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JSP learning 3

2022-04-23 16:06:00 【If you believe】

1、jsp action

<%@ page contentType="text/html; charset=UTF-8" pageEnconding="UTF-8" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
        <title></title>
    </head>
    <body>
        <%--
            jsp action ：
                 Format ：<jsp: denomination of dive   Property name = Property value   Property name = Property value ......></jsp: denomination of dive >
                1、forward action 
                 Example ： Current page 
                    <body>
                         handsome guy <br>
                        <jsp:forward page="/net.jsp"></jsp:forward>
                    </body>
                 stay net.jsp in 
                    <body>
                         beauty 
                    </body>
                 The result page only outputs beauty , Without outputting handsome men 

                2、include action 
                 Example ： Current page 
                    <body>
                         handsome guy <br>
                        <jsp:include page="/net.jsp"></jsp:include>
                        <%=a%>// Will report a mistake 
                    </body>
                 stay net.jsp in 
                    <body>
                         beauty <br>
                        <%
                        String a="11";
                        %>
                    </body>
                 The result page outputs handsome men and beautiful women , And no output a
        --%>

    </body>
    
</html>

2、EL expression （1）

<%@ page contentType="text/html; charset=UTF-8" pageEnconding="UTF-8" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
        <title></title>
    </head>
    <body>
       <%--
       EL expression ： Data can only be obtained from four domains , And cannot be assigned 
                 use ${
    } You can get the value , And show it 
                 Example 1：<body>
                        <%
                        String user="11";
                        %>
                        user=${
    user}
                     </body>
                      result ：user=     No, user Value 
                 Example 2：<body>
                        <%
                        String user="11";
                        request.setAttribute("user",user);
                        %>
                        user=${
    user}
                       </body>
                        result ：user=11
                 Example 3：<body>
                        <%
                            pageContext.setAttribute("add","11");
                            request.setAttribute("add","22");
                            session.setAttribute("add","33");
                            application.setAttribute("add","44"); 
                        %>
                        add=${
    add}
                        // The order of query is pageContext,request,session,application
                        // Display after query , Refreshing the page will query the next 
                       </body>
       --%>

    </body>
    
</html>

bean attribute
EL Of Bean attribute ： First step ： Create a class

      
                       package com;
                       public class Student{
    
                           private String name;
                           private int age;
                       
                       public Student(){
    
                           super();
                       }
                       public Student(){
    
                           super();
                           this.name=name;
                           this.age=age;
                       }
                       public void setName(String name){
    
                           this.name=name;
                       }
                       public String getName(){
    
                           return name;
                       }
                       public void setAge(int age){
    
                           this.age=age;
                       }
                       public int getAge(){
    
                           return age;
                       }
                       @Override
                       public String toString(){
    
                           return "Student[name="+name+",age="+age+"]";
                       } 
                       }

The second step , stay jsp Use in

<%@ page contentType="text/html; charset=UTF-8" pageEnconding="UTF-8" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
        <title></title>
    </head>
    <body>
 
                    <%
                    Student student=new Student(" Zhang San ",25);
                    pageContext.setAttribute("student",student);
                    %>
                    student=${
    student}<!-- Accept student All the values -->
                    name=${
    student.name}<!-- Accept student in name Value -->

    </body>
    
</html>

版权声明
本文为[If you believe]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/04/202204231404212069.html

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