json的方法

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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'list.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

<script type="text/javascript">
/*
封装的发送ajax的函数
*url 发送请求的地址
*方法类型 get或者post
*参数通过键=值&键=值方式
*回调函数当结果返回后自动调用的函数第一个参数就是返回的结果
function（responseText）{
具体的逻辑（页面渲染）
}
*/
function sendAjax(url,methodType,param,retnFunction){
//无刷新调用 http://localhost:8080/s/queryFood 获取到数据数据通过dom方式添加到 table中
//ajax(异步的ajax)+json
var xmlhttp=null;
//兼容所有的瀏覽器創建這個對象 XHR對象
if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp = new XMLHttpRequest();
} else {// code for IE6, IE5
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
//回調函數當請求發送后收到結果自動調用該方法
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
retnFunction(xmlhttp.responseText)
}
}
if(methodType=="get" || methodType=="GET" ){
xmlhttp.open("GET", url+"?"+param, true);
xmlhttp.send();
}else{
xmlhttp.open("POST", url, true);
xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded;charset=UTF-8");
xmlhttp.send(param);
}
}
/*
使用ajax
尽量使用 true 异步模式（防假死）
尽量将获取数据之后的逻辑处理（页面渲染）放在回调函数中
*/

function query() {
var foodname=document.getElementsByName("foodName")[0].value;
sendAjax("${pageContext.request.contextPath}/queryFoodList","GET","foodname="+foodname,function(responseText){
//返回的是字符串的json
var resutlJson = responseText;
//轉換為js對象
var resultObj=JSON.parse(resutlJson);
//获取表格对象
var table=document.getElementById("myTable");
//将所有名字为 dataTr的tr全部删除 [a,b,c]
var allDataTr=document.getElementsByName("dataTr");
var length=allDataTr.length;
for(var i=0;i<length;i++){
table.removeChild(allDataTr[0]);
}

//根据json的行数追加多个tr
for(var i=0;i<resultObj.length;i++){
var obj=resultObj[i];
var td=document.createElement("td");
td.innerText=obj.foodname;
var td1=document.createElement("td");
td1.innerText=obj.price;

var td2=document.createElement("td");
//删除按钮
var ib=document.createElement("button");
ib.innerText="X";
var ib1=document.createElement("button");
ib1.innerText="U";
td2.appendChild(ib);
td2.appendChild(ib1);
var tr=document.createElement("tr");
//将当前行的json对象绑定到当前按钮上
ib.foodObj=obj;
//将当前行的tr绑定到当前按钮上
ib.myLineTr=tr;
//删除按钮时间
ib.addEventListener("click",function(){
//获取当前按钮
var eventSrc=event.srcElement;
//删除当前行 + 发送ajax请求到后台删除数据库
table.removeChild(eventSrc.myLineTr);
sendAjax("${pageContext.request.contextPath}/food/"+ib.foodObj.foodid,"POST","_method=delete",function(responseText){
if(responseText==1)
alert("删除成功");
else{
alert("删除失败");
}
});

});
ib1.foodObj=obj;
ib1.addEventListener("click",function(){
var eventSrc=event.srcElement;
document.getElementById('updateDiv').style.display='block';
document.getElementsByName("umyFoodName")[0].value=eventSrc.foodObj.foodname;
document.getElementsByName("umyFoodPrice")[0].value=eventSrc.foodObj.price;
document.getElementsByName("umyFoodId")[0].value=eventSrc.foodObj.foodid;

})

tr.setAttribute("name","dataTr");
tr.appendChild(td);
tr.appendChild(td1);
tr.appendChild(td2);
table.appendChild(tr);
}

})

}
/**
新增的方法
**/
function saveFood(){
var myFoodName=document.getElementsByName("myFoodName")[0].value;
var myFoodPrice=document.getElementsByName("myFoodPrice")[0].value;
sendAjax("${pageContext.request.contextPath}/food","POST","foodName="+myFoodName+"&price="+myFoodPrice,function(responseText){
if(responseText==1){
document.getElementById('addDiv').style.display='none';
query();
alert("新增成功");

}else{
alert("新增失败");
}
});

}

/**
修改的方法
**/
function updateFood(){
var myFoodName=document.getElementsByName("umyFoodName")[0].value;
var myFoodPrice=document.getElementsByName("umyFoodPrice")[0].value;
var myFoodId=document.getElementsByName("umyFoodId")[0].value;
sendAjax("${pageContext.request.contextPath}/food/"+myFoodId,"POST","_method=put&foodName="+myFoodName+"&price="+myFoodPrice,function(responseText){
if(responseText==1){
document.getElementById('updateDiv').style.display='none';
query();
alert("修改成功");

}else{
alert("修改失败");
}
});

}

</script>
</head>

<body>
<input type='text' name="foodName" />
<input type='button' value="查询" onclick="query()"><input type='button' value="新增" onclick="document.getElementById('addDiv').style.display='block';">
<table id="myTable">
<tr><th>菜品名</th><th>菜品价格</th><th>操作</th></tr>
</table>
</body>

<div id="addDiv" style="display:none;position: absolute;left:40%;top:40%;z-index: 100;border:1px solid black; width:250px;height:100px ">

菜品名：<input type="text" name="myFoodName"><br/>
价   格：<input type="text" name="myFoodPrice"><br/>
<input type="button" value="保存" onclick="saveFood()">   <input type="button" value="关闭" onclick="document.getElementById('addDiv').style.display='none';" ><br/>
</div>

<div id="updateDiv" style="display:none;position: absolute;left:40%;top:40%;z-index: 100;border:1px solid black; width:250px;height:100px ">
<input type="hidden" name="umyFoodId" >
菜品名：<input type="text" name="umyFoodName"><br/>
价   格：<input type="text" name="umyFoodPrice"><br/>
<input type="button" value="修改" onclick="updateFood()">   <input type="button" value="关闭" onclick="document.getElementById('updateDiv').style.display='none';" ><br/>
</div>

</html>

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