不显示谷歌地图标记（lat、lng 值和其他信息从 xml 文件加载）

Question

我正在研究这里给出的示例：- https://developers.google.com/maps/documentation/javascript/mysql-to-maps 我在“加载 xml 文件”这一点上。我已将数据库与 php 链接以形成给定数据的 xml 文件（File.xml），但我不知道为什么它不起作用。我尝试了许多其他示例。但无法仅弄清楚“如何加载 xml 文件”部分，因为没有代码工作并且控制台中没有错误。

<script>
              var customLabel = {
            restaurant: {
              label: 'R'
            },
            bar: {
              label: 'B'
            }
          };

        function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
          center: new google.maps.LatLng(-33.863276, 151.207977),
          zoom: 12
        });
        var infoWindow = new google.maps.InfoWindow;

          // Change this depending on the name of your PHP or XML file
          downloadUrl('File.xml', function(data) {
            var xml = data.responseXML;
            var markers = xml.documentElement.getElementsByTagName('marker');
            Array.prototype.forEach.call(markers, function(markerElem) {
              var name = markerElem.getAttribute('name');
              var address = markerElem.getAttribute('address');
              var type = markerElem.getAttribute('type');
              var point = new google.maps.LatLng(
                  parseFloat(markerElem.getAttribute('lat')),
                  parseFloat(markerElem.getAttribute('lng')));

              var infowincontent = document.createElement('div');
              var strong = document.createElement('strong');
              strong.textContent = name
              infowincontent.appendChild(strong);
              infowincontent.appendChild(document.createElement('br'));

              var text = document.createElement('text');
              text.textContent = address
              infowincontent.appendChild(text);
              var icon = customLabel[type] || {};
              var marker = new google.maps.Marker({
                map: map,
                position: point,
                label: icon.label
              });
              marker.addListener('click', function() {
                infoWindow.setContent(infowincontent);
                infoWindow.open(map, marker);
              });
            });
          });
        }



      function downloadUrl(url, callback) {
        var request = window.ActiveXObject ?
            new ActiveXObject('Microsoft.XMLHTTP') :
            new XMLHttpRequest;

        request.onreadystatechange = function() {
          if (request.readyState == 4) {
            request.onreadystatechange = doNothing;
            callback(request, request.status);
          }
        };

        request.open('GET', url, true);
      }

      function doNothing() {}
    </script>

Answer 1

你刚刚忘记复制downloadUrl函数的最后一行：request.send(null);