JSTL tag error: & lt; c: forEach var = & quot; book & quot; items = & quot ;$ {requestScope. books} & quot; varStatus = & quot; status & quot; & gt;, jstlvarstatus

Error in JSTL label: <c: forEach var = "book" items = "$ {requestScope. books}" varStatus = "status">, jstlvarstatus

An error occurred while running the JSTL label code in the book today. The following is a summary:

Question 1.The JSP specification requires that an attribute name is preceded by whitespace 

Solution: <c: forEach var = "book" items = "$ {requestScope. books}" varStatus = "status"> Error

Changed to: <c: forEach var = "book" items = "$ {requestScope. books}" varStatus = "status">

Cause: Add a space before varStatus = "status"

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Problem 2. Property 'isbn 'not found on type java. lang. String

Solution: <c: forEach var = "book" items = "$ {requestScope. books}" varStatus = "status"> Error

Changed to: <c: forEach var = "book" items = "$ {requestScope. books}" varStatus = "status">

Cause: Remove spaces before $ {requestScope. books}

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Problem 3: The program is running and jsp is accessible, but the EL expression cannot read the desired information.

Solution: The servlet <url-pattern> information is not added to the. xml configuration file,You cannot call servlet to send objects to jsp.

Add the following content to the. xml file:

<servlet>   <servlet-name>BooksServlet</servlet-name>   <servlet-class>com.controller.BooksServlet</servlet-class></servlet><servlet-mapping>   <servlet-name>BooksServlet</servlet-name>   <url-pattern>/BooksServlet</url-pattern></servlet-mapping>

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Jstl label exercise code:

1. BooksServlet. java

1 package com. controller; 2 import java. io. IOException; 3 import javax. servlet. requestDispatcher; 4 import javax. servlet. servletException; 5 import javax. servlet. annotation. webServlet; 6 import javax. servlet. http. httpServlet; 7 import javax. servlet. http. httpServletRequest; 8 import javax. servlet. http. httpServletResponse; 9 import java. util. list; 10 import java. util. arrayList; 11 import com. model. book; 12 // @ WebServlet ("/BooksServlet") 13 public class BooksServlet extends HttpServlet {14 @ Override15 public void doGet (HttpServletRequest request, HttpServletResponse response) 16 throws ServletException, IOException {17 List <Book> books = new ArrayList <Book> (); 18 Book book1 = new Book ("978-7-302-23059-5 ", "Java programming language", 45.00); 19 Book book2 = new Book ("978-7-302-21540-0", "Java Web Programming Technology", 39.00 ); 20 Book book3 = new Book ("978-7-302-24130-0", "C # entry classic", 99.80); 21 books. add (book1); 22 books. add (book2); 23 books. add (book3); 24 request. setAttribute ("books", books); 25 RequestDispatcher rd = request. getRequestDispatcher ("/books. jsp "); 26 rd. forward (request, response); 27} 28}

2. Book. java (javaBean class)

 1 package com.model; 2  3 public class Book { 4    private String isbn; 5    private String title; 6    private double price; 7    public Book(String isbn, String title, double price) { 8     super(); 9     this.isbn = isbn;10     this.title = title;11     this.price = price;12     }13     public String getIsbn() {14         return isbn;15     }16     public void setIsbn(String isbn) {17         this.isbn = isbn;18     }19     public String getTitle() {20         return title;21     }22     public void setTitle(String title) {23         this.title = title;24     }25     public double getPrice() {26         return price;27     }28     public void setPrice(double price) {29         this.price = price;30     }31         32    33 }

3. books. jsp

 1 package com.model; 2  3 public class Book { 4    private String isbn; 5    private String title; 6    private double price; 7    public Book(String isbn, String title, double price) { 8     super(); 9     this.isbn = isbn;10     this.title = title;11     this.price = price;12     }13     public String getIsbn() {14         return isbn;15     }16     public void setIsbn(String isbn) {17         this.isbn = isbn;18     }19     public String getTitle() {20         return title;21     }22     public void setTitle(String title) {23         this.title = title;24     }25     public double getPrice() {26         return price;27     }28     public void setPrice(double price) {29         this.price = price;30     }31         32    33 }

4. configuration file. xm

 1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> 3   <display-name>Ex_JSTL_tag</display-name> 4   <servlet> 5     <servlet-name>BooksServlet</servlet-name> 6     <servlet-class>com.controller.BooksServlet</servlet-class> 7   </servlet> 8   <servlet-mapping> 9     <servlet-name>BooksServlet</servlet-name>10     <url-pattern>/BooksServlet</url-pattern>11   </servlet-mapping>12   <welcome-file-list>13     <welcome-file>index.html</welcome-file>14     <welcome-file>index.htm</welcome-file>15     <welcome-file>books.jsp</welcome-file>16     <welcome-file>default.htm</welcome-file>17     <welcome-file>default.jsp</welcome-file>18   </welcome-file-list>19 </web-app>

5. Add http: // localhost/Ex_JSTL_tag/during running/BooksServlet

Only when/BooksServlet is added to the url can the servlet be called.

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