Jsp在web开发中常用到的技术(一)
JSP学习总结
文章目录
- JSP学习总结
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- @[TOC](文章目录)
- 一、JSP快速入门
- 二、JSP原理
- 三、JSP脚本
- 四、EL表达式
- 五、JSTL
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- 标签
- 标签
- @[TOC](文章目录)
- 标签
- 标签
一、JSP快速入门
jsp坐标：
<dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>2.2</version> <scope>provided</scope> </dependency>案例：
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body><h1>Hello JSP</h1><% System.out.println("Hello JSP");%></body></html>运行结果：
二、JSP原理
三、JSP脚本
案例：
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title> <%! //定义两个变量 int a=1; int b=3; %> <%! //定义一个test方法 public String test(){ //定义一个变量str String str="小飞侠"; return str; } %></head><body><% //输出两个变量的和 System.out.println(a+b); //控制台输出4%><br><% //调用test方法，输出返回值 System.out.println(test()); //控制台输出小飞侠%><br><%=a+b %><br><%=test()%></body></html>运行结果：
四、EL表达式
案例：
package com.study.pojo;public class Student { private String id; //学号 private String name; //姓名 private String gender; //性别 private int age; //年龄 public Student() { } public Student(String id, String name, String gender, int age) { this.id = id; this.name = name; this.gender = gender; this.age = age; } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Student{" + "id='" + id + '\'' + ", name='" + name + '\'' + ", gender='" + gender + '\'' + ", age=" + age + '}'; }}package com.study.Servlet;import com.study.pojo.Student;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.ArrayList;import java.util.List;@WebServlet("/el")public class ElTestServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //准备数据 List<Student> stus=new ArrayList<>(); stus.add(new Student("001","小马哥","男",23)); stus.add(new Student("002","小飞侠","男",24)); stus.add(new Student("003","马奎斯","男",25)); //保存到request域中 req.setAttribute("students",stus); //req.setAttribute("status",1); req.getRequestDispatcher("/ElTest.jsp").forward(req,resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); }}<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@page isELIgnored="false" %><html><head> <title>Title</title></head><body>${students}</body></html>注意：如果输出页面是${students}，原因是缺少了一个能让页面识别el表达式的页头语句，在jsp页面头加:即可。
运行结果：
五、JSTL
标签
坐标：
<dependency> <groupId>jstl</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>taglibs</groupId> <artifactId>standard</artifactId> <version>1.1.2</version> </dependency>Jstl标签库：
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>案例：
package com.study.Servlet;import com.study.pojo.Student;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.ArrayList;import java.util.List;@WebServlet("/el")public class ElTestServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //准备数据 List<Student> stus=new ArrayList<>(); stus.add(new Student("001","小马哥","男",23)); stus.add(new Student("002","小飞侠","男",24)); stus.add(new Student("003","马奎斯","男",25)); //保存到request域中 req.setAttribute("students",stus); req.setAttribute("status",1); //转发到Jstl-if.jsp页面中 req.getRequestDispatcher("/Jstl-if.jsp").forward(req,resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); }}<%-- Created by IntelliJ IDEA. User: 86166 Date: 2022/6/14 Time: 11:27 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><%@page isELIgnored="false" %><html><head> <title>Title</title></head><body><c:if test="${status==1}"> <h1>访问成功！</h1></c:if></body></html>运行结果：
标签
items：遍历的容器
var:遍历产生的临时变量
varStatus:遍历状态对象
案例：
package com.study.Servlet;import com.study.pojo.Student;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.ArrayList;import java.util.List;@WebServlet("/el")public class ElTestServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //准备数据 List<Student> stus=new ArrayList<>(); stus.add(new Student("001","小马哥","男",23)); stus.add(new Student("002","小飞侠","男",24)); stus.add(new Student("003","马奎斯","男",25)); //保存到request域中 req.setAttribute("students",stus); //转发到forEach.jsp页面中 req.getRequestDispatcher("/forEach.jsp").forward(req,resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); }}<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><%@page isELIgnored="false" %><html><head> <title>Title</title></head><body><table border="1" bgcolor="#00ced1"> <tr> <td>学号</td> <td>姓名</td> <td>性别</td> <td>年龄</td> </tr> <c:forEach items="${students}" var="stu" varStatus="stuID"> <tr> <td>${stu.id}</td> <%--<td>${stuID.index}</td> //学号就变成了0,1,2--%> <td>${stu.name}</td> <td>${stu.gender}</td> <td>${stu.age}</td> </tr> </c:forEach></table></body></html>运行结果：
