面试题及相关参考答案

原创

byte01 2022-11-28 15:16:00 ©著作权

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1、页面关闭之前执行js.(使用了js的onunload事件)

demo1:   
 　<html xmlns="http://www.w3.org/1999/xhtml">
　　　<head>
　　　<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
　　　<title>onunload测试</title>
　　　<script>
　　　function checkLeave(){
     　　　　alert("欢迎下次再来！");
在这里可以写你要执行的那个函数
　　　}
　　　</script>
　　　</head>
　　　<body onunload="checkLeave()">
　　　</body>
　　　</html>

demo2:

判断是刷新还是离开:
<HTML> 
<HEAD> 
<TITLE>判断是刷新还是关闭</TITLE> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"> 
<META NAME="Author" CONTENT="onunload"> 
<META NAME="Description" CONTENT="test js onunload event"> 
</HEAD> 
<script> 
function CloseOpen() { 
 if(event.clientX<=0 && event.clientY<0) { 
  alert("关闭"); 
 } 
 else 
 { 
  alert("刷新或离开"); 
 } 
} 
</script> 
<body onunload="CloseOpen()"> 
</BODY> 
</HTML>

2、当jsp页面完全加载完成后执行一个js函数（使用onload事件，js里有多种写法，了解一下）

方法1.如下程序，当页面完全加载后执行openTheIndexPage()方法

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>Telecommunications Data Collection System</title>
<script type="text/javascript" src="<%=contextPath%>/js/baseframe.js"></script>
<script type="text/javascript" src="<%=contextPath%>/js/cookies.js"></script>
<script type="text/javascript" src="<%=contextPath%>/js/tag/tag.js"></script>
<script language="javascript" for="window" event="onload"> 
    function openTheIndexPage() {     
        openMyURIWithCid(true, 'root', 'IDX', "iframe/dispatch.jsp?url=tdc/zhk/impctrlobjinf/index/index.jsp", '首页',
                'top.tagmenu', 'top.maintop', true,
                'system/accessPaths.do?currentModuleCode=IDX',
                'mainmenu', true);
    };
    if(document.readyState=="complete"){
        openTheIndexPage();
    } 
</script>
</head> 
<body> 
</body>    
</html>

方法2：可以是以下几种，但是效果不如方法1.

<body onload="function name()"> </body > 
<script>window.onload=function name </script> 
<script language="javascript" for="window" event="onload">function name(); </script>

方法3：<body onload="xxx()"> </body> xxx()为你要执行的函数

.csharpcode, .csharpcode pre { font-size: small; color: rgba(0, 0, 0, 1); font-family: consolas, "Courier New", courier, monospace; background-color: rgba(255, 255, 255, 1) }
.csharpcode pre { margin: 0 }
.csharpcode .rem { color: rgba(0, 128, 0, 1) }
.csharpcode .kwrd { color: rgba(0, 0, 255, 1) }
.csharpcode .str { color: rgba(0, 96, 128, 1) }
.csharpcode .op { color: rgba(0, 0, 192, 1) }
.csharpcode .preproc { color: rgba(204, 102, 51, 1) }
.csharpcode .asp { background-color: rgba(255, 255, 0, 1) }
.csharpcode .html { color: rgba(128, 0, 0, 1) }
.csharpcode .attr { color: rgba(255, 0, 0, 1) }
.csharpcode .alt { background-color: rgba(244, 244, 244, 1); width: 100%; margin: 0 }
.csharpcode .lnum { color: rgba(96, 96, 96, 1) }补充：

<script language= "javascript " for= "window " event= "onload " /> 的问题解读
EVENT   event   设置或获取脚本编写用于的事件
FOR   htmlFor   设置或获取绑定到事件脚本的对象。

<script   language= "javascript "   for= "window "   event= "onload ">

.csharpcode, .csharpcode pre { font-size: small; color: rgba(0, 0, 0, 1); font-family: consolas, "Courier New", courier, monospace; background-color: rgba(255, 255, 255, 1) }
.csharpcode pre { margin: 0 }
.csharpcode .rem { color: rgba(0, 128, 0, 1) }
.csharpcode .kwrd { color: rgba(0, 0, 255, 1) }
.csharpcode .str { color: rgba(0, 96, 128, 1) }
.csharpcode .op { color: rgba(0, 0, 192, 1) }
.csharpcode .preproc { color: rgba(204, 102, 51, 1) }
.csharpcode .asp { background-color: rgba(255, 255, 0, 1) }
.csharpcode .html { color: rgba(128, 0, 0, 1) }
.csharpcode .attr { color: rgba(255, 0, 0, 1) }
.csharpcode .alt { background-color: rgba(244, 244, 244, 1); width: 100%; margin: 0 }
.csharpcode .lnum { color: rgba(96, 96, 96, 1) }相当于

<script   language= "javascript "> 
//   绑定 
 window.attachEvent( "onload ",function()   { 
 }) 
</script>

3、js更改class

html:

<div id="a" class="dbl"> a content </div>
<div id="b" class="dno"> b content </div>
<div id="c" class="">c content</div?

css:
<style type="text/css">
.dbl{display:block;}
.dno{display:none;}
</style>

js:

<script language="javascript">
document.getElementById("a").onmouseover = function(){
   document.getElementById("a").className = "dno";
   document.getElementById("b").className = "dbl";
}
document.getElementById("b").onmouseout = function(){
   document.getElementById("a").className = "dbl";
   document.getElementById("b").className = "dno";
}

</script>

注意：js要放在最后面，css，html的位置随便

补充:

function change(obj,cal){

     var ok;
     if(document.all)
        { ok=obj.getAttribute("className")';
        }//for IE
        else
        {   ok=obj.getAttribute("class"); 
        }//for FF
     obj.className=ok;

  }

更改其它属性：.csharpcode, .csharpcode pre { font-size: small; color: rgba(0, 0, 0, 1); font-family: consolas, "Courier New", courier, monospace; background-color: rgba(255, 255, 255, 1) }
.csharpcode pre { margin: 0 }
.csharpcode .rem { color: rgba(0, 128, 0, 1) }
.csharpcode .kwrd { color: rgba(0, 0, 255, 1) }
.csharpcode .str { color: rgba(0, 96, 128, 1) }
.csharpcode .op { color: rgba(0, 0, 192, 1) }
.csharpcode .preproc { color: rgba(204, 102, 51, 1) }
.csharpcode .asp { background-color: rgba(255, 255, 0, 1) }
.csharpcode .html { color: rgba(128, 0, 0, 1) }
.csharpcode .attr { color: rgba(255, 0, 0, 1) }
.csharpcode .alt { background-color: rgba(244, 244, 244, 1); width: 100%; margin: 0 }
.csharpcode .lnum { color: rgba(96, 96, 96, 1) }

<div>
<a href="javascript:changeBody(1)">模块A</a> 
<a href="javascript:changeBody(2)">模块B</a> 
<a href="javascript:changeBody(3)">模块C</a> 
</div> 

<div style="display: none" id="iDBody1"></div> 
<div style="display: none" id="iDBody2"></div> 
<div style="display: none" id="iDBody3"></div>.csharpcode, .csharpcode pre { font-size: small; color: rgba(0, 0, 0, 1); font-family: consolas, "Courier New", courier, monospace; background-color: rgba(255, 255, 255, 1) }
.csharpcode pre { margin: 0 }
.csharpcode .rem { color: rgba(0, 128, 0, 1) }
.csharpcode .kwrd { color: rgba(0, 0, 255, 1) }
.csharpcode .str { color: rgba(0, 96, 128, 1) }
.csharpcode .op { color: rgba(0, 0, 192, 1) }
.csharpcode .preproc { color: rgba(204, 102, 51, 1) }
.csharpcode .asp { background-color: rgba(255, 255, 0, 1) }
.csharpcode .html { color: rgba(128, 0, 0, 1) }
.csharpcode .attr { color: rgba(255, 0, 0, 1) }
.csharpcode .alt { background-color: rgba(244, 244, 244, 1); width: 100%; margin: 0 }
.csharpcode .lnum { color: rgba(96, 96, 96, 1) }

function changeBody(index){
  switch(index){
    case 1:{
      document.getElementById('iDBody1').style.display = "";
      document.getElementById('iDBody2').style.display = "none";
      document.getElementById('iDBody3').style.display = "none";
    } break;
    case 2:{
      document.getElementById('iDBody1').style.display = "none";
      document.getElementById('iDBody2').style.display = "";
      document.getElementById('iDBody3').style.display = "none";
    } break;
    case 3:{
      document.getElementById('iDBody1').style.display = "none";
      document.getElementById('iDBody2').style.display = "none";
      document.getElementById('iDBody3').style.display = "";
    } break;
  }
}.csharpcode, .csharpcode pre { font-size: small; color: rgba(0, 0, 0, 1); font-family: consolas, "Courier New", courier, monospace; background-color: rgba(255, 255, 255, 1) }
.csharpcode pre { margin: 0 }
.csharpcode .rem { color: rgba(0, 128, 0, 1) }
.csharpcode .kwrd { color: rgba(0, 0, 255, 1) }
.csharpcode .str { color: rgba(0, 96, 128, 1) }
.csharpcode .op { color: rgba(0, 0, 192, 1) }
.csharpcode .preproc { color: rgba(204, 102, 51, 1) }
.csharpcode .asp { background-color: rgba(255, 255, 0, 1) }
.csharpcode .html { color: rgba(128, 0, 0, 1) }
.csharpcode .attr { color: rgba(255, 0, 0, 1) }
.csharpcode .alt { background-color: rgba(244, 244, 244, 1); width: 100%; margin: 0 }
.csharpcode .lnum { color: rgba(96, 96, 96, 1) }

参考资料：

5、更改tomcat接收请求的线程数


更改CATALINA_HOME(tomcat安装目录)/conf/server.xml文件中的以下节点中的maxThreads属性的值即可

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"
               maxThreads="800" acceptCount="1000"/>.csharpcode, .csharpcode pre { font-size: small; color: rgba(0, 0, 0, 1); font-family: consolas, "Courier New", courier, monospace; background-color: rgba(255, 255, 255, 1) }
.csharpcode pre { margin: 0 }
.csharpcode .rem { color: rgba(0, 128, 0, 1) }
.csharpcode .kwrd { color: rgba(0, 0, 255, 1) }
.csharpcode .str { color: rgba(0, 96, 128, 1) }
.csharpcode .op { color: rgba(0, 0, 192, 1) }
.csharpcode .preproc { color: rgba(204, 102, 51, 1) }
.csharpcode .asp { background-color: rgba(255, 255, 0, 1) }
.csharpcode .html { color: rgba(128, 0, 0, 1) }
.csharpcode .attr { color: rgba(255, 0, 0, 1) }
.csharpcode .alt { background-color: rgba(244, 244, 244, 1); width: 100%; margin: 0 }
.csharpcode .lnum { color: rgba(96, 96, 96, 1) }

相关信息:
tomcat6.x中Servlet容器的结构:
Server(容器)下有一个或多个Service,Service下有一个或多个Connector、一个engine，一个engine可以有多个host(虚拟主机，可以配域名和别名,可以决定是否识别新添加的web项目)，一个host中可以包括多个Context（web应用程序）

maxThreads：tomcat起动的最大线程数，即同时处理的任务个数，默认值为200
acceptCount：当tomcat起动的线程数达到最大时，接受排队的请求个数，默认值为100

这两个值如何起作用，请看下面三种情况
情况1：接受一个请求，此时tomcat起动的线程数没有到达maxThreads，tomcat会起动一个线程来处理此请求。
情况2：接受一个请求，此时tomcat起动的线程数已经到达maxThreads，tomcat会把此请求放入等待队列，等待空闲线程。
情况3：接受一个请求，此时tomcat起动的线程数已经到达maxThreads，等待队列中的请求个数也达到了acceptCount，此时tomcat会直接拒绝此次请求，返回connection refused

6、java和c#将String逐字母输出示例：
java:

public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str="Chinese123";
        for (int i = 0; i < str.length(); i++) {
            System.out.println(str.charAt(i));
        }
        
        char[] charArray=str.toCharArray();
        for (int i = 0; i < charArray.length; i++) {
            System.out.println(charArray[i]);
        }
    }

c#:

static void Main(string[] args)
        {
            String str = "Chinese123";
            for (int i = 0; i < str.Length; i++)
            {
                Console.WriteLine(str[i]);
            }
            Console.ReadKey();
        }

7、