Android studio 应用程序与mysql的连接
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时间：2020-08-20 09:00:46 来源:igfitidea点击:
Android studio application connection with mysql
提问by Peter
I am trying to connect my android studio app with mysql database but I am having some troubles during this. I have made a simple login and also php files wich connect with db.
我正在尝试将我的 android studio 应用程序与 mysql 数据库连接，但在此期间遇到了一些麻烦。我做了一个简单的登录，还有与 db 连接的 php 文件。
public class AnprSdkMain 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://127.0.0.1/anpr/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.main);
//setup input fields
user = (EditText)findViewById(R.id.editText1);
pass = (EditText)findViewById(R.id.editText2);
//setup buttons
mSubmit = (Button)findViewById(R.id.button1);
//register listeners
mSubmit.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.button1:
new AttemptLogin().execute();
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(AnprSdkMain.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());
Intent i = new Intent(AnprSdkMain.this, Lista.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(AnprSdkMain.this, file_url, Toast.LENGTH_LONG).show();
}
}
}
}
And login.php
和登录.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
}
And in config.inc.php
并在 config.inc.php
<?php
// These variables define the connection information for your MySQL database
// This is also for the Xampp example, if you are hosting on your own server,
//make the necessary changes (mybringback_travis, etc.)
$username = "root";
$password = "";
$host = "127.0.0.1";
$dbname = "anprscout";
// UTF-8 is a character encoding scheme that allows you to conveniently store
// a wide varienty of special characters, like ￠ or , in your database.
// By passing the following $options array to the database connection code we
// are telling the MySQL server that we want to communicate with it using UTF-8
// See Wikipedia for more information on UTF-8:
// http://en.wikipedia.org/wiki/UTF-8
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');
// A try/catch statement is a common method of error handling in object oriented code.
// First, PHP executes the code within the try block. If at any time it encounters an
// error while executing that code, it stops immediately and jumps down to the
// catch block. For more detailed information on exceptions and try/catch blocks:
// http://us2.php.net/manual/en/language.exceptions.php
try
{
// This statement opens a connection to your database using the PDO library
// PDO is designed to provide a flexible interface between PHP and many
// different types of database servers. For more information on PDO:
// http://us2.php.net/manual/en/class.pdo.php
$db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
}
catch(PDOException $ex)
{
// If an error occurs while opening a connection to your database, it will
// be trapped here. The script will output an error and stop executing.
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code
// (like your database username and password).
die("Failed to connect to the database: " . $ex->getMessage());
}
// This statement configures PDO to throw an exception when it encounters
// an error. This allows us to use try/catch blocks to trap database errors.
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// This statement configures PDO to return database rows from your database using an associative
// array. This means the array will have string indexes, where the string value
// represents the name of the column in your database.
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
// This block of code is used to undo magic quotes. Magic quotes are a terrible
// feature that was removed from PHP as of PHP 5.4. However, older installations
// of PHP may still have magic quotes enabled and this code is necessary to
// prevent them from causing problems. For more information on magic quotes:
// http://php.net/manual/en/security.magicquotes.php
if(function_exists('get_magic_quotes_gpc') && get_magic_quotes_gpc())
{
function undo_magic_quotes_gpc(&$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($_COOKIE);
}
header('Content-Type: text/html; charset=utf-8');
session_start();
The problem that is shown when run the applications are:
运行应用程序时显示的问题是：
07-28 18:15:34.815 340-347/com.birdorg.anpr.sdk.simple.camera.example E/Buffer Error﹕ Error converting result java.lang.NullPointerException
07-28 18:15:34.815 340-347/com.birdorg.anpr.sdk.simple.camera.example E/JSON Parser﹕ Error parsing data org.json.JSONException: End of input at character 0 of
07-28 18:15:34.825 340-347/com.birdorg.anpr.sdk.simple.camera.example W/dalvikvm﹕ threadid=7: thread exiting with uncaught exception (group=0x4001d800)
07-28 18:15:34.855 340-347/com.birdorg.anpr.sdk.simple.camera.example E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask.done(AsyncTask.java:200)
at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
at java.lang.Thread.run(Thread.java:1096)
Caused by: java.lang.NullPointerException
at com.birdorg.anpr.sdk.simple.camera.example.AnprSdkMain$AttemptLogin.doInBackground(AnprSdkMain.java:116)
at com.birdorg.anpr.sdk.simple.camera.example.AnprSdkMain$AttemptLogin.doInBackground(AnprSdkMain.java:80)
at android.os.AsyncTask.call(AsyncTask.java:185)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
????????????at java.util.concurrent.FutureTask.run(FutureTask.java:137)
????????????at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
????????????at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
????????????at java.lang.Thread.run(Thread.java:1096)
07-28 18:15:35.025 340-340/com.birdorg.anpr.sdk.simple.camera.example W/IInputConnectionWrapper﹕ showStatusIcon on inactive InputConnection
07-28 18:15:35.724 340-340/com.birdorg.anpr.sdk.simple.camera.example E/WindowManager﹕ Activity com.birdorg.anpr.sdk.simple.camera.example.AnprSdkMain has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@4a22d5a0 that was originally added here
android.view.WindowLeaked: Activity com.birdorg.anpr.sdk.simple.camera.example.AnprSdkMain has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@4a22d5a0 that was originally added here
at android.view.ViewRoot.<init>(ViewRoot.java:247)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
at android.view.Window$LocalWindowManager.addView(Window.java:424)
at android.app.Dialog.show(Dialog.java:241)
at com.birdorg.anpr.sdk.simple.camera.example.AnprSdkMain$AttemptLogin.onPreExecute(AnprSdkMain.java:94)
at android.os.AsyncTask.execute(AsyncTask.java:391)
at com.birdorg.anpr.sdk.simple.camera.example.AnprSdkMain.onClick(AnprSdkMain.java:73)
at android.view.View.performClick(View.java:2408)
at android.view.View$PerformClick.run(View.java:8816)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4627)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
I am new at android studio. I really need some help with this
我是 android studio 的新手。我真的需要一些帮助
回答by intrepidkarthi
回答by Peter
Building app communicating with web server so building two apps (or maybe more) communicating is one of the most difficult thing in computer programming because it's hard to know which side is buggy (and sometimes, both are...).
构建与 Web 服务器通信的应用程序，因此构建两个（或更多）应用程序的通信是计算机编程中最困难的事情之一，因为很难知道哪一方有问题（有时，两者都是......）。
I suggest you one starting point I use with great succes: start by programming, alone, the PHP side. Just call it while using URL on which you put parameter. When it will "echo", as you're calling the PHP via your web brower, you'll see the result. When this is OK, add a "log" system in you PHP. Like this:
我建议你从我使用的一个非常成功的起点开始：从编程开始，单独的 PHP 方面。只需在使用放置参数的 URL 时调用它。当它“回显”时，当您通过 Web 浏览器调用 PHP 时，您将看到结果。当这一切正常时，在您的 PHP 中添加一个“日志”系统。像这样：
function debug_log($string_db)
{
// Prepare string with date and time
$the_date = date("[ d/m/Y - H:i:s ] ");
$to_save = $the_date.$string_db."\r"; // and add the string to log
// Open file: write at he the end
$handle = fopen("call.log","a");
// Save string
fwrite($handle,$to_save,strlen($to_save));
fclose($handle); // bye bye
}
Use it as (eg): debug_log ("Inside first loop");
将其用作（例如）： debug_log ("Inside first loop");
It's very "basic", but this will save on disk and not "echo", this will not disturb the Android App but will allow you to take a look at what you PHP is doing.
这是非常“基本”的，但这将节省磁盘而不是“回声”，这不会干扰 Android 应用程序，但可以让您查看 PHP 正在做什么。
Once you have done that, turn back to the Android dev as, as this time, you will be sure that, in case of problem, it's on the Android side.
完成此操作后，请返回 Android 开发人员，因为这一次，您将确保在出现问题时，它在 Android 端。
