我的BackgroundTask和RegisterActivity中的运行时错误

Question

崩溃的开始

string

这些文件的链接： https://drive.google.com/open?id=0B8xoxKUDN5w3SjJsYnVqdmd0bEU

Answer 1

我建议您使用Volley Library来实现登录 - 注册活动。 这是Android开发的最新趋势，比过去的方法更容易。 我将举例说明注册活动：

我的register.xml：

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="@dimen/activity_horizontal_margin"
    android:background="@drawable/icon13">

    <EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="textPersonName"
    android:ems="10"
    android:maxLength="16"
    android:id="@+id/etName"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:hint="Όνομα" />

    <EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/etUsername"
    android:maxLength="16"
    android:layout_below="@+id/etName"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:hint="Όνομα Χρήστη" />

    <EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="textPassword"
    android:ems="10"
    android:id="@+id/etPassword"
    android:maxLength="16"
    android:layout_below="@+id/etUsername"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:hint="Κωδικός" />





    <EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:ems="10"
    android:id="@+id/etAge"
    android:maxLength="3"
    android:layout_below="@+id/etPassword"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:hint="Ηλικία" />




    <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Εγγραφή"
    android:id="@+id/bRegister"
    android:layout_below="@+id/etAge"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignRight="@+id/etAge"
    android:layout_alignEnd="@+id/etAge"
    android:layout_gravity="center"
    style="@style/Buttonlogo"/>



    <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Πίσω"
    android:id="@+id/backRegister"
    android:layout_below="@+id/etAge"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignRight="@+id/etAge"
    android:layout_alignEnd="@+id/etAge"
    android:layout_gravity="center"
    android:layout_margin="20dp"
    android:onClick="OnClickBackButton"
    style="@style/Buttonlogo"/>


</LinearLayout>

我的RegisterActivity.java：

package com.example.sakis.loginregister;

import android.app.AlertDialog;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;

public class RegisterActivity extends AppCompatActivity {

/*** Binary Semaphore lock is used to prevent fast-click.  ***/

int lock=1;
String username="";
MediaPlayer md;
int age;
String age_of_player;
String password="";
String name="";
Handler mHandler=new Handler();

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_register);

    md = MediaPlayer.create(RegisterActivity.this, R.raw.tick);

    final EditText etAge = (EditText) findViewById(R.id.etAge);
    final EditText etName = (EditText) findViewById(R.id.etName);
    final EditText etUsername = (EditText) findViewById(R.id.etUsername);
    final EditText etPassword = (EditText) findViewById(R.id.etPassword);
    final Button bRegister = (Button) findViewById(R.id.bRegister);

    bRegister.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            if (lock == 1) {

                md.release();
                md = MediaPlayer.create(RegisterActivity.this, R.raw.tick);
                md.start();
                lock = 0;
                name = etName.getText().toString();
                username = etUsername.getText().toString();
                age_of_player = etAge.getText().toString();
                password = etPassword.getText().toString();


                 if (username.matches("") || name.matches("") || password.matches("") || age_of_player.matches("")) {

                     AlertDialog.Builder builder1 = new AlertDialog.Builder(RegisterActivity.this,R.style.myBackgroundStyle);
                     builder1.setMessage("Συμπλήρωσε όλα τα πεδία")
                             .setNegativeButton("Ξαναπροσπάθησε", null)
                             .create()
                             .show();

                    Runnable runnable = new Runnable() {

                        @Override
                        public void run() {

                             lock = 1;

                        }

                    };
                    mHandler.postDelayed(runnable, 1000);

            } else {

                    age = Integer.parseInt(age_of_player);

                     /***Insert new user to Database. ***/

                    Response.Listener<String> responseListener = new Response.Listener<String>() {

                    @Override
                    public void onResponse(String response) {

                        try {

                            JSONObject jsonResponse = new JSONObject(response);
                            boolean success = jsonResponse.getBoolean("success");

                            if (success) {

                                Intent intent = new Intent(RegisterActivity.this, LoginActivity.class);
                                RegisterActivity.this.startActivity(intent);
                                finish();

                            } else {

                                AlertDialog.Builder builder = new AlertDialog.Builder(RegisterActivity.this,R.style.myBackgroundStyle);
                                builder.setMessage("Όνομα χρήστη κατειλημμένο")
                                        .setNegativeButton("Ξαναπροσπάθησε", null)
                                        .create()
                                        .show();

                                /***Set lock back to value '1' .***/

                                Runnable runnable = new Runnable() {

                                    @Override
                                    public void run() {

                                        lock = 1;

                                    }

                                };
                                mHandler.postDelayed(runnable, 1000);

                            }

                        } catch (JSONException e) {

                            e.printStackTrace();

                        }
                    }
                };

                RegisterRequest registerRequest = new RegisterRequest(name, username, age, password, responseListener);
                RequestQueue queue = Volley.newRequestQueue(RegisterActivity.this);
                queue.add(registerRequest);
            }
        }

        }

    });

}

public void OnClickBackButton(View view)  {

    if(lock==1) {

        md.release();
        md = MediaPlayer.create(RegisterActivity.this, R.raw.tick);
        md.start();
        lock=0;

        Intent backregisterintent = new Intent(this, LoginActivity.class);
        startActivity(backregisterintent);
        finish();

    }
}

/*** Mobile-phone back button method .***/

public void onBackPressed()   {

    if(lock==1) {

        md.release();
        md = MediaPlayer.create(RegisterActivity.this, R.raw.tick);
        md.start();
        lock=0;

        Intent backregisterintent = new Intent(this, LoginActivity.class);
        startActivity(backregisterintent);
        finish();

    }
}

}

我的RegisterRequest.java类：

  package com.example.sakis.loginregister;



import com.android.volley.Response;
import com.android.volley.toolbox.StringRequest;
import java.util.HashMap;
import java.util.Map;

public class RegisterRequest extends StringRequest {

    private static final String REGISTER_REQUEST_URL = "http://Your_Server_Name/Register.php";
    private Map<String, String> params;

    public RegisterRequest(String name, String username, int age, String password, Response.Listener<String> listener) {

    super(Method.POST, REGISTER_REQUEST_URL, listener, null);
    params = new HashMap<>();
    params.put("name", name);
    params.put("username", username  );
    params.put("age", age + "");
    params.put("password", password);

}

   @Override
   public Map<String, String> getParams() {

       return params;

   }
 }

我的Register.php：

<?php

 $connect = mysqli_connect("mysql.hostinger.gr", "username", "password", "database_name");



$name = $_POST["name"];
$username = $_POST["username"];
$age = $_POST["age"];
$password = $_POST["password"];

function registerUser()   {

    global $connect, $name, $age, $username, $password;

    $statement = mysqli_prepare($connect, "INSERT INTO User (name,username,age, password) VALUES (?, ?, ?, ?)");
    mysqli_stmt_bind_param($statement, "ssis", $name, $username, $age, $password);
    mysqli_stmt_execute($statement);
    mysqli_stmt_close($statement);  

};

function usernameAvailable() {

    global $connect, $username;
    $statement = mysqli_prepare($connect, "SELECT * FROM User WHERE username = ?"); 
    mysqli_stmt_bind_param($statement, "s", $username);
    mysqli_stmt_execute($statement);
    mysqli_stmt_store_result($statement);
    $count = mysqli_stmt_num_rows($statement);
    mysqli_stmt_close($statement); 

    if ($count < 1){

        return true; 

    }
    else {

        return false; 

    }
};

$response = array();
$response["success"] = false;  

if (usernameAvailable()){

     registerUser();
    $response["success"] = true;  

}

print_r(json_encode($response));
?>

您可以根据自己的需要编辑我的示例。您也可以一步一步地遵循这个好的教程： https://www.youtube.com/watch?v=QxffHgiJ64M&list=PLe60o7ed8E-TztoF2K3y4VdDgT6APZ0ka