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本教學課程說明如何透過 Firebase 應用程式平台建立互動式地圖。點選下方地圖中的各個地點即可建立熱視圖。
下方是您在本教學課程中建立地圖時所需的完整程式碼。
/**
* Firebase config block.
*/
var config = {
apiKey: 'AIzaSyDX-tgWqPmTme8lqlFn2hIsqwxGL6FYPBY',
authDomain: 'maps-docs-team.firebaseapp.com',
databaseURL: 'https://maps-docs-team.firebaseio.com',
projectId: 'maps-docs-team',
storageBucket: 'maps-docs-team.appspot.com',
messagingSenderId: '285779793579'
};
firebase.initializeApp(config);
/**
* Data object to be written to Firebase.
*/
var data = {sender: null, timestamp: null, lat: null, lng: null};
function makeInfoBox(controlDiv, map) {
// Set CSS for the control border.
var controlUI = document.createElement('div');
controlUI.style.boxShadow = 'rgba(0, 0, 0, 0.298039) 0px 1px 4px -1px';
controlUI.style.backgroundColor = '#fff';
controlUI.style.border = '2px solid #fff';
controlUI.style.borderRadius = '2px';
controlUI.style.marginBottom = '22px';
controlUI.style.marginTop = '10px';
controlUI.style.textAlign = 'center';
controlDiv.appendChild(controlUI);
// Set CSS for the control interior.
var controlText = document.createElement('div');
controlText.style.color = 'rgb(25,25,25)';
controlText.style.fontFamily = 'Roboto,Arial,sans-serif';
controlText.style.fontSize = '100%';
controlText.style.padding = '6px';
controlText.textContent =
'The map shows all clicks made in the last 10 minutes.';
controlUI.appendChild(controlText);
}
/**
* Starting point for running the program. Authenticates the user.
* @param {function()} onAuthSuccess - Called when authentication succeeds.
*/
function initAuthentication(onAuthSuccess) {
firebase.auth().signInAnonymously().catch(function(error) {
console.log(error.code + ', ' + error.message);
}, {remember: 'sessionOnly'});
firebase.auth().onAuthStateChanged(function(user) {
if (user) {
data.sender = user.uid;
onAuthSuccess();
} else {
// User is signed out.
}
});
}
/**
* Creates a map object with a click listener and a heatmap.
*/
function initMap() {
var map = new google.maps.Map(document.getElementById('map'), {
center: {lat: 0, lng: 0},
zoom: 3,
styles: [{
featureType: 'poi',
stylers: [{ visibility: 'off' }] // Turn off POI.
},
{
featureType: 'transit.station',
stylers: [{ visibility: 'off' }] // Turn off bus, train stations etc.
}],
disableDoubleClickZoom: true,
streetViewControl: false,
});
// Create the DIV to hold the control and call the makeInfoBox() constructor
// passing in this DIV.
var infoBoxDiv = document.createElement('div');
makeInfoBox(infoBoxDiv, map);
map.controls[google.maps.ControlPosition.TOP_CENTER].push(infoBoxDiv);
// Listen for clicks and add the location of the click to firebase.
map.addListener('click', function(e) {
data.lat = e.latLng.lat();
data.lng = e.latLng.lng();
addToFirebase(data);
});
// Create a heatmap.
var heatmap = new google.maps.visualization.HeatmapLayer({
data: [],
map: map,
radius: 16
});
initAuthentication(initFirebase.bind(undefined, heatmap));
}
/**
* Set up a Firebase with deletion on clicks older than expiryMs
* @param {!google.maps.visualization.HeatmapLayer} heatmap The heatmap to
*/
function initFirebase(heatmap) {
// 10 minutes before current time.
var startTime = new Date().getTime() - (60 * 10 * 1000);
// Reference to the clicks in Firebase.
var clicks = firebase.database().ref('clicks');
// Listen for clicks and add them to the heatmap.
clicks.orderByChild('timestamp').startAt(startTime).on('child_added',
function(snapshot) {
// Get that click from firebase.
var newPosition = snapshot.val();
var point = new google.maps.LatLng(newPosition.lat, newPosition.lng);
var elapsedMs = Date.now() - newPosition.timestamp;
// Add the point to the heatmap.
heatmap.getData().push(point);
// Request entries older than expiry time (10 minutes).
var expiryMs = Math.max(60 * 10 * 1000 - elapsedMs, 0);
// Set client timeout to remove the point after a certain time.
window.setTimeout(function() {
// Delete the old point from the database.
snapshot.ref.remove();
}, expiryMs);
}
);
// Remove old data from the heatmap when a point is removed from firebase.
clicks.on('child_removed', function(snapshot, prevChildKey) {
var heatmapData = heatmap.getData();
var i = 0;
while (snapshot.val().lat != heatmapData.getAt(i).lat()
|| snapshot.val().lng != heatmapData.getAt(i).lng()) {
i++;
}
heatmapData.removeAt(i);
});
}
/**
* Updates the last_message/ path with the current timestamp.
* @param {function(Date)} addClick After the last message timestamp has been updated,
* this function is called with the current timestamp to add the
* click to the firebase.
*/
function getTimestamp(addClick) {
// Reference to location for saving the last click time.
var ref = firebase.database().ref('last_message/' + data.sender);
ref.onDisconnect().remove(); // Delete reference from firebase on disconnect.
// Set value to timestamp.
ref.set(firebase.database.ServerValue.TIMESTAMP, function(err) {
if (err) { // Write to last message was unsuccessful.
console.log(err);
} else { // Write to last message was successful.
ref.once('value', function(snap) {
addClick(snap.val()); // Add click with same timestamp.
}, function(err) {
console.warn(err);
});
}
});
}
/**
* Adds a click to firebase.
* @param {Object} data The data to be added to firebase.
* It contains the lat, lng, sender and timestamp.
*/
function addToFirebase(data) {
getTimestamp(function(timestamp) {
// Add the new timestamp to the record data.
data.timestamp = timestamp;
var ref = firebase.database().ref('clicks').push(data, function(err) {
if (err) { // Data was not written to firebase.
console.warn(err);
}
});
});
}<div id="map"></div>
/* Always set the map height explicitly to define the size of the div
* element that contains the map. */
#map {
height: 100%;
}
/* Optional: Makes the sample page fill the window. */
html, body {
height: 100%;
margin: 0;
padding: 0;
}<!-- Replace the value of the key parameter with your own API key. --> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&libraries=visualization&callback=initMap" defer></script> <script src="https://www.gstatic.com/firebasejs/5.3.0/firebase.js"></script>
親自試試
您可以按一下程式碼視窗右上角的 <> 圖示，在 JSFiddle 中測試這個程式碼。
<!DOCTYPE html>
<html>
<head>
<style>
/* Always set the map height explicitly to define the size of the div
* element that contains the map. */
#map {
height: 100%;
}
/* Optional: Makes the sample page fill the window. */
html, body {
height: 100%;
margin: 0;
padding: 0;
}
</style>
</head>
<body>
<div id="map"></div>
<script src="https://www.gstatic.com/firebasejs/5.3.0/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/5.3.0/firebase-auth.js"></script>
<script src="https://www.gstatic.com/firebasejs/5.3.0/firebase-database.js"></script>
<script>
/**
* Firebase config block.
*/
var config = {
apiKey: 'AIzaSyDX-tgWqPmTme8lqlFn2hIsqwxGL6FYPBY',
authDomain: 'maps-docs-team.firebaseapp.com',
databaseURL: 'https://maps-docs-team.firebaseio.com',
projectId: 'maps-docs-team',
storageBucket: 'maps-docs-team.appspot.com',
messagingSenderId: '285779793579'
};
firebase.initializeApp(config);
/**
* Data object to be written to Firebase.
*/
var data = {sender: null, timestamp: null, lat: null, lng: null};
function makeInfoBox(controlDiv, map) {
// Set CSS for the control border.
var controlUI = document.createElement('div');
controlUI.style.boxShadow = 'rgba(0, 0, 0, 0.298039) 0px 1px 4px -1px';
controlUI.style.backgroundColor = '#fff';
controlUI.style.border = '2px solid #fff';
controlUI.style.borderRadius = '2px';
controlUI.style.marginBottom = '22px';
controlUI.style.marginTop = '10px';
controlUI.style.textAlign = 'center';
controlDiv.appendChild(controlUI);
// Set CSS for the control interior.
var controlText = document.createElement('div');
controlText.style.color = 'rgb(25,25,25)';
controlText.style.fontFamily = 'Roboto,Arial,sans-serif';
controlText.style.fontSize = '100%';
controlText.style.padding = '6px';
controlText.textContent =
'The map shows all clicks made in the last 10 minutes.';
controlUI.appendChild(controlText);
}
/**
* Starting point for running the program. Authenticates the user.
* @param {function()} onAuthSuccess - Called when authentication succeeds.
*/
function initAuthentication(onAuthSuccess) {
firebase.auth().signInAnonymously().catch(function(error) {
console.log(error.code + ', ' + error.message);
}, {remember: 'sessionOnly'});
firebase.auth().onAuthStateChanged(function(user) {
if (user) {
data.sender = user.uid;
onAuthSuccess();
} else {
// User is signed out.
}
});
}
/**
* Creates a map object with a click listener and a heatmap.
*/
function initMap() {
var map = new google.maps.Map(document.getElementById('map'), {
center: {lat: 0, lng: 0},
zoom: 3,
styles: [{
featureType: 'poi',
stylers: [{ visibility: 'off' }] // Turn off POI.
},
{
featureType: 'transit.station',
stylers: [{ visibility: 'off' }] // Turn off bus, train stations etc.
}],
disableDoubleClickZoom: true,
streetViewControl: false,
});
// Create the DIV to hold the control and call the makeInfoBox() constructor
// passing in this DIV.
var infoBoxDiv = document.createElement('div');
makeInfoBox(infoBoxDiv, map);
map.controls[google.maps.ControlPosition.TOP_CENTER].push(infoBoxDiv);
// Listen for clicks and add the location of the click to firebase.
map.addListener('click', function(e) {
data.lat = e.latLng.lat();
data.lng = e.latLng.lng();
addToFirebase(data);
});
// Create a heatmap.
var heatmap = new google.maps.visualization.HeatmapLayer({
data: [],
map: map,
radius: 16
});
initAuthentication(initFirebase.bind(undefined, heatmap));
}
/**
* Set up a Firebase with deletion on clicks older than expiryMs
* @param {!google.maps.visualization.HeatmapLayer} heatmap The heatmap to
*/
function initFirebase(heatmap) {
// 10 minutes before current time.
var startTime = new Date().getTime() - (60 * 10 * 1000);
// Reference to the clicks in Firebase.
var clicks = firebase.database().ref('clicks');
// Listen for clicks and add them to the heatmap.
clicks.orderByChild('timestamp').startAt(startTime).on('child_added',
function(snapshot) {
// Get that click from firebase.
var newPosition = snapshot.val();
var point = new google.maps.LatLng(newPosition.lat, newPosition.lng);
var elapsedMs = Date.now() - newPosition.timestamp;
// Add the point to the heatmap.
heatmap.getData().push(point);
// Request entries older than expiry time (10 minutes).
var expiryMs = Math.max(60 * 10 * 1000 - elapsedMs, 0);
// Set client timeout to remove the point after a certain time.
window.setTimeout(function() {
// Delete the old point from the database.
snapshot.ref.remove();
}, expiryMs);
}
);
// Remove old data from the heatmap when a point is removed from firebase.
clicks.on('child_removed', function(snapshot, prevChildKey) {
var heatmapData = heatmap.getData();
var i = 0;
while (snapshot.val().lat != heatmapData.getAt(i).lat()
|| snapshot.val().lng != heatmapData.getAt(i).lng()) {
i++;
}
heatmapData.removeAt(i);
});
}
/**
* Updates the last_message/ path with the current timestamp.
* @param {function(Date)} addClick After the last message timestamp has been updated,
* this function is called with the current timestamp to add the
* click to the firebase.
*/
function getTimestamp(addClick) {
// Reference to location for saving the last click time.
var ref = firebase.database().ref('last_message/' + data.sender);
ref.onDisconnect().remove(); // Delete reference from firebase on disconnect.
// Set value to timestamp.
ref.set(firebase.database.ServerValue.TIMESTAMP, function(err) {
if (err) { // Write to last message was unsuccessful.
console.log(err);
} else { // Write to last message was successful.
ref.once('value', function(snap) {
addClick(snap.val()); // Add click with same timestamp.
}, function(err) {
console.warn(err);
});
}
});
}
/**
* Adds a click to firebase.
* @param {Object} data The data to be added to firebase.
* It contains the lat, lng, sender and timestamp.
*/
function addToFirebase(data) {
getTimestamp(function(timestamp) {
// Add the new timestamp to the record data.
data.timestamp = timestamp;
var ref = firebase.database().ref('clicks').push(data, function(err) {
if (err) { // Data was not written to firebase.
console.warn(err);
}
});
});
}
</script>
<script defer
src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=visualization&callback=initMap">
</script>
</body>
</html>開始使用
您可以使用本教學課程中的程式碼，開發自有版本的 Firebase 地圖。如要開始著手，請在文字編輯器中建立新檔案，並將檔案儲存為 index.html。
請閱讀後續章節，瞭解可以加到這個檔案中的程式碼。
建立基本地圖
這個部分說明設定基本地圖的程式碼。這可能與您在開始使用 Maps JavaScript API 時建立地圖的方式類似。
請將以下程式碼複製到 index.html 檔案中。這個程式碼會載入 Maps JavaScript API，並以全螢幕顯示地圖。也會載入視覺化程式庫，供您稍後在教學課程中用來建立熱視圖。
<!DOCTYPE html>
<html>
<head>
<style>
#map {
height: 100%;
}
html, body {
height: 100%;
margin: 0;
padding: 0;
}
</style>
</head>
<body>
<div id="map"></div>
<script defer
src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY
&libraries=visualization&callback=initMap">
</script>
<script>
// The JavaScript code that creates the Firebase map goes here.
</script>
</body>
</html>
在程式碼範例中按一下 YOUR_API_KEY，或是按照操作說明取得 API 金鑰。請將 YOUR_API_KEY 替換成應用程式的 API 金鑰。
以下各節說明建立 Firebase 地圖的 JavaScript 程式碼。您可以複製程式碼並儲存在 firebasemap.js 檔案中，以便在指令碼標記之間參照，如下所示。
<script>firebasemap.js</script>
或者，您也可以直接在指令碼標記中插入程式碼，如同本教學課程開頭的完整程式碼範例中所示。
請在 firebasemap.js 檔案中加入下方程式碼，或是 index.html 檔案的空白指令碼標記之間。這是執行程式的起點，其中先建立初始化地圖物件的函式。
function initMap() { var map = new google.maps.Map(document.getElementById('map'), { center: {lat: 0, lng: 0}, zoom: 3, styles: [{ featureType: 'poi', stylers: [{ visibility: 'off' }] // Turn off points of interest. }, { featureType: 'transit.station', stylers: [{ visibility: 'off' }] // Turn off bus stations, train stations, etc. }], disableDoubleClickZoom: true, streetViewControl: false }); }
為了讓這份可點選的熱視圖便於使用，上述程式碼會使用地圖樣式來停用搜尋點和轉運站 (點選時會顯示資訊視窗)，也會停用按兩下縮放功能，避免意外縮放。進一步瞭解如何設定地圖樣式。
API 載入完畢後，以下指令碼標記中的回呼參數會在 HTML 檔案中執行 initMap() 函式。
<script defer
src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY
&libraries=visualization&callback=initMap">
</script>加入下方程式碼，即可在地圖頂端建立文字控制項。
function makeInfoBox(controlDiv, map) { // Set CSS for the control border. var controlUI = document.createElement('div'); controlUI.style.boxShadow = 'rgba(0, 0, 0, 0.298039) 0px 1px 4px -1px'; controlUI.style.backgroundColor = '#fff'; controlUI.style.border = '2px solid #fff'; controlUI.style.borderRadius = '2px'; controlUI.style.marginBottom = '22px'; controlUI.style.marginTop = '10px'; controlUI.style.textAlign = 'center'; controlDiv.appendChild(controlUI); // Set CSS for the control interior. var controlText = document.createElement('div'); controlText.style.color = 'rgb(25,25,25)'; controlText.style.fontFamily = 'Roboto,Arial,sans-serif'; controlText.style.fontSize = '100%'; controlText.style.padding = '6px'; controlText.innerText = 'The map shows all clicks made in the last 10 minutes.'; controlUI.appendChild(controlText); }
在 initMap 函式中的 var map 後方加入下方程式碼，即可載入文字控制方塊。
// Create the DIV to hold the control and call the makeInfoBox() constructor // passing in this DIV. var infoBoxDiv = document.createElement('div'); var infoBox = new makeInfoBox(infoBoxDiv, map); infoBoxDiv.index = 1; map.controls[google.maps.ControlPosition.TOP_CENTER].push(infoBoxDiv);
如要查看程式碼所建立的 Google 地圖，請在網路瀏覽器中開啟 index.html 檔案。
設定 Firebase
為了讓這個應用程式可以進行協作，您必須將點擊資料儲存在所有使用者皆可存取的外部資料庫中。Firebase 即時資料庫可滿足這個用途，且您不需要對 SQL 有任何瞭解。
請先註冊 Firebase 帳戶 (免付費)。如果您是 Firebase 新手，系統會顯示名為「My First App」(我的第一個應用程式) 的新應用程式。如果您建立新應用程式，可以設定新名稱並自訂 Firebase 網址 (結尾為 firebaseIO.com)。例如，您可以將應用程式命名為「阿珍的 Firebase 地圖」，網址為 https://janes-firebase-map.firebaseIO.com。您可以使用這個網址將資料庫連結至 JavaScript 應用程式。
在 HTML 檔案的 <head> 標記後方加入下方程式碼，即可匯入 Firebase 程式庫。
<script src="www.gstatic.com/firebasejs/5.3.0/firebase.js"></script>
在您的 JavaScript 檔案中加入下方程式碼：
var firebase = new Firebase("<Your Firebase URL here>");
在 Firebase 中儲存點擊資料
這個部分說明的程式碼可用來在 Firebase 中儲存與地圖上滑鼠點擊相關的資料。
每次地圖上發生滑鼠點擊時，下方程式碼都會建立全域資料物件，並將相關資訊儲存在 Firebase 中。這個物件會記錄 latLng 和點擊時間戳記等資料，以及發生點擊的瀏覽器專屬 ID。
/** * Data object to be written to Firebase. */ var data = { sender: null, timestamp: null, lat: null, lng: null };
以下程式碼會針對每次點擊記錄不重複的工作階段 ID，這有助於按照 Firebase 安全性規則控管地圖上的流量率。
/** * Starting point for running the program. Authenticates the user. * @param {function()} onAuthSuccess - Called when authentication succeeds. */ function initAuthentication(onAuthSuccess) { firebase.auth().signInAnonymously().catch(function(error) { console.log(error.code + ", " + error.message); }, {remember: 'sessionOnly'}); firebase.auth().onAuthStateChanged(function(user) { if (user) { data.sender = user.uid; onAuthSuccess(); } else { // User is signed out. } }); }
下一部分的程式碼會監聽地圖上的點擊，這會在您的 Firebase 資料庫中加入「子項」。發生這種情況時，snapshot.val() 函式會取得項目的資料值，並建立新的 LatLng 物件。
// Listen for clicks and add them to the heatmap. clicks.orderByChild('timestamp').startAt(startTime).on('child_added', function(snapshot) { var newPosition = snapshot.val(); var point = new google.maps.LatLng(newPosition.lat, newPosition.lng); heatmap.getData().push(point); } );
下列程式碼會將 Firebase 設為：
- 監聽地圖上的點擊。發生點擊時，應用程式會記錄時間戳記，然後在 Firebase 資料庫中新增「子項」。
- 即時刪除地圖上超過 10 分鐘的任何點擊。
/** * Set up a Firebase with deletion on clicks older than expirySeconds * @param {!google.maps.visualization.HeatmapLayer} heatmap The heatmap to * which points are added from Firebase. */ function initFirebase(heatmap) { // 10 minutes before current time. var startTime = new Date().getTime() - (60 * 10 * 1000); // Reference to the clicks in Firebase. var clicks = firebase.database().ref('clicks'); // Listen for clicks and add them to the heatmap. clicks.orderByChild('timestamp').startAt(startTime).on('child_added', function(snapshot) { // Get that click from firebase. var newPosition = snapshot.val(); var point = new google.maps.LatLng(newPosition.lat, newPosition.lng); var elapsedMs = Date.now() - newPosition.timestamp; // Add the point to the heatmap. heatmap.getData().push(point); // Request entries older than expiry time (10 minutes). var expiryMs = Math.max(60 * 10 * 1000 - elapsed, 0); // Set client timeout to remove the point after a certain time. window.setTimeout(function() { // Delete the old point from the database. snapshot.ref.remove(); }, expiryMs); } ); // Remove old data from the heatmap when a point is removed from firebase. clicks.on('child_removed', function(snapshot, prevChildKey) { var heatmapData = heatmap.getData(); var i = 0; while (snapshot.val().lat != heatmapData.getAt(i).lat() || snapshot.val().lng != heatmapData.getAt(i).lng()) { i++; } heatmapData.removeAt(i); }); }
請將這個部分的所有 JavaScript 程式碼複製到 firebasemap.js 檔案中。
建立熱視圖
下一步是顯示熱視圖，讓檢視者以圖解方式查看地圖上各個地點的相對點擊次數。詳情請參閱熱視圖指南。
在 initMap() 函式中加入下方程式碼，即可建立熱視圖。
// Create a heatmap. var heatmap = new google.maps.visualization.HeatmapLayer({ data: [], map: map, radius: 16 });
以下程式碼會觸發 initFirebase、addToFirebase 和 getTimestamp 函式。
initAuthentication(initFirebase.bind(undefined, heatmap));
請注意，如果您點選熱視圖，目前還無法建立資料點。如要在地圖上建立資料點，您必須設定地圖事件監聽器。
在熱視圖上建立資料點
以下程式碼會在 initMap() 內建立地圖的程式碼後方新增事件監聽器。這個程式碼會監聽每次點擊的資料，將點擊位置儲存在 Firebase 資料庫中，並在熱視圖中顯示資料點。
// Listen for clicks and add the location of the click to firebase. map.addListener('click', function(e) { data.lat = e.latLng.lat(); data.lng = e.latLng.lng(); addToFirebase(data); });
在地圖上按一下地點，即可在熱視圖上建立資料點。
現在，您已經使用 Firebase 和 Maps JavaScript API，建立功能完整的即時應用程式。
點擊熱視圖後，點擊的經緯度現在應會顯示在 Firebase 資料庫中。如要查看這項資訊，請登入 Firebase 帳戶，然後前往應用程式的資料分頁。此時，如果其他使用者點擊您的地圖，您和對方都能在地圖上看到資料點。即使使用者關閉網頁，點擊位置仍會保持不變。如要測試即時協作功能，請在兩個不同的視窗中分別開啟頁面，標記應該會即時顯示在兩個視窗中。
瞭解詳情
Firebase 是應用程式平台，以 JSON 格式儲存資料，並即時同步至所有已連結的用戶端，而且即使應用程式離線也能使用。本教學課程使用該平台的即時資料庫。