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Tutorial on using PHP and Baidu Map API to implement taxi trajectory display function

PHPzOriginal: 2023-07-31 13:53:101265browse

Tutorial on using PHP and Baidu Map API to implement the taxi trajectory display function

Abstract:
This tutorial will introduce how to use PHP and Baidu Map API to implement the taxi trajectory display function. We will use Baidu Maps' JavaScript API to draw the map and obtain taxi trajectory data from the database through PHP. Eventually, we will show the movement trajectory of each taxi and add some interactive features.

Preparation work
Before you start, you need to prepare the following work:
Install PHP and database (such as MySQL)
Register a Baidu Map developer account , and get the API key
Prepare taxi trajectory data
Create database
First, we need to create a database table to store the taxi trajectory data. Suppose we need to store the longitude, latitude and timestamp data of each taxi. Create a table named "tracks" and add the following fields:
```
CREATE TABLE `tracks` (
  `id` INT(11) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  `car_id` INT(11) NOT NULL,
  `lng` DOUBLE NOT NULL,
  `lat` DOUBLE NOT NULL,
  `timestamp` INT(11) NOT NULL
);
```
Insert test data
Insert some test data into the database table created in the previous step for subsequent display trajectory. For example:
```
INSERT INTO `tracks` (`car_id`, `lng`, `lat`, `timestamp`) VALUES
(1, 116.404, 39.915, 1600000000),
(1, 116.406, 39.920, 1600000100),
...
```

Create a PHP script
Create a PHP script named "map.php" to obtain trajectory data from the database and return it to the front end. Add the following code to "map.php":

<?php
// 连接到数据库
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "your_database";
$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
 die("Connection failed: " . $conn->connect_error);
}

// 获取轨迹数据
$carId = $_GET['car_id']; // 从前端获取参数
$sql = "SELECT * FROM tracks WHERE car_id = $carId"; // 假设每辆出租车有一个唯一的ID
$result = $conn->query($sql);
$tracks = [];

if ($result->num_rows > 0) {
 while($row = $result->fetch_assoc()) {
     $tracks[] = $row;
 }
} else {
 echo "No tracks found.";
}

// 返回JSON格式的轨迹数据
header('Content-Type: application/json');
echo json_encode($tracks);
$conn->close();
?>

Create an HTML page
Create an HTML page named "index.html" to display map and trajectory data . Add the following code to "index.html":

<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8">
 <title>出租车轨迹展示</title>
 <style>
     #map {
         width: 100%;
         height: 500px;
     }
 </style>
</head>
<body>
 <div id="map"></div>
 <script src="http://api.map.baidu.com/api?v=2.0&ak=your_api_key"></script>
 <script>
     var map = new BMap.Map("map");
     map.centerAndZoom(new BMap.Point(116.404, 39.915), 14);
     
     // 获取轨迹数据
     var carId = 1; // 假设需要展示的出租车ID为1
     var xhr = new XMLHttpRequest();
     xhr.open("GET", "map.php?car_id=" + carId, true);
     xhr.onreadystatechange = function () {
         if (xhr.readyState === 4 && xhr.status === 200) {
             var tracks = JSON.parse(xhr.responseText);
             // 绘制轨迹
             var path = tracks.map(function (track) {
                 return new BMap.Point(track.lng, track.lat);
             });
             var polyline = new BMap.Polyline(path, {strokeColor: "blue", strokeWeight: 3, strokeOpacity: 0.5});
             map.addOverlay(polyline);
         }
     };
     xhr.send();
 </script>
</body>
</html>

Run the example
Place the "map.php" and "index.html" files on your PHP server by browsing You can see the taxi trajectory display effect by accessing the "index.html" page.

Summary:
This tutorial introduces how to use PHP and Baidu Map API to implement the taxi trajectory display function. By using PHP to obtain trajectory data from the database, and using Baidu Maps' JavaScript API to draw maps and trajectories, we are able to dynamically display the movement trajectory of each taxi. You can further optimize and expand based on actual needs, such as adding taxi markers, real-time trajectory updates and other functions.

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