java - 我在哪里放置 Intent 代码？

Question

以下是我编写的用于使用 mysql 登录应用程序的 .java 文件。我在 http://easyway2in.blogspot.in/2015/07/android-mysql-database-connect.html 上找到了帮助

主 Activity .java

package com.example.soumya.attendance;

import android.app.Activity;
import android.content.Intent;
import android.os.StrictMode;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity{
    EditText ET_NAME,ET_PASS;
    String login_name,login_pass;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ET_NAME = (EditText)findViewById(R.id.editText1);
        ET_PASS = (EditText)findViewById(R.id.editText2);
    }
    public void userLogin(View view)
    {
        login_name = ET_NAME.getText().toString();
        login_pass = ET_PASS.getText().toString();
        String method = "login";
        BackgroundTask backgroundTask = new BackgroundTask(this);
        backgroundTask.execute(method,login_name,login_pass);
    }
    @Override
    public void onBackPressed() {
        return;
    }
}

后台 Activity .java

    package com.example.soumya.attendance;
        import android.app.AlertDialog;
        import android.content.Context;
        import android.content.Intent;
        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 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 reg_url = "http://10.0.2.2/webapp/register.php";
        String login_url = "http://10.0.2.2/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(reg_url);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                //httpURLConnection.setDoInput(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();
                //httpURLConnection.connect();
                httpURLConnection.disconnect();
                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();
            }
        }
    }

现在，我想添加一个 Intent 代码，这样如果用户成功登录，他/她将被带到另一个 Activity 。但是，如果我尝试将它放在 MainActivity.java 中，它不会检查是否成功登录。请帮助我。许多其他人也对来源有同样的疑问。这里我的login.php返回一个结果，通过echo通知登录是否成功。

Answer 1

很简单，

只要在登录成功时将Intent代码放在Post Execute上即可

@Override
    protected void onPostExecute(String result) {
        if(result.equals("Registration Success..."))
        {
            Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();

        //Place the Intent Code Here.

        Intent intent = new Intent("android.intent.category.LAUNCHER");
        intent.setClassName("com.your.package","com.your.package.MainActivity");
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);

        }
        else
        {
            alertDialog.setMessage(result);
            alertDialog.show();
            }
        }

快乐编码:)