使用 Android 连接到远程 MySQL 数据库

Question

我的服务器中有一个 MySQL 数据库。我想知道如何连接到远程数据库并将数据显示到我的 Android 应用程序中。

我知道这是一种使用 WebService 或直接的方式，但我不知道更多。

我有一个用 Php 编写的脚本，位于服务器中，可以连接到数据库

$db = mysql_connect("localhost", "UserName", "Password") or die (mysql_error());  
mysql_select_db("NameofDB",$db) or die (mysql_error());

感谢您的帮助！

Answer 1

Android 应用程序端：

private ArrayList<String> receiveData(String file, ArrayList<NameValuePair> data)
{
    InputStream is = null;
    ArrayList<String> output = new ArrayList<String>();
    String line = null;

    //Connect and obtain data via HTTP.
    try
    {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://www.blah.com/"+file);
        httppost.setEntity(new UrlEncodedFormEntity(data));
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();

    }
    catch(Exception e)
    {
        Log.e("log_tag", "Error in http connection "+e.toString());
    }

    //Parse data into ArrayList and return.
    try
    {
        BufferedReader reader = 
            new BufferedReader(new InputStreamReader(is,"iso-8859-1"));

        while ((line = reader.readLine()) != null) 
        {
            //Parse data into tokens and removing unimportant tokens.
            StringTokenizer st = new StringTokenizer(line, delims, false);

            while(st.hasMoreTokens())
            {
                String token = st.nextToken();
                output.add(token);
            }
        }

        is.close();
        //Log output of data in LogCat.
        Log.d("DATA","DATA:"+output);

    }
    catch(Exception e)
    {
        Log.e("log_tag", "Error converting result "+e.toString());
    }
    return output;
}

/**
 * Gets all  data from GetAllData.php
 * @return output - ArrayList containing  data.
 */
public ArrayList<String> getAllData(String row)
{
    fileName = "GetAllData.php";

    //Add arguments to arrayList<NameValuePairs> so we can encode the data and send it on.
    ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
    nameValuePairs.add(new BasicNameValuePair("row", row));

    ArrayList<String> output = this.receiveData(fileName, nameValuePairs);
    return output;
}

服务器端：

那么服务器上的 GetAllData.php 文件是：

<?php
/*
 * What this file does is it:
 * 1) Creates connection to database.
 * 2) Gets data from database.
 * 3) Encodes data to JSON. So this data can then be used by Android Application.
 * 4) Close database connection.
 */
 require_once $_SERVER['DOCUMENT_ROOT'].'/Clarity/Connection.php';
 require_once $_SERVER['DOCUMENT_ROOT'].'/Clarity/ReceiveAPI.php';

 $server = new Connection();
 $receive = new ReceiveAPI();

 //Retrieve information.
 $row = $_POST['row'];

//Connect to database.
$server->connectDB();
$output = $receive->getAllData($row); //basically method to query database.
print(json_encode($output)); //output is result of the query given back to app.

//Disconnect from database.
$server->disconnectDB();
?>

这是我最近使用的一个示例。只需要在 php 文件中注明即可。我导入 Connection.php
这仅处理与数据库的连接。因此，只需将其替换为连接 MYSQL 数据库的代码即可。我还导入了 SendAPI.php （您可以忽略它）这只是我用于发送数据的类。基本上它包含了一些我想使用的查询。如sendAccelerationData()。基本上类与存储过程类似。

我如何连接到数据库是在我的 Connection.php 类中。

//Connect to a database.
public function connectDB()
{
    //Connect to SQL server.
    $this->connection = mysql_connect($this->hostName,$this->user,$this->password);

    if (!$this->connection) 
    {
        die('Could not connect: ' . mysql_error());
    }
    //Print("Connected to MySQL. </br>");

    //Select Database to query.
    $db_selected = mysql_select_db($this->database);
    if (!$db_selected) 
    {
        die('Could not select database' . mysql_error());
    }
    //Print("Database \"$this->database\" selected. </br>");
}

//Disconnect from database.
public function disconnectDB() 
{
    mysql_close($this->connection);
}
}

请注意，在错误消息中，我打印出了数据库的架构，例如数据库名称/表名称。这只是故障排除。我建议反对这一点。您不想向用户显示该信息。