Day68 JavaScript、Json
<head> <title>ECMAScript和页面结合之内部结合</title> <%--js脚本内部结合--%> <script> //打印语句 console.log("js脚本") </script> </head> <body> hello javascript </body>
- 外部结合
<head> <title>ECMAScript和页面结合之外部结合</title> <script src="${pageContext.request.contextPath}/myjs.js"></script> </head> <body> </body>
var num = 1; console.log(typeof(num));//number var str = "abc"; console.log(typeof(str));//string var flag = true; console.log(typeof(flag));//boolean var obj = null; console.log(typeof(obj));//Object var num1 ; console.log(typeof(num1));//undefined var num2 = NaN; console.log(typeof num2);//number
- 流程控制语句:switch
switch (true) { case true: console.log(true) break; case false: console.log(true) break; } for (var i = 0; i < 10; i++) { console.log(i) }
//parseInt var num1 = 1; var num2 = "1"; console.log(num1 + parseInt(num2)); console.log("--------------------") //isNaN:判断一个变量是否是NaN var num3 = NaN; console.log(num3 == NaN);//false console.log(num3 === NaN);//false console.log(isNaN(num3));//true console.log("--------------------") //eval:计算json字符串,返回js对象 var jsonStr = '{"username":"root","password":"root"}'; //不能通过上述的json字符串直接调用username属性和password属性,需要将json字符串转换成js对像
var jsObject = eval("("+jsonStr+")");
console.log(jsObject.username + " , " + jsObject.password)
public class Province { private Integer pId; private String pName; public Province() { } public Province(Integer pId, String pName) { this.pId = pId; this.pName = pName; } public Integer getpId() { return pId; } public void setpId(Integer pId) { this.pId = pId; } public String getpName() { return pName; } public void setpName(String pName) { this.pName = pName; } @Override public String toString() { return "Province{" + "pId=" + pId + ", pName='" + pName + '\'' + '}'; } }
- Demo.java
Province p1 = new Province(1,"卡布奇诺"); Province p2 = new Province(2,"拿铁"); //p1 -> json字符串 String jsonStr1 = "{'pId':1,'pName':'卡布奇诺'}"; String jsonStr2 = "{'pId':2,'pName':'拿铁'}";//单列集合 //Province List<Province> provinceList = new ArrayList<>(); provinceList.add(p1); provinceList.add(p2); // provinceList -> json字符串 String jsonStr3 = "[{'pId':1,'pName':'卡布奇诺'},{'pId':2,'pName':'拿铁'}]"; //双列集合 //entry : 键值对对象 Map<String,Province> map = new HashMap<>(); map.put("p1",p1); map.put("p2",p2); //map -> json字符串 String jsonStr4 = "[{'p1':{'pId':1,'pName':'卡布奇诺'}},{'p2':{'pId':2,'pName':'拿铁'}}]";