自动重新加载OpenLayers.Layer.Text标记的数据

Question

I am currently trying to layer some markers over a OSM map using OpenLayers. 我目前正在尝试使用OpenLayers在OSM地图上分层一些标记。 The page should refresh in a certain interval and load new data from the DB. 该页面应以一定的间隔刷新，并从数据库加载新数据。

I feed the data from the DB to the OpenLayers.Layer.Text through a local servlet which constructs the input file from the records in the DB. 我通过本地servlet从数据库将数据提供给OpenLayers.Layer.Text，该servlet从数据库中的记录构造输入文件。

My current approach is to simpy use <meta http-equiv="refresh" content="3"> which reloads the page and subsequently the script. 我当前的方法是使用<meta http-equiv="refresh" content="3">进行简单化，这将重新加载页面并随后重新加载脚本。 Problem with this approach is, that the OSM map is reset, ie zoom, view port, etc. 这种方法的问题是OSM映射被重置，即缩放，查看端口等。

I have thus tried to use a refresh strategy from OpenLayers but this does not seem to reload the data from the servlet for the corresponding layer. 因此，我尝试使用OpenLayers的刷新策略，但这似乎并未从servlet的相应层重新加载数据。

<!DOCTYPE html>
<html>
    <head>
        <title>OSM View/title>
        <meta charset="utf-8"/>
        <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
        <!--meta http-equiv="refresh" content="3"-->
    </head>
    <body>
        <div id="mapdiv" style="height:750px"></div>
        <script src="http://www.openlayers.org/api/OpenLayers.js"></script>
        <script>
            var lat = 52;
            var lon = 10;
            var zoom = 18;

            map = new OpenLayers.Map("mapdiv", {
                controls: [
                    new OpenLayers.Control.Navigation(),
                    new OpenLayers.Control.PanZoomBar(),
                    new OpenLayers.Control.LayerSwitcher()
                ],
                projection: 'EPSG:900913',
                displayProjection: 'EPSG:4326',
                numZoomLevels: 18,
                units: 'm'
            });

            mapnik = new OpenLayers.Layer.OSM("Karte");
            map.addLayer(mapnik);

            var marker = new OpenLayers.Layer.Text("marker", {
                location: "http://localhost:8080/marker",
                projection: map.displayProjection,
                strategies: [new OpenLayers.Strategy.Refresh({interval: 3000, force: true})]
            });
            map.addLayer(marker);

            var fromProjection = new OpenLayers.Projection("EPSG:4326"); // Transform from WGS 1984
            var toProjection = new OpenLayers.Projection("EPSG:900913"); // to Spherical Mercator Projection
            var position = new OpenLayers.LonLat(lon, lat).transform(fromProjection, toProjection);

            map.setCenter(position, zoom);
        </script>
    </body>
</html>

Is there a way to achieve what I am trying to do? 有没有办法实现我想做的事情？

Answer 1

OpenLayers.Layer.Text does not support strategies. OpenLayers.Layer.Text不支持策略。

Looking at the code, there isn't any function to reload the data, but you should be able to reload layer data using: 查看代码，没有任何功能可以重新加载数据，但是您应该能够使用以下方法重新加载图层数据：

setInterval(function() {
    layer.clearFeatures();
    layer.loaded = false;
    layer.loadText();
}, 3 * 1000);

自动重新加载OpenLayers.Layer.Text标记的数据

问题描述

1 个解决方案

解决方案1
2 已采纳 2016-12-07 09:04:06

自动重新加载OpenLayers.Layer.Text标记的数据

问题描述

1 个解决方案

解决方案1 2 已采纳 2016-12-07 09:04:06

解决方案1
2 已采纳 2016-12-07 09:04:06