Android 加载listview活动需要很长时间，并在显示之前显示黑屏
我创建了一个应用程序，该应用程序从服务器上获取带有Android 加载listview活动需要很长时间，并在显示之前显示黑屏,android,Android,我创建了一个应用程序，该应用程序从服务器上获取带有AsyncTask的JSON。当用户单击按钮时，应用程序启动新活动并从服务器下载数据，并在列表视图中显示为项目。问题是当我打开新的活动时加载时间太长。当按下按钮时，应用程序冻结约1或2秒，然后再显示黑屏2/3秒。之后会显示活动，但速度非常慢。每次用户滚动或按下按钮以显示自定义适配器的更多选项时，它都会冻结。有没有办法让应用程序更流畅？下载的Json数据只是简单的JSONArray，带有JSONObjects，它有两个字符串值和一种HTML格式。这
AsyncTask列表视图中显示为项目。问题是当我打开新的活动时
加载时间太长。当按下按钮时，应用程序冻结约1或2秒，然后再显示黑屏2/3秒。之后会显示活动，但速度非常慢。每次用户滚动或按下按钮以显示自定义适配器的更多选项时，它都会冻结。有没有办法让应用程序更流畅？下载的Json数据只是简单的JSONArray
，带有JSONObjects
，它有两个字符串值和一种HTML格式。这3个值将显示给用户
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;
}
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;
}
异步任务类的一部分
@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;
}
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);
}
}
}
适配器
是自定义的，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sqlite的内容，而那个应用程序并没有那个么慢。但当我打开这个活动时，它会显著减慢。我还注意到，当我按下后退按钮时，需要很长时间才能回到上一个屏幕 问题出在getSuggestionList
函数中。在这个函数中，您将调用getSuggestionsFromAPI.execute（clientsSuggestionsUrl.get（）使您的代码再次同步。我的意思是你的代码正在等待这个代码被执行
一种方法（不是正确的方法，而是简单的方法）：您可以调用newgetSuggestions（）.getSuggestionList（）在新线程中
第二种方法是调用getSugestionsFromApi.execute（ClientsSugestionsUrl）
而不调用get（）
函数。但要获得代码的结果，您需要提供一个接口。
要获得正确的用法：从调用适配器类的位置发布类文件。@Naveen我将SuggestionListAdapter添加到最后一个列表“活动”中。我还更新了帖子并添加了标准的SuggestionList类。请粘贴整个类。@Naveen我更新了帖子谢谢！它起作用了！我使用了第二个选项和实现接口。