我正在尝试创建一个登录应用程序 MySQL database
. 它可以完美地登录。但问题是,如果不能连接到服务器应用程序崩溃!我使用asynctask类在后台连接服务器。看下面的代码。
import android.content.Context;
import android.os.AsyncTask;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
public class Background_Worker extends AsyncTask<String,Void,String> {
Context context;
String type;
Background_Worker(Context context){this.context = context;}
@Override
protected String doInBackground(String... strings) {
type = strings[0];
String login_url = "http://myserver420.com/user_info/login_user.php";
if (type.equals("check_login_info")){
try {
String username = strings[1];
String password = strings[2];
URL url = new URL(login_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data = URLEncoder.encode("username","UTF-8")+"="+URLEncoder.encode(username,"UTF-8")+"&"
+URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
String result="";
String line="";
while((line = bufferedReader.readLine())!= null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
return result;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPreExecute() {}
@Override
protected void onPostExecute(String result) {
// login user
if (type.equals("check_login_info")){
if (result.equals("login_success")){((Login) context).login_success();}
else if (result.equals("login_not_success")){((Login) context).login_not_success();}
else {}
}
else{}
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
}
在这种情况下,当它可以连接到服务器时,它如何才能完美地工作。但如果我关闭设备网络,它就会崩溃!现在我怎样才能解决撞车问题?谢谢你的回复。
1条答案
按热度按时间slmsl1lt1#
将此方法放入代码中。如果它返回true,则执行代码,否则将给出未连接到网络的toast。