Fetching data with Ajax小例子

ajax获取数据示例:

示例1

通过ajax获取txt文件里面的内容示例：

<html>

<head>

var XMLHttpRequestObject = false;

if (window.XMLHttpRequest) {

XMLHttpRequestObject = new XMLHttpRequest();

} else if (window.ActiveXObject) {

XMLHttpRequestObject = new ActiveXObject("Microsoft.XMLHTTP");

}

function getData(dataSource, divID) {

if(XMLHttpRequestObject) {

var obj = document.getElementById(divID);

XMLHttpRequestObject.open("GET", dataSource);

XMLHttpRequestObject.onreadystatechange = function() {

if (XMLHttpRequestObject.readyState == 4 && XMLHttpRequestObject.status == 200) {

obj.innerHTML = XMLHttpRequestObject.responseText;

}

XMLHttpRequestObject.send(null);

}

</script>

</head>

<body>

<H1>Fetching data with Ajax</H1>

<form>

</form>

<div id="targetDiv"> <p>Welcome to my restaurant!</p> </div>

<div id="targetDiv1"> <p>Welcome to my restaurant!</p> </div>

<div id="targetDiv2"> <p>Welcome to my restaurant!</p> </div>

</body>

</html>

示例2

通过ajax获取XML文件里面的内容示例：

innerHTML.html文件代码：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Using responseText with innerHTML</title>
<script type="text/javascript">
var xmlHttp;
function createXMLHttpRequest() {
    if (window.ActiveXObject) {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();
    }
}
function startRequest() {
    createXMLHttpRequest();
    xmlHttp.onreadystatechange = handleStateChange;
    xmlHttp.open("GET", "innerHTML.xml", true);
    xmlHttp.send(null);
}
function handleStateChange() {
    if(xmlHttp.readyState == 4) {
        if(xmlHttp.status == 200) {
            document.getElementById("results").innerHTML = xmlHttp.responseText;
        }
    }
}
</script>
</head>
<body>
    <form action="#" >
    <input type="button" value="Search for Today's Activities" onClick="startRequest()" />
    </form>
    <div id="results"></div>
</body>
</html>

innerHTML.xml文件代码：

<?xml version="1.0" encoding="UTF-8"?>

<table border="1">
    <tbody>
        <tr>
            <th>Activity Name</th>
            <th>Location</th>
            <th>Time</th>
        </tr>
        <tr>
            <td>Waterskiing</td>
            <td>Dock #1</td>
            <td>9:00 AM</td>
        </tr>
        <tr>
            <td>Volleyball</td>
            <td>East Court</td>
            <td>2:00 PM</td>
        </tr>
        <tr>
            <td>Hiking</td>
            <td>Trail 3</td>
            <td>3:30 PM</td>
        </tr>
    </tbody>
</table>

运行效果：

示例3

通过ajax解析xml数据

parseXML.html文件里面的代码：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html >
<head>
<title>Parsing XML Responses with the W3C DOM</title>

<script type="text/javascript">
var xmlHttp;
var requestType = "";
function createXMLHttpRequest() {
    if (window.ActiveXObject) {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();
    }
}
function startRequest(requestedList) {
    requestType = requestedList;
    createXMLHttpRequest();
    xmlHttp.onreadystatechange = handleStateChange;
    xmlHttp.open("GET", "parseXML.xml", true);
    xmlHttp.send(null);
}
function handleStateChange() {
    if(xmlHttp.readyState == 4) {
        if(xmlHttp.status == 200) {
            if(requestType == "north") {
                listNorthStates();
            }
            else if(requestType == "all") {
                listAllStates();
            }
        }
    }
}
function listNorthStates() {
    var xmlDoc = xmlHttp.responseXML;
    var northNode = xmlDoc.getElementsByTagName("north")[0];
    var northStates = northNode.getElementsByTagName("state");
    outputList("Northern States", northStates);
}
function listAllStates() {
    var xmlDoc = xmlHttp.responseXML;
    var allStates = xmlDoc.getElementsByTagName("state");

    outputList("All States in Document", allStates);
}
function outputList(title, states) {
    var out = title;
    var currentState = null;
    for(var i = 0; i < states.length; i++) {
        currentState = states[i];
        out = out + " - " + currentState.childNodes[0].nodeValue;
    }
    alert(out);
}
</script>
</head>
<body>
    <h1>Process XML Document of U.S. States</h1>
    <br/><br/>
    <form action="#">
        <input type="button" value="View All Listed States" onclick="startRequest('all');"/>
        <br/><br/>
        <input type="button" value="View All Listed Northern States" onclick="startRequest('north');"/>
    </form>
</body>
</html>

parseXML.xml文件里面的代码：

<?xml version="1.0" encoding="UTF-8"?>
<states>
    <north>
        <state>Minnesota</state>
        <state>Iowa</state>
        <state>North Dakota</state>
    </north>
    <south>
        <state>Texas</state>
        <state>Oklahoma</state>
        <state>Louisiana</state>
    </south>
    <east>
        <state>New York</state>
        <state>North Carolina</state>
        <state>Massachusetts</state>
    </east>
    <west>
        <state>California</state>
        <state>Oregon</state>
        <state>Nevada</state>
    </west>
</states>

运行效果如图所示：

示例4

动态更新显示内容：

dynamicContent.html主要代码如下：

createXMLHttpRequest(){

获取XMLHttpRequest代码……

}

function doSearch() {

createXMLHttpRequest();

xmlHttp.onreadystatechange = handleStateChange;

xmlHttp.open("GET", "dynamicContent.xml", true);

xmlHttp.send(null);

}

function handleStateChange() {

if(xmlHttp.readyState == 4) {

if(xmlHttp.status == 200) {

clearPreviousResults();

parseResults();

} } }

function clearPreviousResults() {

var header = document.getElementById("header");

if(header.hasChildNodes()) {

header.removeChild(header.childNodes[0]);

}

var tableBody = document.getElementById("resultsBody");

while(tableBody.childNodes.length > 0) {

tableBody.removeChild(tableBody.childNodes[0]); } }

function parseResults() {

var results = xmlHttp.responseXML;

var property = null; var address = ""; var price = ""; var comments = "";

var min=document.getElementsByName("min");

var max=document.getElementsByName("max");

var minval=min[0].options[min[0].selectedIndex].value; // 选中值

var maxval=max[0].options[max[0].selectedIndex].value; // 选中值

minval=parseFloat(minval); maxval=parseFloat(maxval);

var properties = results.getElementsByTagName("property");

for(var i = 0; i < properties.length; i++) {

property = properties[i];

address = property.getElementsByTagName("address")[0].firstChild.nodeValue;

price = property.getElementsByTagName("price")[0].firstChild.nodeValue;

comments = property.getElementsByTagName("comments")[0].firstChild.nodeValue;

price=parseFloat(price);

if(price>=minval && price<=maxval){

addTableRow(address, price, comments);

};

}

var header = document.createElement("h2");

var headerText = document.createTextNode("Results:");

header.appendChild(headerText);

document.getElementById("header").appendChild(header);

document.getElementById("resultsTable").setAttribute("border", "1"); }

function addTableRow(address, price, comments) {

var row = document.createElement("tr");

var cell = createCellWithText(address);

row.appendChild(cell);

cell = createCellWithText(price);

row.appendChild(cell);

cell = createCellWithText(comments);

row.appendChild(cell);

document.getElementById("resultsBody").appendChild(row);

}

function createCellWithText(text) {

var cell = document.createElement("td");

var textNode = document.createTextNode("$"+text);

cell.appendChild(textNode);

return cell; }

</script>

</head>

<body>

<h1>Search Real Estate Listings</h1>

Show listings from

</select >

</select>

</form>

</body>

</html>

dynamicContent.xml代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<properties>
<property>
        <address>812 Gwyn Ave</address>
        <price>90000</price>
        <comments>Quiet, serene neighborhood</comments>
    </property>
    <property>
        <address>812 Gwyn Ave</address>
        <price>100000</price>
        <comments>Quiet, serene neighborhood</comments>
    </property>
    <property>
        <address>3308 James Ave S</address>
        <price>110000</price>
        <comments>Close to schools, shopping, entertainment</comments>
    </property>
    <property>
        <address>98320 County Rd 113</address>
        <price>155000</price>
        <comments>Small acreage outside of town</comments>
    </property>
</properties>

运行效果：

顺便附上GET和POST方法的相关代码：

var xmlHttp;

function createXMLHttpRequest() {

获取XMLHttpRequest代码……

}

function createQueryString() {

var firstName = document.getElementById("firstName").value;

var middleName = document.getElementById("middleName").value;

var birthday = document.getElementById("birthday").value;

var queryString = "firstName=" + firstName + "&middleName=" + middleName + "&birthday=" + birthday;

return queryString;

}

function doRequestUsingGET() {

createXMLHttpRequest();

var queryString = "data.txt?";

queryString = queryString + createQueryString()

+ "&timeStamp=" + new Date().getTime();

xmlHttp.onreadystatechange = handleStateChange;

xmlHttp.open("GET", queryString, true);

xmlHttp.send(null);

}

function doRequestUsingPOST() {

createXMLHttpRequest();

var url = "data.txt?timeStamp=" + new Date().getTime();

var queryString = createQueryString();

xmlHttp.open("POST", url, true);

xmlHttp.onreadystatechange = handleStateChange;

xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

/* 含义是表示客户端提交给服务器文本内容的编码方式是URL编码，即除了标准字符外，每字节以双字节16进制前加个“%”表示,
setRequestHeader方法只是XMLHTTP为添加或修改HTTP头提供的一个接口方法而已，至于里面的值则是HTTP协议的含义. */

xmlHttp.send(queryString);

}

function handleStateChange() {

if(xmlHttp.readyState == 4) {

if(xmlHttp.status == 200) {

parseResults();

}

function parseResults() {

var responseDiv = document.getElementById("serverResponse");

if(responseDiv.hasChildNodes()) {

responseDiv.removeChild(responseDiv.childNodes[0]);

}

var responseText = document.createTextNode(xmlHttp.responseText);

responseDiv.appendChild(responseText); }

post xml文件

function createXML() {

var xml = "<pets>";

var options = document.getElementById("petTypes").childNodes;

var option = null;

for(var i = 0; i < options.length; i++) {

option = options[i];

if(option.selected) {

xml = xml + "<type>" + option.value + "</type>";

}

xml = xml + "</pets>"; return xml;

}

function sendPetTypes() {

createXMLHttpRequest();

var xml = createXML();

var url = "data.txt?timeStamp=" + new Date().getTime();

xmlHttp.open("POST", url, true);

xmlHttp.onreadystatechange = handleStateChange;

xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

xmlHttp.send(xml);

}

</script>

发送json数据到后台：

function doJSON() {
    var car = getCarObject();
    //Use the JSON JavaScript library to stringify the Car object
    var carAsJSON = JSON.stringify(car);
    alert("Car object as JSON: " + carAsJSON);
    var url = "data.txt?timeStamp=" + new Date().getTime();
    createXMLHttpRequest();
    xmlHttp.open("POST", url, true);
    xmlHttp.onreadystatechange = handleStateChange;
    xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xmlHttp.send(carAsJSON);
}

function getCarObject() {

此处可以获取表单数据，代替下面的参数……

return new Car("Dodge", "Coronet R/T", 1968, "yellow");

}

function Car(make, model, year, color)

{ this.make = make; this.model = model; this.year = year; this.color = color; }