在 Android 应用程序中与远程 MySQL 数据库交互
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【中文标题】在 Android 应用程序中与远程 MySQL 数据库交互【英文标题】：Interacting with a Remote MySQL Database in an Android Application 【发布时间】：2013-11-06 23:24:14 【问题描述】：我目前正在处理 android 中的客户端服务器通信。 我正在编写的教程可以在以下位置找到：http://www.mybringback.com/tutorial-series/12924/android-tutorial-using-remote-databases-php-and-mysql-part-1/
为方便起见，我将只发布主 活动页面（java 和 xml） 和 注册页面（java 和 xml），因为问题与其他页面相同班级。
当我在 Eclipse 上构建并运行项目时，按下 registerlayout.xml 中的登录或注册按钮，整个应用程序将崩溃。是什么导致了这个错误？请帮忙！！！
错误代码见下方
MainActivity.java
package com.example.mysqltest;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity
implements OnClickListener
private EditText user, pass;
private Button mSubmit, mRegister;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
JSONParser jsonParser = new JSONParser();
//php login script location:
//localhost :
//testing on your device
//put your local ip instead, on windows, run CMD > ipconfig
//or in mac's terminal type ifconfig and look for the ip under en0 or en1
// private static final String LOGIN_URL = "http://xxx.xxx.x.x:1234/webservice /login.php";
//testing on Emulator:
private static final String LOGIN_URL = "http://172.18.205.34/webservice/login.php";
//testing from a real server:
//private static final String LOGIN_URL = "http://www.yourdomain.com/webservice/login.php";
//JSON element ids from repsonse of php script:
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
@Override
protected void onCreate(Bundle savedInstanceState)
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//setup input fields
user = (EditText)findViewById(R.id.getUsername);
pass = (EditText)findViewById(R.id.getPassword);
//setup buttons
mSubmit = (Button)findViewById(R.id.btnLogin);
mRegister = (Button)findViewById(R.id.btnRegister);
//register listeners
mSubmit.setOnClickListener(this);
mRegister.setOnClickListener(this);
@Override
public void onClick(View v)
// TODO Auto-generated method stub
switch (v.getId())
case R.id.btnLogin:
new AttemptLogin().execute();
break;
case R.id.btnRegister:
Intent i = new Intent(this, Register.class);
startActivity(i);
break;
default:
break;
class AttemptLogin extends AsyncTask<String, String, String>
/**
* Before starting background thread Show Progress Dialog
* */
boolean failure = false;
@Override
protected void onPreExecute()
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Attempting login...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
@Override
protected String doInBackground(String... args)
// TODO Auto-generated method stub
// Check for success tag
int success;
String username = user.getText().toString();
String password = pass.getText().toString();
try
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username", username));
params.add(new BasicNameValuePair("password", password));
Log.d("request!", "starting");
// getting product details by making HTTP request
JSONObject json = jsonParser.makeHttpRequest(
LOGIN_URL, "POST", params);
// check your log for json response
Log.d("Login attempt", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1)
Log.d("Login Successful!", json.toString());
// save user data
SharedPreferences sp = PreferenceManager
.getDefaultSharedPreferences(MainActivity.this);
Editor edit = sp.edit();
edit.putString("username", username);
edit.commit();
Intent i = new Intent(MainActivity.this, ReadComments.class);
finish();
startActivity(i);
return json.getString(TAG_MESSAGE);
else
Log.d("Login Failure!", json.getString(TAG_MESSAGE));
return json.getString(TAG_MESSAGE);
catch (JSONException e)
e.printStackTrace();
return null;
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url)
// dismiss the dialog once product deleted
pDialog.dismiss();
if (file_url != null)
Toast.makeText(MainActivity.this, file_url, Toast.LENGTH_LONG).show();
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<EditText
android:id="@+id/getPassword"
android:layout_
android:layout_
android:layout_alignLeft="@+id/getUsername"
android:layout_below="@+id/getUsername"
android:layout_marginTop="35dp"
android:ems="10"
android:inputType="textMultiLine" />
<Button
android:id="@+id/btnLogin"
android:layout_
android:layout_
android:layout_alignRight="@+id/textView1"
android:layout_centerVertical="true"
android:text="Login" />
<Button
android:id="@+id/btnRegister"
android:layout_
android:layout_
android:layout_alignBaseline="@+id/btnLogin"
android:layout_alignBottom="@+id/btnLogin"
android:layout_centerHorizontal="true"
android:text="Register" />
<TextView
android:id="@+id/textView1"
android:layout_
android:layout_
android:layout_alignParentTop="true"
android:layout_marginTop="17dp"
android:layout_toLeftOf="@+id/btnRegister"
android:text="Username:" />
<EditText
android:id="@+id/getUsername"
android:layout_
android:layout_
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/textView1"
android:ems="10"
android:inputType="textMultiLine" >
<requestFocus />
</EditText>
<TextView
android:id="@+id/textView2"
android:layout_
android:layout_
android:layout_alignLeft="@+id/getPassword"
android:layout_below="@+id/getUsername"
android:layout_marginTop="17dp"
android:text="Password:" />
</RelativeLayout>
registerlayout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_
android:layout_
android:text="Username" />
<EditText
android:id="@+id/getUsername1"
android:layout_
android:layout_
android:ems="10"
android:inputType="textMultiLine" >
<requestFocus />
</EditText>
<TextView
android:id="@+id/textView2"
android:layout_
android:layout_
android:text="Password" />
<EditText
android:id="@+id/getPassword1"
android:layout_
android:layout_
android:ems="10"
android:inputType="textMultiLine" />
<Button
android:id="@+id/btnRegister1"
android:layout_
android:layout_
android:text="Register" />
</LinearLayout>
Register.java
package com.example.mysqltest;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class Register extends Activity implements OnClickListener
private EditText user, pass;
private Button mRegister;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
JSONParser jsonParser = new JSONParser();
//php login script
//localhost :
//testing on your device
//put your local ip instead, on windows, run CMD > ipconfig
//or in mac's terminal type ifconfig and look for the ip under en0 or en1
// private static final String LOGIN_URL = "http://xxx.xxx.x.x:1234/webservice /register.php";
//testing on Emulator:
private static final String LOGIN_URL = "http://192.168.1.38/webservice/register.php";
//testing from a real server:
//private static final String LOGIN_URL = "http://www.yourdomain.com/webservice/register.php";
//ids
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
@Override
protected void onCreate(Bundle savedInstanceState)
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.registerlayout);
user = (EditText)findViewById(R.id.getUsername1);
pass = (EditText)findViewById(R.id.getPassword1);
mRegister = (Button)findViewById(R.id.btnRegister1);
mRegister.setOnClickListener(this);
@Override
public void onClick(View v)
// TODO Auto-generated method stub
new CreateUser().execute();
class CreateUser extends AsyncTask<String, String, String>
/**
* Before starting background thread Show Progress Dialog
* */
boolean failure = false;
@Override
protected void onPreExecute()
super.onPreExecute();
pDialog = new ProgressDialog(Register.this);
pDialog.setMessage("Creating User...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
@Override
protected String doInBackground(String... args)
// TODO Auto-generated method stub
// Check for success tag
int success;
String username = user.getText().toString();
String password = pass.getText().toString();
try
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username", username));
params.add(new BasicNameValuePair("password", password));
Log.d("request!", "starting");
//Posting user data to script
JSONObject json = jsonParser.makeHttpRequest(
LOGIN_URL, "POST", params);
// full json response
Log.d("Login attempt", json.toString());
// json success element
success = json.getInt(TAG_SUCCESS);
if (success == 1)
Log.d("User Created!", json.toString());
finish();
return json.getString(TAG_MESSAGE);
else
Log.d("Login Failure!", json.getString(TAG_MESSAGE));
return json.getString(TAG_MESSAGE);
catch (JSONException e)
e.printStackTrace();
return null;
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url)
// dismiss the dialog once product deleted
pDialog.dismiss();
if (file_url != null)
Toast.makeText(Register.this, file_url, Toast.LENGTH_LONG).show();
config.inc.php
<?php
// These variables define the connection information for your MySQL database
$username = "emily";
$password = "testing";
$host = "localhost";
$dbname = "webservice";
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');
try
$db = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $username, $password, $options);
catch(PDOException $ex)
die("Failed to connect to the database: " . $ex->getMessage());
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
if(function_exists('get_magic_quotes_gpc') && get_magic_quotes_gpc())
function undo_magic_quotes_gpc(&$array)
foreach($array as &$value)
if(is_array($value))
undo_magic_quotes_gpc($value);
else
$value = stripslashes($value);
undo_magic_quotes_gpc($_POST);
undo_magic_quotes_gpc($_GET);
undo_magic_quotes_gpc($_COOKIE);
header('Content-Type: text/html; charset=utf-8');
session_start();
?>
login.php
<?php
//load and connect to MySQL database stuff
require("config.inc.php");
if (!empty($_POST))
//gets user's info based off of a username.
$query = "
SELECT
id,
username,
password
FROM users
WHERE
username = :username
";
$query_params = array(
':username' => $_POST['username']
);
try
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
catch (PDOException $ex)
// For testing, you could use a die and message.
//die("Failed to run query: " . $ex->getMessage());
//or just use this use this one to product JSON data:
$response["success"] = 0;
$response["message"] = "Database Error1. Please Try Again!";
die(json_encode($response));
//This will be the variable to determine whether or not the user's information is correct.
//we initialize it as false.
$validated_info = false;
//fetching all the rows from the query
$row = $stmt->fetch();
if ($row)
//if we encrypted the password, we would unencrypt it here, but in our case we just
//compare the two passwords
if ($_POST['password'] === $row['password'])
$login_ok = true;
// If the user logged in successfully, then we send them to the private members-only page
// Otherwise, we display a login failed message and show the login form again
if ($login_ok)
$response["success"] = 1;
$response["message"] = "Login successful!";
die(json_encode($response));
else
$response["success"] = 0;
$response["message"] = "Invalid Credentials!";
die(json_encode($response));
else
?>
<h1>Login</h1>
<form action="login.php" method="post">
Username:<br />
<input type="text" name="username" placeholder="username" />
<br /><br />
Password:<br />
<input type="password" name="password" placeholder="password" value="" />
<br /><br />
<input type="submit" value="Login" />
</form>
<a href="register.php">Register</a>
<?php
?>
register.php
<?php
require("config.inc.php");
//if posted data is not empty
if (!empty($_POST))
//If the username or password is empty when the user submits
//the form, the page will die.
//Using die isn't a very good practice, you may want to look into
//displaying an error message within the form instead.
//We could also do front-end form validation from within our Android App,
//but it is good to have a have the back-end code do a double check.
if (empty($_POST['username']) || empty($_POST['password']))
// Create some data that will be the JSON response
$response["success"] = 0;
$response["message"] = "Please Enter Both a Username and Password.";
//die will kill the page and not execute any code below, it will also
//display the parameter... in this case the JSON data our Android
//app will parse
die(json_encode($response));
//if the page hasn't died, we will check with our database to see if there is
//already a user with the username specificed in the form. ":user" is just
//a blank variable that we will change before we execute the query. We
//do it this way to increase security, and defend against sql injections
$query = " SELECT 1 FROM users WHERE username = :user";
//now lets update what :user should be
$query_params = array(
':user' => $_POST['username']
);
//Now let's make run the query:
try
// These two statements run the query against your database table.
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
catch (PDOException $ex)
// For testing, you could use a die and message.
//die("Failed to run query: " . $ex->getMessage());
//or just use this use this one to product JSON data:
$response["success"] = 0;
$response["message"] = "Database Error1. Please Try Again!";
die(json_encode($response));
//fetch is an array of returned data. If any data is returned,
//we know that the username is already in use, so we murder our
//page
$row = $stmt->fetch();
if ($row)
// For testing, you could use a die and message.
//die("This username is already in use");
//You could comment out the above die and use this one:
$response["success"] = 0;
$response["message"] = "I'm sorry, this username is already in use";
die(json_encode($response));
//If we have made it here without dying, then we are in the clear to
//create a new user. Let's setup our new query to create a user.
//Again, to protect against sql injects, user tokens such as :user and :pass
$query = "INSERT INTO users ( username, password ) VALUES ( :user, :pass ) ";
//Again, we need to update our tokens with the actual data:
$query_params = array(
':user' => $_POST['username'],
':pass' => $_POST['password']
);
//time to run our query, and create the user
try
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
catch (PDOException $ex)
// For testing, you could use a die and message.
//die("Failed to run query: " . $ex->getMessage());
//or just use this use this one:
$response["success"] = 0;
$response["message"] = "Database Error2. Please Try Again!";
die(json_encode($response));
//If we have made it this far without dying, we have successfully added
//a new user to our database. We could do a few things here, such as
//redirect to the login page. Instead we are going to echo out some
//json data that will be read by the Android application, which will login
//the user (or redirect to a different activity, I'm not sure yet..)
$response["success"] = 1;
$response["message"] = "Username Successfully Added!";
echo json_encode($response);
//for a php webservice you could do a simple redirect and die.
//header("Location: login.php");
//die("Redirecting to login.php");
else
?>
<h1>Register</h1>
<form action="register.php" method="post">
Username:<br />
<input type="text" name="username" value="" />
<br /><br />
Password:<br />
<input type="password" name="password" value="" />
<br /><br />
<input type="submit" value="Register New User" />
</form>
<?php
?>
错误日志
10-28 08:52:43.894: D/dalvikvm(833): GC_FOR_ALLOC freed 71K, 8% free 2660K/2880K, paused 41ms, total 53ms
10-28 08:52:44.004: D/request!(833): starting
10-28 08:52:46.224: I/Choreographer(833): Skipped 30 frames! The application may be doing too much work on its main thread.
10-28 08:52:46.524: D/dalvikvm(833): GC_CONCURRENT freed 57K, 7% free 3009K/3212K, paused 84ms+37ms, total 297ms
10-28 08:52:47.064: E/JSON Parser(833): Error parsing data org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject
10-28 08:52:47.064: W/dalvikvm(833): threadid=15: thread exiting with uncaught exception (group=0x40a71930)
10-28 08:52:47.144: E/AndroidRuntime(833): FATAL EXCEPTION: AsyncTask #5
10-28 08:52:47.144: E/AndroidRuntime(833): java.lang.RuntimeException: An error occured while executing doInBackground()
10-28 08:52:47.144: E/AndroidRuntime(833): at android.os.AsyncTask$3.done(AsyncTask.java:299)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.util.concurrent.FutureTask.run(FutureTask.java:239)
10-28 08:52:47.144: E/AndroidRuntime(833): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.lang.Thread.run(Thread.java:856)
10-28 08:52:47.144: E/AndroidRuntime(833): Caused by: java.lang.NullPointerException
10-28 08:52:47.144: E/AndroidRuntime(833): at com.example.mysqltest.MainActivity$AttemptLogin.doInBackground(MainActivity.java:128)
10-28 08:52:47.144: E/AndroidRuntime(833): at com.example.mysqltest.MainActivity$AttemptLogin.doInBackground(MainActivity.java:1)
10-28 08:52:47.144: E/AndroidRuntime(833): at android.os.AsyncTask$2.call(AsyncTask.java:287)
10-28 08:52:47.144: E/AndroidRuntime(833): at java.util.concurrent.FutureTask.run(FutureTask.java:234)
10-28 08:52:47.144: E/AndroidRuntime(833): ... 4 more
10-28 08:52:47.864: I/Choreographer(833): Skipped 87 frames! The application may be doing too much work on its main thread.
10-28 08:52:50.844: E/WindowManager(833): Activity com.example.mysqltest.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView40d24b58 V.E..... R.....ID 0,0-563,96 that was originally added here
10-28 08:52:50.844: E/WindowManager(833): android.view.WindowLeaked: Activity com.example.mysqltest.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView40d24b58 V.E..... R.....ID 0,0-563,96 that was originally added here
10-28 08:52:50.844: E/WindowManager(833): at android.view.ViewRootImpl.<init>(ViewRootImpl.java:354)
10-28 08:52:50.844: E/WindowManager(833): at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:216)
10-28 08:52:50.844: E/WindowManager(833): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
10-28 08:52:50.844: E/WindowManager(833): at android.app.Dialog.show(Dialog.java:281)
10-28 08:52:50.844: E/WindowManager(833): at com.example.mysqltest.MainActivity$AttemptLogin.onPreExecute(MainActivity.java:106)
10-28 08:52:50.844: E/WindowManager(833): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
10-28 08:52:50.844: E/WindowManager(833): at android.os.AsyncTask.execute(AsyncTask.java:534)
10-28 08:52:50.844: E/WindowManager(833): at com.example.mysqltest.MainActivity.onClick(MainActivity.java:80)
10-28 08:52:50.844: E/WindowManager(833): at android.view.View.performClick(View.java:4204)
10-28 08:52:50.844: E/WindowManager(833): at android.view.View$PerformClick.run(View.java:17355)
10-28 08:52:50.844: E/WindowManager(833): at android.os.Handler.handleCallback(Handler.java:725)
10-28 08:52:50.844: E/WindowManager(833): at android.os.Handler.dispatchMessage(Handler.java:92)
10-28 08:52:50.844: E/WindowManager(833): at android.os.Looper.loop(Looper.java:137)
10-28 08:52:50.844: E/WindowManager(833): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-28 08:52:50.844: E/WindowManager(833): at java.lang.reflect.Method.invokeNative(Native Method)
10-28 08:52:50.844: E/WindowManager(833): at java.lang.reflect.Method.invoke(Method.java:511)
10-28 08:52:50.844: E/WindowManager(833): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-28 08:52:50.844: E/WindowManager(833): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-28 08:52:50.844: E/WindowManager(833): at dalvik.system.NativeStart.main(Native Method)
10-28 08:52:50.844: I/Choreographer(833): Skipped 73 frames! The application may be doing too much work on its main thread.
【问题讨论】：
调试 101：com.example.mysqltest.MainActivity$AttemptLogin.doInBackground(MainActivity.java:128) 行是什么？
【参考方案1】：
你是 Asyntask 获取 url 参数，但你没有在 execute 方法中发送 urlnew AttemptLogin().execute(LOGIN_URL);
@Override
public void onClick(View v)
// TODO Auto-generated method stub
switch (v.getId())
case R.id.btnLogin:
-> new AttemptLogin().execute(LOGIN_URL);
break;
case R.id.btnRegister:
Intent i = new Intent(this, Register.class);
startActivity(i);
break;
default:
break;
【讨论】：
我已经按照你的方式完成了，但是当我按下任一按钮时应用程序仍然崩溃:'(请帮助我！！ @Nambi ：这无关紧要，因为 SO 在 doInBackground 方法中从不引用args。【参考方案2】：
当我遇到“The value <br...”这个问题时，我遇到了另一个错误，不记得其余的了，但是我发现的问题是在 PHP 中。在您的 Login.PHP 文件中，您可以看到“$validated_info = false;”，但是，您实际上使用的是“$login_ok”作为布尔变量。无论您在哪里看到“$login_ok”，将其更改为“$validated_info”。或将“$validated_info”更改为“$login_ok”。这暂时修复了我的问题，但是当输入的详细信息不在数据库中时，我会收到您的错误。
【讨论】：
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