Question

我用android studio制作了简单的android登录应用程序。数据存储在在线服务器（MySQL数据库）中。注册和登录过程表现良好。我想知道如何在登录成功时打开活动。我试过这个代码，它给了我错误。

protected void onPostExecute(String result) {

if (result.equals("Registration Success"))
    {

        Toast.makeText(ctx,result,Toast.LENGTH_LONG).show();
    }

    else {

       // alertDialog.setMessage(result);
       // alertDialog.show();

        Toast.makeText(ctx,result,Toast.LENGTH_LONG).show();
        Intent intent = new Intent(BackgroundTask.this,home.class);
        StartAcitivity(intent);

这是后台任务类的完整代码

    package uc.venusha.com.loginsystem;

    import android.content.Context;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.support.v7.app.AlertDialog;
    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;

    /**
     * Created by Venusha on 11/3/2017.
     */

    public class BackgroundTask extends AsyncTask<String,Void,String> {
        AlertDialog alertDialog;
        Context ctx;
        BackgroundTask(Context ctx)
        {

         this.ctx=ctx;
        }

        @Override
        protected void onPreExecute() {
           alertDialog = new AlertDialog.Builder(ctx).create();
            alertDialog.setTitle("Login Information");
        }


        @Override
        protected String doInBackground(String... params) {
            String ref_url= "http://ictguru.000webhostapp.com/webapp/register.php";
            String login_url="http://ictguru.000webhostapp.com/webapp/login.php";
            String method = params[0];
            if (method.equals("register"))
            {
                String name = params[1];
                String user_name=params[2];
                String user_pass=params[3];

                try {
                    URL url= new URL(ref_url);
                    HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                    httpURLConnection.setRequestMethod("POST");
                    httpURLConnection.setDoOutput(true);
                    OutputStream OS = httpURLConnection.getOutputStream();
                    BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(OS,"UTF-8"));
                    String data = URLEncoder.encode("user","UTF-8") + "="  + URLEncoder.encode(name, "UTF-8") + "&" +
                            URLEncoder.encode("user_name","UTF-8") + "=" + URLEncoder.encode(user_name, "UTF-8") + "&" +
                            URLEncoder.encode("user_pass","UTF-8") + "=" + URLEncoder.encode(user_pass, "UTF-8");
                    bufferedWriter.write(data);
                    bufferedWriter.flush();
                    bufferedWriter.close();
                    OS.close();
                    InputStream IS =httpURLConnection.getInputStream();
                    IS.close();
                    return "Registration Success";





            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                    e.printStackTrace();
                }

            }
            else if(method.equals("login")){

                String login_name=params[1];
                String login_pass=params[2];

                try {
                    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 data = URLEncoder.encode("login_name","UTF-8") +"="+URLEncoder.encode(login_name,"UTF-8")+"&"+
                            URLEncoder.encode("login_pass","UTF-8")+"="+URLEncoder.encode(login_pass,"UTF-8");
                    bufferedWriter.write(data);
                    bufferedWriter.flush();
                    bufferedWriter.close();
                    outputStream.close();

                    InputStream inputStream = httpURLConnection.getInputStream();
                    BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
                    String response ="";
                    String line ="";
                    while ((line=bufferedReader.readLine())!=null) {

                        response+=line;
                    }

                    bufferedReader.close();
                    inputStream.close();
                    httpURLConnection.disconnect();
                    return response;


                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
             return null;
        }

        @Override

        protected void onProgressUpdate(Void... values){
            super.onProgressUpdate(values);
        }

        @Override
        protected void onPostExecute(String result) {



            if (result.equals("Registration Success"))
            {

                Toast.makeText(ctx,result,Toast.LENGTH_LONG).show();
            }

            else {

               // alertDialog.setMessage(result);
               // alertDialog.show();

                Toast.makeText(ctx,result,Toast.LENGTH_LONG).show();
               Intent intent = new Intent(BackgroundTask.this,home.class);
                StartAcitivity(intent);





            }

        }


    }

Answer 1

尝试Intent intent=new Intent(ctx,home.class)和而不是StartAcitvity(intent)，请尝试使用ctx.startActivity(intent)

在else语句中打开新活动

1 个答案: