Home > Article > Backend Development > Detailed explanation of how PHP generates a QR code that can be logged in by scanning with the Android client
This article mainly introduces in detail whether PHP can generate a QR code that can be logged in by scanning the Android client. It has a certain reference value. Interested friends can refer to it.
Used Github The ZXing open source library with code scanning function uses the network API to generate QR code images through random numbers. The whole process goes through three steps:
1. The PHP web page generates the QR code and the corresponding random number. Store it in the database;
2. The Android client scans the code and saves the username to the location corresponding to the random number;
3. Every once in a while, PHP polls the database through Ajax to determine whether it is empty or not. If empty, the page will be redirected.
Specific code:
1. Generate a QR code image through random numbers and execute the main page of the polling operation command
<html>
<head>
<title>qrlogin</title>
<meta charset="UTF-8"/>
</head>
<body>
<?php
/**
* @author Cenquanyu
* @version 2016年5月12日
*
*/
require 'mysql_connect.php';
$randnumber = "";
for($i=0;$i<8;$i++){
$randnumber.=rand(0,9);
}
//将生成的随机数保存至数据库
mysql_query("insert into login_data (randnumber) values ('$randnumber')")
?>
<img src="http://qr.liantu.com/api.php?text=<?php echo $randnumber;?>" width="300px"/>
<input hidden="hidden" type="text" name="randnumber" id="randnumber"value="<?php echo $randnumber;?>"/>
</body>
<script>
xmlHttpRequest.onreadystatechange = function(){
if(xmlHttpRequest.status == 200 && xmlHttpRequest.readyState ==4){
result = xmlHttp.responseText;
if(result==true){//username不为空则跳转页面
window.location.href='welcome.php';
}
}
}
}
function polling(){
//执行轮询操作
var xmlHttpRequest;
if(window.XMLHttpRequest){
xmlHttpRequest = new XMLHttpRequest();
}
else{
xmlHttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
}
randnumber = document.getElementById('randnumber').value;
xmlHttpRequest.open("GET","polling.php?randnumber="+ randnumber,true);
xmlHttpRequest.send();
}
setInterval("polling()",1000);
</script>
</html>
2. Database connection page
<?php
/**
* 数据库连接文件
* @author Cenquanyu
* @version 2016年5月12日
*
*/
$con = mysql_connect("localhost","root","") or die(mysql_error());
mysql_select_db("qr_login");
?>
3 .Page that performs polling operation, jump if username is not empty
<?php
/**
* @author Cenquanyu
* @version 2016年5月12日
* 执行轮询操作，查询随机数在数据库中的相应位置的username字段为不为空
* 为空，则返回false,页面不跳转
* 不为空，则说明有用户进行了该二维码的扫码登录，页面进行跳转
*/
require 'mysql_connect.php';
$randnumber = $_GET['randnumber'];
$result = mysql_query("select * from login_data where randnumber='$randnumber'");
$row = mysql_fetch_array($result);
if($row['username']!="")
echo "true";
else
echo "false";
?>
4. Customized API, Save the client’s username
<?php
/**
* @author Cenquanyu
* @version 2016年5月12日
* 自定义API用于Android客户端扫码登录，将客户端的username保存至二维码对应的随机数在数据库中的相应位置。
* 参数：username，randnumber
* 无返回值
*/
$randnumber = $_GET('randnumber');
$username = $_GET('username');
require 'mysql_connect.php';
mysql_query("update qr_login set username='$username' where randnumber= '$randnumber'");
?>
5. Activity for the Android client to perform code scanning operations
package com.Cenquanyu.qrlogin;
import com.Cenquanyu.qrlogin.R;
import com.zxing.activity.CaptureActivity;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Paint.Cap;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
/**
* @author Cenquanyu
* @version 2016年5月12日
*
*/
public class MainActivity extends Activity implements OnClickListener {
private Button btnScan;
private EditText etUsername;
private static final String WEB_URL = "http://172.31.19.202/QRLogin/";//改成PC端相应地址
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnScan = (Button) findViewById(R.id.btnScan);
btnScan.setOnClickListener(this);
etUsername = (EditText) findViewById(R.id.etUsername);
}
@Override
public void onClick(View v) {
// 扫码操作
Intent intent = new Intent(this, CaptureActivity.class);
startActivityForResult(intent, 0);//返回结果
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK) {
String randnumber = data.getExtras().getString("result");//客户端扫码后返回扫描结果，将二维码对应的随机数取出
String username = etUsername.getText().toString();
String url = WEB_URL + "saveUsername.php?randnumber=" + randnumber
+ "&username=" + username;
HttpUtils.login(url);//访问url
}
}
}
6. Network request class
package com.Cenquanyu.qrlogin;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class HttpUtils{
public static void login(final String url){
new Thread(new Runnable() {
@Override
public void run() {
HttpURLConnection connection;
try {
connection = (HttpURLConnection) new URL(url).openConnection();
connection.setRequestMethod("GET");
connection.getInputStream();
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
} Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.
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