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Openlayers2加载百度地图

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可以完成加载百度地图，但使用纠偏后的坐标定位有偏移。将下面连接的代码做了部分修改。 [转]http://www.cnblogs.com/songjiang6940/p/4139258.html

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OpenLayers.Layer.Baidu = OpenLayers.Class(OpenLayers.Layer.TileCache, {
    initialize: function (name, url, options) {
        var tempoptions = OpenLayers.Util.extend({
        'format': 'image/png',
        isBaseLayer: true
        }, options);
        OpenLayers.Layer.TileCache.prototype.initialize.apply(this, [name, url, {},
        tempoptions]);
        this.extension = this.format.split('/')[1].toLowerCase();
        this.extension = (this.extension == 'jpg') ? 'jpeg' : this.extension;
        this.transitionEffect = "resize";
        this.buffer = 0;
    },
    /**
    * 按地图引擎切图规则实现的拼接方式
    */
    getURL: function (bounds) {
        var tilez=this.map.zoom-1;
        var res = this.map.getResolution();
        var bbox = this.map.getMaxExtent();
        var size = this.tileSize;
        var bx = Math.round((bounds.left - this.tileOrigin.lon) / (res * size.w));
        var by = Math.round((bounds.bottom - this.tileOrigin.lat) / (res * size.h));
        tilez = tilez + 1;
        var x = bx.toString().replace("-","M");
        var y = by.toString().replace("-","M");
        var urlsNum = parseInt((bx + by) % this.url.length);
        var strURL = "";
        strURL = this.url[urlsNum] + '?qt=tile&x='+x+'&y='+y+'&z='+tilez+'&styles=pl&udt=20140807';
        return strURL;
    },
    clone: function (obj) {
        if (obj == null) {
            obj = new OpenLayers.Layer.Baidu(this.name, this.url, this.options);
        }
        obj = OpenLayers.Layer.TileCache.prototype.clone.apply(this, [obj]);
        return obj;
    },
    CLASS_NAME: "OpenLayers.Layer.Baidu"
});
 
/**
 * 墨卡托投影坐标转换为经纬度坐标
 */
function meterXY2GeoLoc(x, y, precision){
    var earthCircumferenceInMeters = new Number(40075016.685578488);
    var halfEarthCircumferenceInMeters = earthCircumferenceInMeters / 2;
 
    var geoX = x/halfEarthCircumferenceInMeters*180;
    var geoY = y/halfEarthCircumferenceInMeters*180;
    geoY = Math.atan(Math.exp(geoY * (Math.PI / 180.0)))*360.0/Math.PI - 90;
 
    geoX = setPrecision(geoX, precision);
    geoY = setPrecision(geoY, precision);
 
    var obj = new Object();
    obj.lngX = geoX;
    obj.latY = geoY;
    return obj;
}
 
/**
 * 经纬度坐标转墨卡托投影坐标
 */
function geoLoc2MeterXY(x, y){
    var earthCircumferenceInMeters = new Number(40075016.685578488);
    var halfEarthCircumferenceInMeters = earthCircumferenceInMeters / 2;
 
    var geoX = new Number(x);
    var geoY = new Number(y);
 
    var mx = geoX / 180.0 * halfEarthCircumferenceInMeters;
    var my = Math.log(Math.tan((90 + geoY) * Math.PI / 360.0)) / (Math.PI / 180.0);
    my = my / 180.0 * halfEarthCircumferenceInMeters;
 
    var obj = new Object();
    obj.lngX = mx;
    obj.latY = my;
    return obj;
}
//这个参数在对接中还是稍微有y轴的偏移，考虑因该是百度平面坐标系不是基于web墨卡托投影，而这个用的是web墨卡托投影的方式却对接的。
var tileOrigin = new OpenLayers.LonLat(0,28000);
//var tileOrigin = new OpenLayers.LonLat(-120,22000);
var maxExtent = new OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34);
var opts = {numZoomLevels:20,maxResolution:262144,maxExtent :maxExtent ,tileOrigin :tileOrigin }
 
var baidu = new OpenLayers.Layer.Baidu ('baidu',["http://online1.map.bdimg.com/tile/"],opts);
var map = new OpenLayers.Map("map",{projection:"EPSG:900913",displayProjection:"EPSG:4326"});
 
map.addLayers([baidu]);
//成都-天府广场//baidu:104.072593, 30.663547,GPS:104.0636,30.6599,google:104.066109, 30.657483
//北京-天安门拱桥//baidu:116.40392 ,39.914552,GPS:116.3913,39.9068,google:116.397547, 39.908208
var center=geoLoc2MeterXY(104.072593, 30.663547);
//北京
map.setCenter(new OpenLayers.LonLat(12958399.4681885, 4852082.44060595),10);
//map.setCenter(new OpenLayers.LonLat(center.lngX, center.latY),18);

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