作者: , 出处:Dev2Dev, 责任编辑: 叶江,
2007-06-13 14:59
本文中将使用工具轻松构建终极的Hello World mashup：Google地图mashup……
客户端将使用XMLHttpRequest 从REST服务检索JSON 对象。一旦检索到该对象，JavaScript 代码将需要反序列化对象，然后遍历整个数组。看一下mapper.js，就可以看到 getLocationsAndMap 和 getLocationsAndMapCallback 函数完成了这一功能：
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// Gets the current locations from the REST service
// on the server and writes out the HTML that
// contains links for the map
function getLocationsAndMap() {
if (receiveReq.readyState == 4 ||
receiveReq.readyState == 0)
{
// getD2DSites.html is a REST service
// that returns the list of locations
// as JSON
receiveReq.open("GET", ‘getD2DSites.html‘,
true);
receiveReq.onreadystatechange =
getLocationsAndMapCallback;
receiveReq.send(null);
} // end if
} // end function
function getLocationsAndMapCallback() {
// state == 4 is when the response is complete
if (receiveReq.readyState == 4) {
// Deserialize the JSON response (eval() command)
// This creates an array of location objects.
var response = eval("("+request.responseText+")");
// generate HTML listing the locations and update
// the page DOM so the user will see the HTML
var div = document.getElementById(‘loc_div‘);
div.innerHTML = ‘<p>Received ‘ +
response.locations.location.length+‘ results.‘;
for(i=0;i < response.locations.location.length; i++) {
var city = response.locations.location[i].city;
var anchor = ‘‘; // TODO: we will fix this later
div.innerHTML += ‘<p><b>‘+ city + ‘</b> ‘ +
anchor + loc + ‘</a><br/>‘ + addr + ‘</p>‘;
} // end for loop
} // end if (state == 4)
} // end function
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请注意， eval 调用将接收JSON 并对它进行计算，有效地构建一个可以导航的JavaScript数组。For 循环显示了如何在数组内遍历地理位置：
至此，您已经完成了这些工作：
- 创建一个静态的 REST 服务 HTML 文件
- 向HTML文件添加一个JSON 有效负载
- 编写代码通过eval()将JSON 重构为一个JavaScript 对象
- 编写代码来循环遍历地址数组，使用新的HTML操纵DOM
现在，让我们来看如何在Google 地图中显示这些位置。
