简明现代魔法 -> 软件项目 -> Google Maps 地理编码缓存

Google Maps 地理编码缓存

2010-01-11

// Builds an array of geocode responses for the 5 cities.
	var city = [
    {
		name: "Washington, DC",
      	Status: 
		{
        code: 200,
        request: "geocode"
      	},
      	Placemark: 
		[
        {
          	address: "Washington, DC, USA",
          	population: "0.563M",
          	Point: 
		  	{
            	coordinates: [-77.036667, 38.895000, 0]
          	},
         	 AddressDetails: 
		  	{
            	Country: 
				{
              		CountryNameCode: "US",
              		AdministrativeArea: 
					{
              			AdministrativeAreaName: "DC",
                		Locality: {LocalityName: "Washington"}
              		}
            	}
          	}
     	}
      	]
	},
    {
      	name: "Tokyo, Japan",
      	Status: 
		{
        	code: 200,
        	request: "geocode"
      	},
      	Placemark: 
		[
        {
          	address: "Tokyo, Japan",
          	population: "12.527M",
          	Point: 
			{
            	coordinates: [139.770004, 35.669998, 0]
          	},
            AddressDetails: 
			{
            	Country: 
				{
              		CountryNameCode: "US",
              		AdministrativeArea: 
					{
                		AdministrativeAreaName: "CA",
                		Locality: {LocalityName: "Los Angeles"}
              		}
            	}
          	}
       	}
      	]
    },
    {
      	name: "Paris, France",
      	Status: 
		{
        	code: 200,
        	request: "geocode"
      	},
      	Placemark: 
		[
        {
          	address: "Paris, France",
          	population: "2.144M",
          	Point: 
			{
            	coordinates: [2.351019, 48.856662, 0]
          	},
          	AddressDetails: 
			{
            	Country: 
				{
              		CountryNameCode: "FR",
              		Locality: {LocalityName: "Paris"}
            	}
          	}
        }
      	]
    },
    {
      	name: "Rome, Italy",
      	Status: 
		{
        	code: 200,
        	request: "geocode"
      	},
      	Placemark: 
		[
        {
          	address: "Rome, Italy",
          	population: "2.553M",
          	Point: 
			{
            	coordinates: [12.482181, 41.895431, 0]
          	},
          	AddressDetails: 
			{
            	Country: 
				{
              		CountryNameCode: "IT",
              		Locality: {LocalityName: "Roma"}
            	}
          	}
        }
      	]
    },
    {
      	name: "Berlin, Germany",
      	Status: 
		{
        	code: 200,
        	request: "geocode"
      	},
      	Placemark: 
		[
        {
          	address: "Berlin, Germany",
          	population: "3.396M",
          	Point: 
			{
            	coordinates: [13.411895, 52.523781, 0]
          	},
          	AddressDetails: 
			{
            	Country: 
				{
              		CountryNameCode: "DE",
              		Locality: {LocalityName: "Berlin"}
            	}
          	}
        }
      	]
    },
    {
      	name: "Madrid, Spain",
      	Status: 
		{
        	code: 200,
        	request: "geocode"
      	},
      	Placemark: 
		[
        {
          	address: "Madrid, Spain",
          	population: "3.228M",
          	Point: 
			{
            	coordinates: [-3.703270, 40.416712, 0]
          	},
          	AddressDetails: 
			{
            	Country: 
				{
              		CountryNameCode: "ES",
              		Locality: {LocalityName: "Madrid"}
            	}
          	}
        }
      	]
    }
  	];

  	var map;
  	var geocoder;

// CapitalCitiesCache is a custom cache that extends the standard GeocodeCache.
// We call apply(this) to invoke the parent's class constructor.
function CapitalCitiesCache() 
{
	GGeocodeCache.apply(this);
}

// Assigns an instance of the parent class as a prototype of the
// child class, to make sure that all methods defined on the parent
// class can be directly invoked on the child class.
CapitalCitiesCache.prototype = new GGeocodeCache();

// Override the reset method to populate the empty cache with
// information from our array of geocode responses for capitals.
CapitalCitiesCache.prototype.reset = function() 
{
    GGeocodeCache.prototype.reset.call(this);
    for (var i in city) 
	{
      	this.put(city[i].name, city[i]);
    }
}

function initialize() 
{
    map = new GMap2(document.getElementById("map_canvas"));
    map.setCenter(new GLatLng(37.441944, -122.141944), 6);
    geocoder = new GClientGeocoder();
    geocoder.setCache(new CapitalCitiesCache());
}

function findCity(which) 
{
    if (which != 0) 
	{
      	geocoder.getLocations(city[which - 1].name, addAddressToMap);
    }
}  

还有一个函数，另外标出来。

function addAddressToMap(response) 
{
    map.clearOverlays();

    if (response && response.Status.code != 200) 
	{
      	alert("Unable to locate " + decodeURIComponent(response.name));
    } 
	else 
	{
      	var place = response.Placemark[0];
      	var point = new GLatLng(place.Point.coordinates[1],
                              	place.Point.coordinates[0]);
      	map.setCenter(point, 6);
      	map.openInfoWindowHtml(point, "<b>City:</b> " + place.address
       		+ "<br><b>Population:</b> " + place.population);
    }
}

查看示例