Question

我找到了用于将Android App连接到SQL数据库以进行登录的基本教程，以便我可以理解基本原理。在这种情况下，我使用了WampServer和php文件来连接数据。

作为参考，以下是php文件：

conn.php：

<?php 
$db_name = "schoolinfo";
$mysql_username = "root";
$mysql_password = "";
$server_name = "localhost";
$conn = mysqli_connect($server_name, $mysql_username, $mysql_password, $db_name);
?>

login.php：

<?php
require "conn.php";
$user_name = $_POST["user_name"];
$user_pass = $_POST["password"];
$mysql_qry = "select * from studentinfo where ID like '$user_name' and password like '$user_pass';";
$result = mysqli_query($conn, $mysql_qry);
if(mysqli_num_rows($result) > 0) {
    echo "login successful";
}
else {
    echo "login failed";
}
?>

当我使用http://localhost/login.php测试php文件并将其$user_name和$user_pass设置为静态字符串时，php文件可以独立工作。但是，在测试来自Android应用程序项目的登录名时，我得到了一些奇怪的结果。当您尝试登录时，会弹出一个带有标题和消息的alertDialog。奇怪的是，只有标题弹出了-让我相信在应用程序和php文件之间它们出了问题。如何解决此错误的连接？

有关进一步的参考，请参见以下Java文件：

MainActivity：

public class MainActivity extends AppCompatActivity {

EditText UserEt, PasswordEt;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    UserEt = findViewById(R.id.editUser);
    PasswordEt = findViewById(R.id.editPassword);
}

public void onLogin(View view) {
    String username = UserEt.getText().toString();
    String password = PasswordEt.getText().toString();
    String type = "login";
    BackgroundWorker backgroundWorker = new BackgroundWorker(this);
    backgroundWorker.execute(type, username, password);

}
}

BackgroundWorker.java：

public class BackgroundWorker extends AsyncTask<String,Void,String> {
Context context;
AlertDialog alertDialog;
BackgroundWorker (Context ctx) {
    context = ctx;
}

@Override
protected String doInBackground(String... params) {
    String type = params[0];
    String login_url = "http://ip_address/login.php";
    if(type.equals("login")) {
        try {
            String user_name = params[1];
            String password = params[2];
            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 post_data = URLEncoder.encode("user_name","UTF-8")+"="+URLEncoder.encode(user_name,"UTF-8")+"&"
                    +URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
            String result="";
            String line="";
            while((line = bufferedReader.readLine())!= null) {
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;
}

@Override
protected void onPreExecute() {
    alertDialog = new AlertDialog.Builder(context).create();
    alertDialog.setTitle("Login Status");

}


@Override
protected void onPostExecute(String result) {

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

@Override
protected void onProgressUpdate(Void... values) {
    super.onProgressUpdate(values);
}
}

**编辑：** 我遍历了我的调用堆栈，发现有一个错误（通过try-catch语句捕获）说：不允许对ip_adress的明文HTTP通信。

当我在清单中切换android:usesCleartextTraffic = "true"时，它起作用了。这是因为Android sdk 28发生了变化。完成项目后，我将切换到https。

验证连接到MySQL数据库的Android App的登录状态

0 个答案: