我创建的应用程序从服务器获取带AsyncTask的JSON。当用户单击按钮应用程序启动新活动并从服务器下载数据并将其显示为ListView中的项目。问题是，当我打开新Activity时，加载时间太长。当按下按钮时，应用程序冻结约一秒或两秒钟，然后再显示黑屏2/3秒。显示该活动后但速度非常慢。每次用户滚动或按下按钮时它都会冻结以显示自定义适配器的更多选项。有没有办法让应用更流畅？下载的Json数据只是简单的JSONArray JSONObjects，其中包含2个字符串值和一个HTML格式。这3个值显示给用户。
自定义适配器类的一部分
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
SuggestionList suggestionList = getItem(position);
int actualPosition = 0;
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.sugestion_list, parent, false);
}
final Button suggestionsButton = (Button) convertView.findViewById(R.id.suggestionsMore);
final TextView suggestionNumber = (TextView) convertView.findViewById(R.id.sugestionNumber);
final TextView suggestionDescription = (TextView) convertView.findViewById(R.id.suggestionDescription);
final ImageView bio = convertView.findViewById(R.id.sugestionBio);
final ImageView block = convertView.findViewById(R.id.sugestionBlock);
final ImageView call = convertView.findViewById(R.id.sugestionCall);
...
final Animation slideUp = AnimationUtils.loadAnimation(getContext(), R.anim.slideup);
final Animation slideDown = AnimationUtils.loadAnimation(getContext(), R.anim.slidedown);
final Handler handler = new Handler();
suggestionsButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (bioSuggestions.getVisibility() == View.GONE) {
bio.setVisibility(View.VISIBLE);
block.setVisibility(View.VISIBLE);
call.setVisibility(View.VISIBLE);
bioSuggestions.startAnimation(slideUp);
blockSuggestions.startAnimation(slideUp);
callSuggestions.startAnimation(slideUp);
} else if (bioSuggestions.getVisibility() == View.VISIBLE) {
bioSuggestions.startAnimation(slideDown);
blockSuggestions.startAnimation(slideDown);
callSuggestions.startAnimation(slideDown);
handler.postDelayed(new Runnable() {
@Override
public void run() {
bio.setVisibility(View.GONE);
block.setVisibility(View.GONE);
call.setVisibility(View.GONE);
}
}, 300);
}
}
});
if (actualPosition != position) {
if (bio.getVisibility() == View.VISIBLE) {
bio.setVisibility(View.GONE);
block.setVisibility(View.GONE);
call.setVisibility(View.GONE);
}
actualPosition = position;
}
JSONObject jsonValSuggestions = new getSugestions().sugestionsDetails(position, "suggestions");
try {
final String name = jsonValSuggestions.getString("client_name");
final String num = jsonValSuggestions.getString("client_number");
final String description = jsonValSuggestions.getString("client_description");
bio.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent suggestionsDetails = new Intent(view.getContext(), SuggestionsDetails.class);
suggestionsDetails.putExtra("client_number", num);
suggestionsDetails.putExtra("client_name", name);
suggestionsDetails.putExtra("client_description", description);
activity.startActivityForResult(suggestionsDetails, position);
}
});
block.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent suggestionBlock = new Intent(view.getContext(), BlockSuggestionsActivity.class);
activity.startActivity(suggestionBlock);
}
});
call.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent suggestionCall = new Intent(view.getContext(), CallSuggestionActivity.class);
suggestionCall.putExtra("client_number", num);
suggestionCall.putExtra("client_name", name);
activity.startActivity(suggestionCall);
}
});
} catch (Exception e) {
e.printStackTrace();
}
try {
if (suggestionList.suggestionName.equals("null") || suggestionList.suggestionName.equals("")) {
suggestionNumber.setText(suggestionList.suggestionNumber);
} else {
suggestionNumber.setText(suggestionList.suggestionName);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
suggestionDescription.setText(Html.fromHtml(suggestionList.suggestionDescription, Html.FROM_HTML_MODE_LEGACY));
} else {
suggestionDescription.setText(Html.fromHtml(suggestionList.suggestionDescription));
}
} catch (Exception e) {
Log.i("exception", e.getMessage());
}
return convertView;
}
AsyncTask类的一部分
public static final String REQUEST_METHOD = "GET";
public static final int READ_TIMEOUT = 15000;
public static final int CONNECTION_TIMEOUT = 15000;
@Override
protected String doInBackground(String... params) {
String clientUrl = params[0];
String result;
String inputLine;
JSONObject obj;
String data;
String message;
try {
URL myUrl = new URL(clientUrl);
HttpURLConnection connection = (HttpURLConnection) myUrl.openConnection();
connection.setRequestMethod(REQUEST_METHOD);
connection.setReadTimeout(READ_TIMEOUT);
connection.setConnectTimeout(CONNECTION_TIMEOUT);
connection.connect();
InputStreamReader streamReader = new InputStreamReader(connection.getInputStream());
BufferedReader reader = new BufferedReader(streamReader);
StringBuilder stringBuilder = new StringBuilder();
while ((inputLine = reader.readLine()) != null) {
stringBuilder.append(inputLine);
}
reader.close();
streamReader.close();
result = stringBuilder.toString();
} catch (IOException e) {
e.printStackTrace();
result = null;
}
return result;
}
public String[] getSuggestionsList() {
String[] suggestionList = new String[5];
String result;
String status;
JSONObject listObj;
String suggestionsData;
JSONObject suggestionsDataObj;
JSONArray suggestionsDataArr;
String ClientsSugestionsUrl = "https://example.com/token=" + authToken;
getApiClientSugestions getSugestionsFromApi = new getApiClientSugestions();
try {
result = getSugestionsFromApi.execute(ClientsSugestionsUrl).get();
try {
listObj = new JSONObject(result);
status = listObj.getString("result");
suggestionsData = listObj.getString("suggestions");
suggestionsDataArr = new JSONArray(suggestionsData);
} catch (Exception e) {
e.printStackTrace();
suggestionsDataArr = null;
status = null;
}
suggestionList[3] = status;
suggestionList[4] = suggestionsDataArr.toString();
} catch (Exception e) {
e.printStackTrace();
}
return suggestionList;
}
活动
public class CallsSuggestionsActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calls_suggestions);
Slidr.attach(this);
getSupportActionBar().setTitle("Skontaktuj się");
}
@Override
protected void onResume() {
super.onResume();
CallsSuggestionList();
}
public void CallsSuggestionList() {
final ListView suggestionList = findViewById(R.id.sugestionList);
final ArrayList<SuggestionList> suggestionArray = new ArrayList<SuggestionList>();
SuggestionListAdapter suggestionListAdapter = new SuggestionListAdapter(getContext(), suggestionArray, this);
String[] suggestionListArray = new getSugestions().getSuggestionsList();
String suggStat = suggestionListArray[3];
String arrayList = suggestionListArray[4];
String clientName;
String clientNumber;
String clientDescription;
try {
JSONArray jsonArray = new JSONArray(arrayList);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject explrObject = jsonArray.getJSONObject(i);
clientName = explrObject.getString("client_name");
clientNumber = explrObject.getString("client_number");
clientDescription = explrObject.getString("client_description");
if (suggStat.equals("true")) {
SuggestionList suggestionList1 = new SuggestionList(clientName, clientDescription, clientNumber);
suggestionListAdapter.addAll(suggestionList1);
suggestionListAdapter.notifyDataSetChanged();
suggestionList.setAdapter(suggestionListAdapter);
}
}
} catch (Exception e) {
Log.i("exception", e.getMessage());
e.printStackTrace();
clientName = null;
clientDescription = null;
clientNumber = null;
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
SuggestionList
public class SuggestionList {
public String suggestionNumber;
public String suggestionDescription;
public String suggestionCallType;
public String suggestionName;
public SuggestionList(
// String suggestionCallType,
String suggestionName, String suggestionDescription, String suggestionNumber) {
this.suggestionNumber = suggestionNumber;
// this.suggestionCallType = suggestionCallType;
this.suggestionName = suggestionName;
this.suggestionDescription = suggestionDescription;
}
}
Adapter是自定义的，并向用户显示自定义视图。我使用类似的自定义适配器来显示手机上的sqlite内容，并且应用程序不是那么慢。但是当我打开这个活动时，它会大幅减速。另外我注意到当我按下后退按钮时需要很长时间才能回到上一个屏幕。
答案 0 :(得分：1)
问题出在getSuggestionsList函数中。在此函数中，您正在调用getSugestionsFromApi.execute(ClientsSugestionsUrl).get();，这会使您的代码再次同步。我的意思是你的代码正在等待执行这段代码。
一种方式（不是正确的方式，但简单方法）：您可以在新线程中调用新的getSugestions().getSuggestionsList();。
第二种方式，在没有getSugestionsFromApi.execute(ClientsSugestionsUrl)功能的情况下调用get()。但是要获得代码的结果，您需要提供一个接口。
要正确使用：https://xelsoft.wordpress.com/2014/11/28/asynctask-implementation-using-callback-interface/