表单标签的使用

最新推荐文章于 2022-11-16 17:06:35 发布

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最新推荐文章于 2022-11-16 17:06:35 发布

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分类专栏： spring-mvc 文章标签： html 表单库 jsp

本文链接：https://blog.youkuaiyun.com/LuFei_java/article/details/75642655

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表单标签库

表单标签库中包含了可以用在jsp页面中渲染HTML元素的标签。为了使用这些标签，必须在jsp页面中的开头出声明taglib指令。

<%@ taglib prefix="form" uri="http://springframework.org/tags/form" %>

在表单标签库中的标签

标签	描述
form	渲染表单元素
input	渲染 `<input type="text"/>` 元素
password	渲染 `<input type="password"/>` 元素
hidden	渲染`<input ttpe="hidden"/>` 元素
textarea	渲染textarea元素
checkbox	渲染一个`<input type="checkbox"/>元素`
checkboxes	渲染多个`<input type="checkbox"/>`元素
radiobutton	渲染一个`<input type="redioButton"/>`元素
radiobuttons	渲染多个`<input type="redioButton"/>`元素
select	渲染一个选择元素
option	渲染一个可选元素
options	渲染一个可选元素列表
errors	在span元素中渲染字段错误

表单标签用于渲染HTML表单。表单标签必须利用渲染表单输入字段的其他任意标签。

<form:form commandName="book" action="book_save" method="post">
<!-- commandName属性或许是最重要的属性，因为它定义了模型（Model）属性的名称，其中包含了一个backing object,其属性将用于填充所生成的表单。如果该属性存在，则必须再返回包含该视图的请求处理方法中添加相应的模型属性 -->
</form:form>

表单标签的属性

属性	描述
acceptCharset	定义服务器接受的字符编码列表
commandName	暴露表单对象之模型属性的名称，默认为command
cssClass	定义要应用到被渲染form元素的CSS类
cssStyle	定义要应用到被渲染form元素的CSS样式
htmlEscape	接受true或者false，表示被渲染的值是否应该进行HTML转义
modeAttribute	暴露form backing object 的模型属性名称，默认为commend

展示代码部分

@RequestMapping(value="/页面路径")
public String inputBook(Model model){
    ...
    model.addAttribute("book", new Book());
    return "要跳转的页面";
}

在代码当中此处用book属性创建了一个Book对象，并添加到Model.如果没有Model属性，跳转的页面就会抛出异常，因为表单标签无法找到在其commandName属性中指定的dorm backing object.

input标签

input标签渲染<input type="text"/>元素。这个标签最重要的属性是path，它将这个输入字段绑定到form backing object的一个属性。例如，若随附<form/>标签的commandName属性值为book,并且input属性值为isbn，那么，input标签将被绑定到Book对象的isbn属性。

input标签的属性

属性	描述
cssClass	定义要应用到被渲染input元素的css类
cssStyle	定义要应用到被渲染input元素的css样式
cssErrorClass	定义要应用到被渲染input元素的css类，如果bound属性中包含错误，则覆盖cssClass属性值
htmlEscape	接受true或者false，表示十分应该对被渲染的值进行HTML转义
path	要绑定的属性路径

举个例子
<form:input id="isbn" path="isbn" cssErrorClass="errorBox"/>
他将会被渲染成下面的<input/>元素：
<input type="text" id="isbn" name="isbn"/>
cssErrorClass属性不起作用，除非isbn属性中输入验证错误，并且采用同一个表单重行显示用户输入，在这种情况下，input标签就会被渲染成下面这个input元素。
<input type="text" id="isbn" name="isbn" class="errorBox"/>
input标签也可以绑定到嵌套对象的属性。例如，下列的input标签绑定到form backing object的category属性的id属性。
<form:input path="categery.id"/>
剩下的标签就不一一介绍，如果读者感兴趣看文档会更详细。

一个小的例子

项目结构
domain里面的bean

package domain;

import java.io.Serializable;

public class Book implements Serializable{
    private static final long serialVersionUID = 7461688389112847430L;

    private long id;
    private String isbn;
    private String title;
    private Category category;
    private String author;
    public Book(){}//无参的构造方法
    //有参的构造方法
    public Book(long id, String isbn, String title, Category catgory, String author){
        this.id = id;
        this.isbn = isbn;
        this.title = title;
        this.category = catgory;
        this.author = author;
    }

    //get and set method
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getIsbn() {
        return isbn;
    }
    public void setIsbn(String isbn) {
        this.isbn = isbn;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public Category getCategory() {
        return category;
    }
    public void setCategory(Category category) {
        this.category = category;
    }
    public String getAuthor() {
        return author;
    }
    public void setAuthor(String author) {
        this.author = author;
    }   
}

package domain;

import java.io.Serializable;

public class Category implements Serializable{
    private static final long serialVersionUID = -6019865946011659102L;
    private int id;
    private String name;
    public Category(){}//无参
    //Constructor with arguments
    public Category(int id, String name) {
        this.id = id;
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    //get and set method

}

控制器的相关类

package controller;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import domain.Book;
import domain.Category;

import java.util.List;

import service.BookService;

@Controller
public class BookController {
    @Autowired
    private BookService bookService;

    private static final Log logger = LogFactory.getLog(BookController.class);

    @RequestMapping(value="/book_input")
    public String inputBook(Model model){
        List<Category> category = bookService.getAllcategories();
        model.addAttribute("book", new Book());
        model.addAttribute("category", category);
        return "BookAddForm";
    }

    @RequestMapping(value="/book_edit/{id}")
    public String editBook(Model model, @PathVariable long id){
        List<Category> category = bookService.getAllcategories();
        model.addAttribute("category", category);
        Book book = bookService.get(id);
        model.addAttribute("book", book);
        return "BookEditForm";
    }

    @RequestMapping(value="/book_save")
    public String saveBook(@ModelAttribute Book book){
        Category category = bookService.getCategory(book.getCategory().getId());
        book.setCategory(category);
        bookService.save(book);
        return "redirect:/book_list";
    }

    @RequestMapping(value="/book_update")
    public String updateBook(@ModelAttribute Book book){
        Category category = bookService.getCategory(book.getCategory().getId());
        book.setCategory(category);
        bookService.update(book);
        return "redirect:/book_list";
    }

    @RequestMapping(value="/book_list")
    public String listBooks(Model model){
        logger.info("book_list");
        List<Book> books = bookService.getAllBooks();
        model.addAttribute("books", books);
//      System.out.println("进入");
        return "BookList";
    }
}

实现的方法以及接口servlet

package service;

import java.util.List;

import domain.Book;
import domain.Category;

public interface BookService {
    List<Category> getAllcategories();
    Category getCategory(int id);
    List<Book> getAllBooks();
    Book save(Book book);
    Book update(Book book);
    Book get(long id);
    long getNextId();
}

package service;

import java.util.ArrayList;
import java.util.List;

import org.springframework.stereotype.Service;

import domain.Book;
import domain.Category;
@Service
public class BookServiceImpl implements BookService{
    /*
     * this implementation is not thread-safe
     */
    private List<Category> category;
    private List<Book> books;

    public BookServiceImpl() {
        category = new ArrayList<>();
        Category category1 = new Category(1, "Computing");
        Category category2 = new Category(2, "Travel");
        Category category3 = new Category(3, "Health");
        category.add(category1);
        category.add(category2);
        category.add(category3);

        books = new ArrayList<>();
        books.add(new Book(1L, "9780980839623", "servlet & jsp: a tutorial", category1, "Budi Kurniawan"));
        books.add(new Book(2L, "9780980839620", "c# A Beginner's Tutorial", category1, "Jayden Ky"));
    }

    @Override
    public List<Category> getAllcategories() {
        return category;
    }

    @Override
    public Category getCategory(int id) {
        for(Category category1 : category)
            if(id == category1.getId())
                return category1;
        return null;
    }

    @Override
    public List<Book> getAllBooks() {
        return books;
    }

    //执行添加操作
    @Override
    public Book save(Book book) {
        book.setId(getNextId());
        books.add(book);
        return book;
    }

    //执行更新操作
    @Override
    public Book update(Book book) {
        int bookCount = books.size();
        for(int i = 0; i < bookCount; i++){
            Book savedBook = books.get(i);
            if(savedBook.getId() == book.getId()){
                books.set(i, book);
                return book;
            }
        }
        return book;
    }

    //获取书籍的内容
    @Override
    public Book get(long id) {
        for(Book book : books){
            if(id == book.getId())
                return book;
        }
        return null;
    }

    @Override
    public long getNextId() {
        //needs to be locked
        long id = 0L;
        for(Book book : books){
            long bookId = book.getId();
            if(bookId > id)
                id = bookId;
        }
        return id + 1;
    }

}

jsp片段

<!--BookAddForm.jsp-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Add Book Form</title>
<style type="text.css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>
<!-- 添加书籍的信息 -->
<div id="global">
    <form:form commandName="book" action="book_save" method="post">
        <fieldset>
            <legend>Add a book</legend>
            <p>
                <label for="category">Category:</label>
                <form:select id="category" path="category.id" items="${category}"
                itemLabel="name" itemValue="id"/>
            </p>
            <p>
                <label for="title">Title:</label>
                <form:input id="title" path="title"/>
            </p>
            <p>
                <label for="author">Author:</label>
                <form:input path="author" id="author"/>
            </p>
            <p>
                <label for="isbn">ISBN:</label>
                <form:input path="isbn" id="isbn"/>
            </p>
            <p id="buttons">
                <input id="reset" type="reset" tabindex="4" value="reset"/>
                <input id="submit" type="submit" tabindex="5" value="Add Book"/>
            </p>
        </fieldset>
    </form:form>
</div>
</body>
</html>

<!-- BookEditForm.jsp -->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Edit Book Form</title>
<style type="text.css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>
<!-- 执行更新操作的页面 -->
<div id="global">
    <form:form commandName="book" action="book_update" method="post">
        <fieldset>
            <legend>Edit Book Form</legend>
            <form:hidden path="id"/>
            <p>
                <label for="category">Category:</label>
                <form:select id="category" path="category.id" items="${category}"
                itemLabel="name" itemValue="id"/>
            </p>
            <p>
                <label for="title">Title:</label>
                <form:input id="title" path="title"/>
            </p>
            <p>
                <label for="author">Author:</label>
                <form:input path="author" id="author"/>
            </p>
            <p>
                <label for="isbn">ISBN:</label>
                <form:input path="isbn" id="isbn"/>
            </p>
            <p id="buttons">
                <input id="reset" type="reset" tabindex="4" value="reset"/>
                <input id="submit" type="submit" tabindex="5" value="Update Book">
            </p>
        </fieldset>
    </form:form>
</div>
</body>
</html>

<!-- BookList.jsp -->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Book List</title>
<style type="text.css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>
<div id="global">
    <h1>Book List</h1>
    <a href="<c:url value="/book_input"/>">Add Book</a>
    <table>
        <tr>
            <th>Category</th>
            <th>Title</th>
            <th>ISBN</th>
            <th>Author</th>
            <th>&nbsp;</th>
        </tr>
        <c:forEach items="${books }" var="book">
            <tr>
                <td>${book.category.name}</td>
                <td>${book.title }</td>
                <td>${book.isbn }</td>
                <td>${book.author }</td>
                <td><a href="book_edit/${book.id}">Edit</a></td>
            </tr>
        </c:forEach>
    </table>
</div>
</body>
</html>

xml的基本配置

<!--web.xml-->
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <servlet>
        <servlet-name>spring</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/config/spring-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>spring</servlet-name>
        <!-- map all requests to the DispatcherServlet -->
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

<!-- spring-config.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd 
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        ">
        <context:component-scan base-package="controller"></context:component-scan>
        <context:component-scan base-package="service"></context:component-scan>
        <mvc:annotation-driven/>
        <mvc:resources mapping="/css/**" location="/css/"></mvc:resources>
        <mvc:resources location="/" mapping="/*.html"></mvc:resources>
        <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <property name="suffix" value=".jsp"></property>
        </bean>
</beans>