Openlayers 4 - 加载 WMS 图像层需要身份验证答案

【问题标题】：Openlayers 4 - Load WMS image layer require authenticationOpenlayers 4 - 加载 WMS 图像层需要身份验证
【发布时间】：2018-05-22 15:37:12
【问题描述】：

我尝试用 openlayers 4.6 和 angular 5 加载 WMS 图像层，代码是：

const syr_layer = new ol_layer_Image({
  source: new ol_source_ImageWMS({
      url: 'serverurl', crossOrigin: 'anonymous', serverType: 'geoserver',
      params: { 'LAYERS': 'tst:syr'},
      projection: 'EPSG:4326'
    });
});

但是它会抛出一个错误：

GET (myserverurl) 401（在安全上下文）

如何通过 openlayers 发送的 GET 请求发送身份验证标头？

【问题讨论】：

标签： typescript authentication openlayers wms

【解决方案1】：

感谢@Thomas，您的答案不是 100% 正确，但它为我获得正确答案扫清了道路。

这是对我有用的 tileLoader 函数：

private tileLoader(tile, src) {
  const client = new XMLHttpRequest();

  client.open('GET', src);
  client.responseType = 'arraybuffer';
  client.setRequestHeader('Authorization', 'Basic ' + btoa(user + ':' + pass));

  client.onload = function () {
    const arrayBufferView = new Uint8Array(this.response);
    const blob = new Blob([arrayBufferView], { type: 'image/png' });
    const urlCreator = window.URL || (window as any).webkitURL;
    const imageUrl = urlCreator.createObjectURL(blob);
    tile.getImage().src = imageUrl;
  };

  client.send();
}

【讨论】：

【解决方案2】：

出于您的目的，您可能希望使用来自ol.source.ImageWMS 的tileLoadFunction (API doc)

为了说明，你可以看下面。 2个“秘密”是customLoader，用于身份验证以取消注释req.setRequestHeader("Authorization", "Basic " + window.btoa(user + ":" + pass));

<!DOCTYPE html>
<html>
  <head>
    <title>Tiled WMS</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v4.6.5/css/ol.css" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <script src="https://openlayers.org/en/v4.6.5/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      function customLoader(tile, src) {
        var client = new XMLHttpRequest();
        client.open('GET', src);
        // Uncomment to pass authentication header
        //req.setRequestHeader("Authorization", "Basic " + window.btoa(user + ":" + pass));
        client.onload = function() {
          tile.getImage().src = src;
        };
        client.send();
      }
      var layers = [
        new ol.layer.Tile({
          source: new ol.source.OSM()
        }),
        new ol.layer.Tile({
          extent: [-13884991, 2870341, -7455066, 6338219],
          source: new ol.source.TileWMS({
            url: 'https://ahocevar.com/geoserver/wms',
            tileLoadFunction: customLoader,
            params: {'LAYERS': 'topp:states', 'TILED': true},
            serverType: 'geoserver',
            // Countries have transparency, so do not fade tiles:
            transition: 0
          })
        })
      ];
      var map = new ol.Map({
        layers: layers,
        target: 'map',
        view: new ol.View({
          center: [-10997148, 4569099],
          zoom: 4
        })
      });
    </script>
  </body>
</html>

答案主要是从How to add a http header to openlayers3 requests?借来的，但由于提供的语法不起作用，所以做了一些修改。

【讨论】：