我在搜索我想要的东西时非常糟糕所以我决定在这里问一下。我的问题是，从数据库中获取数据时是否可以显示进度条？我在获取数据时使用典型代码（将值传递给php，php将执行查询并将其再次传递给android）
编辑（我已尝试添加proggressdialog，但现在的问题是加载的数据将首先出现在进度对话框之前，这是我的AsyncTask代码）
public class getClass extends AsyncTask<String, Void, String> {
public getClass()
{
pDialog = new ProgressDialog(getActivity());
}
URLConnection connection = null;
String command;
Context context;
String ip = new returnIP().getIpAddresss();
String link = "http://" + ip + "/android/getClass.php";//ip address/localhost
public URLConnection getConnection(String link) {
URL url = null;
try//retrieves link from string
{
url = new URL(link);
} catch (MalformedURLException e) {
e.printStackTrace();
}
URLConnection connection = null;
try//opens the url link provided from the "link" variable
{
connection = url.openConnection();
} catch (IOException e) {
e.printStackTrace();
}
connection.setDoOutput(true);
return connection;
}
public String getResult(URLConnection connection, String logs) {
//this is the functions that retrieves what the php file echoes
//everything that php throws, the phone receives
String result = "";
OutputStreamWriter wr = null;
try {
wr = new OutputStreamWriter(connection.getOutputStream());//compiles data to be sent to the receiver
} catch (IOException e) {
e.printStackTrace();
}
try {
wr.write(logs);
} catch (IOException e) {
e.printStackTrace();
}
try {
wr.flush();//clears the cache-esque thingy of the writer
} catch (IOException e) {
e.printStackTrace();
}
BufferedReader reader = null;
try {
reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
StringBuilder sb = new StringBuilder();
String line = null;
//Read server response
try {
while ((line = reader.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
}
result = sb.toString();
return result;
}
@Override
protected void onPreExecute() {
pDialog.setMessage("Loading...");
pDialog.show();
}
@Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
String result = "";
//Toast.makeText(View_Classes.this, "ako n una", Toast.LENGTH_LONG).show();
try {
//first data sent is sent in command
command = (String) arg0[0];//it's in array, because everything you input here is placed in arrays
//Toast.makeText(View_Classes.this, "andtio n me", Toast.LENGTH_LONG).show();
if (command == "getCourses") {
connection = getConnection(link);
String logs = "";
logs = "&command=" + URLEncoder.encode(command, "UTF-8");
logs += "&username=" + URLEncoder.encode(username, "UTF-8");
result = getResult(connection, logs);
} else if (command == "getSections") {
connection = getConnection(link);
String logs = "";
logs = "&command=" + URLEncoder.encode(command, "UTF-8");
logs += "&username=" + URLEncoder.encode(username, "UTF-8");
logs += "&course=" + URLEncoder.encode(course, "UTF-8");
result = getResult(connection, logs);
}
return result;
} catch (Exception e) {
return result;
}
}
@Override
protected void onPostExecute(String result) {//this is going to be the next function to be done after the doInBackground function
// TODO Auto-generated method stub
if (pDialog.isShowing()) {
pDialog.dismiss();
}
if (result.equalsIgnoreCase(""))//if there's nothing to return, the text "No records" are going to be thrown
{
} else //Array adapter is needed, to be a place holder of values before passing to spinner
{
}
}
}
答案 0 :(得分：0)
您是否尝试使用AsyncTask？
您可以在preExecute方法上显示进度条，然后在postExecute上隐藏它。您可以在doInBackground方法中进行查询。
答案 1 :(得分：0)
除了@ torque203指出的，我建议你检查一下 http://developer.android.com/reference/android/os/AsyncTask.html#onProgressUpdate(Progress...) 此方法是为此目的创建的，向用户显示进度。
答案 2 :(得分：0)
来自开发者文档：
private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
@Override
protected void onPreExecute() {
//show progress bar here
}
protected Long doInBackground(URL... urls) {
//Pass value to PHP here
//get values from your PHP
}
protected void onPostExecute(Long result) {
//Here you are ready with your PHP value. Dismiss progress bar here.
}
}
答案 3 :(得分：0)
public void onPreExecute() {
Progress Dialog pDialog = new ProgressDialog(this);
pDialog.setMessage("Loading...");
pDialog.show();
}
public void doInBackground() {
//do your JSON Coding
}
public void onPostExecute() {
Progress Dialog pDialog = new ProgressDialog(this);
pDialog.setMessage("Loading...");
pDialog.show();
}
答案 4 :(得分：0)
public URLConnection getConnection(String link) {
URL url = null;
try//retrieves link from string
{
url = new URL(link);
} catch (MalformedURLException e) {
e.printStackTrace();
}
URLConnection connection = null;
try//opens the url link provided from the "link" variable
{
connection = url.openConnection();
} catch (IOException e) {
e.printStackTrace();
}
connection.setDoOutput(true);
return connection;
}
public String getResult(URLConnection connection, String logs) {
//this is the functions that retrieves what the php file echoes
//everything that php throws, the phone receives
String result = "";
OutputStreamWriter wr = null;
try {
wr = new OutputStreamWriter(connection.getOutputStream());//compiles data to be sent to the receiver
} catch (IOException e) {
e.printStackTrace();
}
try {
wr.write(logs);
} catch (IOException e) {
e.printStackTrace();
}
try {
wr.flush();//clears the cache-esque thingy of the writer
} catch (IOException e) {
e.printStackTrace();
}
BufferedReader reader = null;
try {
reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
StringBuilder sb = new StringBuilder();
String line = null;
//Read server response
try {
while ((line = reader.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
}
result = sb.toString();
return result;
}
public class getClass extends AsyncTask<String, Void, String> {
@Override
protected void onPreExecute() {
pDialog.setMessage("Loading...");
pDialog.show();
URLConnection connection = null;
String command;
Context context;
String ip = new returnIP().getIpAddresss();
String link = "http://" + ip + "/android/getClass.php";//ip address/localhost
}
@Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
String result = "";
//Toast.makeText(View_Classes.this, "ako n una", Toast.LENGTH_LONG).show();
try {
//first data sent is sent in command
command = (String) arg0[0];//it's in array, because everything you input here is placed in arrays
//Toast.makeText(View_Classes.this, "andtio n me", Toast.LENGTH_LONG).show();
if (command == "getCourses") {
connection = getConnection(link);
String logs = "";
logs = "&command=" + URLEncoder.encode(command, "UTF-8");
logs += "&username=" + URLEncoder.encode(username, "UTF-8");
result = getResult(connection, logs);
} else if (command == "getSections") {
connection = getConnection(link);
String logs = "";
logs = "&command=" + URLEncoder.encode(command, "UTF-8");
logs += "&username=" + URLEncoder.encode(username, "UTF-8");
logs += "&course=" + URLEncoder.encode(course, "UTF-8");
result = getResult(connection, logs);
}
return result;
} catch (Exception e) {
return result;
}
}
@Override
protected void onPostExecute(String result) {//this is going to be the next function to be done after the doInBackground function
// TODO Auto-generated method stub
if (pDialog.isShowing()) {
pDialog.dismiss();
}
if (result.equalsIgnoreCase(""))//if there's nothing to return, the text "No records" are going to be thrown
{
} else //Array adapter is needed, to be a place holder of values before passing to spinner
{
}
}
}