准备我们心爱的IDEA写Jsp

JSP学习

一、准备我们心爱的IDEA

new一个项目：New Project --> Next -->Next -->Finsh

二、配置好服务器Tomcat-9.0.30

1.> 在WEB-INF下创建一个Lib包

将jsp-api.jar复制进去，并使其生效

未生效前：

生效过程：

2.> 用锤子配置汤姆猫TomCat

点击+ 号 选择本地的汤姆猫

在Deployment中的 + 号 选择Artifat

将多余的名称删去，为了方便找到

三、编写JSP文件

1.> 在web包下创建以.jsp为后缀名的文件

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

  
    
  
  
  $END$
  

2.>语法

JSP注释：为代码作注释以及将某段代码注释掉。

<%-- 该部分注释在网页中不会被显示--%>

<%-- 注释 --%> JSP注释，注释内容不会被发送至浏览器甚至不会被编译

脚本程序的语法格式：

<% 代码片段 %>

JSP表达式

<%= 表达式 %>

四、写个代码爽一下

运行–前提网址正确

1.>求字符串的长度

<%--
  Created by IntelliJ IDEA.
  User: 86156
  Date: 2023/9/4
  Time: 10:28
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    



<%--java代码在下面的标识里面写入<%%>中--%>
<%
    String str = "hello";
    out.println("字符串长度为：" + str.length() + "，字符串：" + str);

%>

运行结果：

网络：http://localhost:8080/FirstWeb2_war_exploded/strlen.jsp

2.>计算数组平均值

<%--
  Created by IntelliJ IDEA.
  User: 86156
  Date: 2023/9/18
  Time: 9:15
  To change this template use File | Settings | File Templates.
--%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>



    
    


<%
    int arraySize = 5;
    int[] numbers = new int[arraySize];

    numbers[0] = 10;
    numbers[1] = 20;
    numbers[2] = 30;
    numbers[3] = 40;
    numbers[4] = 50;

    int sum = 0;

    for (int i = 0; i < arraySize; i++) {
        sum += numbers[i];
    }

    double average = (double) sum / arraySize;
%>

平均值是：<%= average %>

http://localhost:8080/FirstWeb2_war_exploded/IntARRay.jsp

3.>九九乘法表

方式一：

<%--
  Created by IntelliJ IDEA.
  User: 86156
  Date: 2023/9/11
  Time: 11:16
  To change this template use File | Settings | File Templates.
--%>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>



    



        <% for (int i = 1; i <= 9; i++) { %>
        
        <% } %>
    
    <% for (int i = 1; i <= 9; i++) { %>
    
        <% for (int j = 1; j <= 9; j++) { %>
        <% int result = i * j; %>
        
        <% } %>
    
    <% } %>

    

        
<%= i %>

        
<%= i %>
"><%= i %> * <%= j %> = <%= result %>

http://localhost:8080/FirstWeb2_war_exploded/multitable1.jsp

方式二：

<%--
  Created by IntelliJ IDEA.
  User: 86156
  Date: 2023/9/11
  Time: 10:55
  To change this template use File | Settings | File Templates.
--%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>



    



        <% for (int i = 1; i <= 9; i++) { %>
        
        <% } %>
    
    <% for (int i = 1; i <= 9; i++) { %>
    
        <% for (int j = 1; j <= 9; j++) { %>
        <% int result = i * j; %>
        <% if (j >= i) { %>
        
        <% } else { %>
        
        <% } %>
        <% } %>
    
    <% } %>

    

        
<%= i %>

        
<%= i %>
"><%= i %> * <%= j %> = <%= result %>

http://localhost:8080/FirstWeb2_war_exploded/multitalbe2.jsp

4.>获取圆的面积：

STEP1：编写一个圆的类

在src下，new一个包，包下new一个class文件为circle

如图：

写好私有域的r，利用ptg快速生成JavaBean (ptg可以在插件中下载）

package cn.heima.circle2;

public class Circle {
    private  double r;

    public Circle() {
    }

    public Circle(double r) {
        this.r = r;
    }

    /**
     * 获取
     * @return r
     */
    public double getR() {
        return r;
    }

    /**
     * 设置
     * @param r
     */
    public void setR(double r) {
        this.r = r;
    }

    public String toString() {
        return "Circle{r = " + r + "}";
    }
    public  double getAreacIR(){
        return  Math.PI*this.r*this.r;
    }
}

STEP2：在JSP文件下导入Circle文件：

导入方法

<%@ page import="cn.heima.circle2.Circle" %>

<%--
  Created by IntelliJ IDEA.
  User: 86156
  Date: 2023/9/11
  Time: 11:27
  To change this template use File | Settings | File Templates.
--%>
<%--
  Created by IntelliJ IDEA.
  User: 86156
  Date: 2023/9/11
  Time: 11:27
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="cn.heima.circle2.Circle" %>


    


<%
    Circle c = new Circle(1.0);
    out.print(c.getAreacIR());
%>

结果