; but I will try to get alogcat up when I can recreate it.
EDIT2：这里是LogCat中：
here is LogCat:
08-13 14:57:00.580: E/WindowManager(2262): Activity com.---.---.MyFragmentActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@42b02cd0 that was originally added here
08-13 14:57:00.580: E/WindowManager(2262): android.view.WindowLeaked: Activity com.---.---.MyFragmentActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@42b02cd0 that was originally added here
08-13 14:57:00.580: E/WindowManager(2262): at android.view.ViewRootImpl.<init>(ViewRootImpl.java:374)
08-13 14:57:00.580: E/WindowManager(2262): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:292)
08-13 14:57:00.580: E/WindowManager(2262): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:224)
08-13 14:57:00.580: E/WindowManager(2262): at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:149)
08-13 14:57:00.580: E/WindowManager(2262): at android.view.Window$LocalWindowManager.addView(Window.java:547)
08-13 14:57:00.580: E/WindowManager(2262): at android.app.Dialog.show(Dialog.java:277)
08-13 14:57:00.580: E/WindowManager(2262): at com.---.---.MyFragmentActivity$RateFragment$RatingTask.onPreExecute(MyFragmentActivity.java:374)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.AsyncTask.execute(AsyncTask.java:534)
08-13 14:57:00.580: E/WindowManager(2262): at com.---.---.MyFragmentActivity$RateFragment$insertTask.onPostExecute(MyFragmentActivity.java:520)
08-13 14:57:00.580: E/WindowManager(2262): at com.---.---.MyFragmentActivity$RateFragment$insertTask.onPostExecute(MyFragmentActivity.java:1)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.AsyncTask.finish(AsyncTask.java:631)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.AsyncTask.access$600(AsyncTask.java:177)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.Handler.dispatchMessage(Handler.java:99)
08-13 14:57:00.580: E/WindowManager(2262): at android.os.Looper.loop(Looper.java:137)
08-13 14:57:00.580: E/WindowManager(2262): at android.app.ActivityThread.main(ActivityThread.java:4745)
08-13 14:57:00.580: E/WindowManager(2262): at java.lang.reflect.Method.invokeNative(Native Method)
08-13 14:57:00.580: E/WindowManager(2262): at java.lang.reflect.Method.invoke(Method.java:511)
08-13 14:57:00.580: E/WindowManager(2262): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-13 14:57:00.580: E/WindowManager(2262): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-13 14:57:00.580: E/WindowManager(2262): at dalvik.system.NativeStart.main(Native Method)
08-13 14:57:00.588: D/AndroidRuntime(2262): Shutting down VM
08-13 14:57:00.588: W/dalvikvm(2262): threadid=1: thread exiting with uncaught exception (group=0x4200b300)
08-13 14:57:00.596: E/AndroidRuntime(2262): FATAL EXCEPTION: main
08-13 14:57:00.596: E/AndroidRuntime(2262): java.lang.NullPointerException
08-13 14:57:00.596: E/AndroidRuntime(2262): at com.---.---.MyFragmentActivity$RateFragment$RatingTask.onPostExecute(MyFragmentActivity.java:461)
08-13 14:57:00.596: E/AndroidRuntime(2262): at com.---.---.MyFragmentActivity$RateFragment$RatingTask.onPostExecute(MyFragmentActivity.java:1)
08-13 14:57:00.596: E/AndroidRuntime(2262): at android.os.AsyncTask.finish(AsyncTask.java:631)
08-13 14:57:00.596: E/AndroidRuntime(2262): at android.os.AsyncTask.access$600(AsyncTask.java:177)
08-13 14:57:00.596: E/AndroidRuntime(2262): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
08-13 14:57:00.596: E/AndroidRuntime(2262): at android.os.Handler.dispatchMessage(Handler.java:99)
08-13 14:57:00.596: E/AndroidRuntime(2262): at android.os.Looper.loop(Looper.java:137)
08-13 14:57:00.596: E/AndroidRuntime(2262): at android.app.ActivityThread.main(ActivityThread.java:4745)
08-13 14:57:00.596: E/AndroidRuntime(2262): at java.lang.reflect.Method.invokeNative(Native Method)
08-13 14:57:00.596: E/AndroidRuntime(2262): at java.lang.reflect.Method.invoke(Method.java:511)
08-13 14:57:00.596: E/AndroidRuntime(2262): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-13 14:57:00.596: E/AndroidRuntime(2262): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-13 14:57:00.596: E/AndroidRuntime(2262): at dalvik.system.NativeStart.main(Native Method)
编辑：这是任务就是在不同的活动，但在LogCat中被引用的：
Here is the Task that is in a different activity but being referenced in LogCat:
class RatingTask extends AsyncTask<String, String, Void> {
private ProgressDialog progressDialog = new ProgressDialog(
getActivity());
InputStream is = null;
String result = "";
protected void onPreExecute() {
progressDialog.setMessage("Loading...");
progressDialog.show();
progressDialog.setOnCancelListener(new OnCancelListener() {
public void onCancel(DialogInterface dialog) {
RatingTask.this.cancel(true);
}
});
}
@Override
protected Void doInBackground(String... params) {
String url_select = "http://www.---.com/---/get_ratings.php";
ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
param.add(new BasicNameValuePair("item", Item));
param.add(new BasicNameValuePair("category", Category));
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url_select);
try {
httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// read content
is = httpEntity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
try {
BufferedReader br = new BufferedReader(
new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
return null;
}
protected void onPostExecute(Void v) {
String starTotal = null, starAvg = null;
try {
JSONArray jArray = new JSONArray(result);
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
json_data = jArray.getJSONObject(i);
starTotal = json_data.getString("TotalRating");
starAvg = json_data.getString("AverageRating");
}
} catch (JSONException e1) {
Log.e("log_tag",
"Error in http connection " + e1.toString());
Toast.makeText(getActivity(), "JSONexception",
Toast.LENGTH_LONG).show();
} catch (ParseException e1) {
e1.printStackTrace();
}
int total = 0;
if (starTotal != null) {
total = Integer.parseInt(starTotal);
} else {
starTotal = "0";
}
if (total > 0) {
total = Integer.parseInt(starTotal);
} else {
total = 0;
}
StarTotal = (TextView) getActivity().findViewById(
R.id.tvStarTotal);
StarTotal.setText("(" + String.valueOf(total) + (")"));
float avg = 0.f;
try {
avg = Float.parseFloat(starAvg);
} catch (NumberFormatException e) {
avg = 0;
}
DecimalFormat myFormat = new DecimalFormat("0.00");
StarNumbers = (TextView) getActivity().findViewById(
R.id.tvStarNumber);
StarNumbers.setText(myFormat.format(avg));
ratingsBarTwo.setRating(Float.valueOf(avg));
progressDialog.dismiss();
}
}
推荐答案
开始与检查是否有一个可用的连接，并通知用户如果不存在
Begin with checking if there is a connection available, and notify the user if there isn't.
特别是如果用户试图打断它（大多数我都不过设置为不可撤销，）。
Especially if the user tries to interrupt it (most I have set to non-cancelable, however).
我会重新考虑这一决定。就个人而言，我不喜欢非中断性流程。我的建议是，你从什么@CommonsWare表明在评论这里下去。不久，有检查数据是否无效，或者你自己的检查，看看你的数据是空的布尔变量。如果是这样，不要执行基于此数据的任何命令，你不会有任何力量关闭与此相关的。
I would reconsider that decision. Personally, I don't like non-interruptible processes. My suggestion is that you go on from what @CommonsWare suggests in the comments here. Shortly, have a boolean variable that checks whether the data is invalid or your own check to see if your data is null. If it is, don't execute any commands based from this data and you won't have any force closes related to this.
有没有更好的方法来处理这比我在下面？
Is there a better way to handle this than I am below?
除了上面什么说的，我建议你添加一些HTTP参数到你的HTTP客户端。例如：
Besides from what is stated above, I'd recommend adding some HTTP parameters to your http client. For example:
final int CONN_WAIT_TIME = 3000;
final int CONN_DATA_WAIT_TIME = 2000;
HttpParams httpParams = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParams, CONN_WAIT_TIME);
HttpConnectionParams.setSoTimeout(httpParams, CONN_DATA_WAIT_TIME);
DefaultHttpClient postClient = new DefaultHttpClient(httpParams);
// Go on...
如果您的HTTP客户端超过你把在各自领域的时候，它会简单地给你一个<一个href="http://developer.android.com/reference/org/apache/http/conn/ConnectTimeoutException.html"><$c$c>ConnectTimeoutException.现在你知道不够的，如果数据是有效的 onPostExecute（）来考虑是否应该继续使用与否。
If your http client exceeds the time you put in their respective fields, it will simply give you a ConnectTimeoutException. Now you know enough to consider if the data is valid in onPostExecute() and whether you should go on using it or not.
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