5.数据绑定和表单标签库

1.有了数据绑定，类型总是为了String的HTTP请求参数，可用于填充不同的类型的对象属性

2.表单标签库

为了使用这些标签，必须在jsp页面开头处声明这个taglib指令

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

form,input,password,hidden,textarea,checkbox,checkboxs,radiobutton,radiobuttons

select,option,options,errors渲染元素

表单标签

<form:form commandName="book" action="book_save" method="post">
</form>

commandName它定义了模型属性的名称，其属性用于填充所生成的表单

@RequestMapping("/book_input")
public String inputBook(Model model){

     model.addAttribute("book",new Book());       
}

如果没有Model属性，jsp会报错，无法找到commandName属性

input标签：

 1 <form:input id="isbn" path="isbn" cssErrorClass="errorBox">

 2 </form>


path:属性，它将这个输入的字段绑定到book的一个属性，绑定到book的isbn属性 5  

数据绑定范例：

1.Domain

package app05a.domain;

import java.io.Serializable;

public class Book implements Serializable {
    
    private static final long serialVersionUID = 1520961851058396786L;
    private long id;
    private String isbn;
    private String title;
    private Category category;
    private String author;
    
    public Book() {
    }
    
    public Book(long id, String isbn, String title, 
            Category category, String author) {
        this.id = id;
        this.isbn = isbn;
        this.title = title;
        this.category = category;
        this.author = author;
    }

    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 app05a.domain;

import java.io.Serializable;

public class Category implements Serializable {
    private static final long serialVersionUID = 5658716793957904104L;
    private int id;
    private String name;
    
    public Category() {
    }
    
    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;
    }
}

3.Controller

package app05a.controller;

import java.util.List;

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 app05a.domain.Book;
import app05a.domain.Category;
import app05a.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> categories = bookService.getAllCategories();
        model.addAttribute("categories", categories);
        model.addAttribute("book", new Book());
        return "BookAddForm";
    }

    @RequestMapping(value = "/book_edit/{id}")
    public String editBook(Model model, @PathVariable long id) {
        List<Category> categories = bookService.getAllCategories();
        model.addAttribute("categories", categories);
        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);
        return "BookList";
    }
}

4.Service

package app05a.service;

import java.util.List;

import app05a.domain.Book;
import app05a.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();

}

5.

package app05a.service;

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

import org.springframework.stereotype.Service;

import app05a.domain.Book;
import app05a.domain.Category;

@Service
public class BookServiceImpl implements BookService {
    
    /*
     * this implementation is not thread-safe
     */
    private List<Category> categories;
    private List<Book> books;
    
    public BookServiceImpl() {
        categories = new ArrayList<Category>();
        Category category1 = new Category(1, "Computing");
        Category category2 = new Category(2, "Travel");
        Category category3 = new Category(3, "Health");
        categories.add(category1);
        categories.add(category2);
        categories.add(category3);
        
        books = new ArrayList<Book>();
        books.add(new Book(1L, "9780980839623", 
                "Servlet & JSP: A Tutorial", 
                category1, "Budi Kurniawan"));
        books.add(new Book(2L, "9780980839630",
                "C#: A Beginner's Tutorial",
                category1, "Jayden Ky"));
    }

    @Override
    public List<Category> getAllCategories() {
        return categories;
    }
    
    @Override
    public Category getCategory(int id) {
        for (Category category : categories) {
            if (id == category.getId()) {
                return category;
            }
        }
        return null;
    }

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

    @Override
    public Book save(Book book) {
        book.setId(getNextId());
        books.add(book);
        return book;
    }

    @Override
    public Book get(long id) {
        for (Book book : books) {
            if (id == book.getId()) {
                return book;
            }
        }
        return null;
    }
    
    @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;
    }
    
    @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;
    }
}

5.配置文件

<?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="app05a.controller"/>
    <context:component-scan base-package="app05a.service"/>
     
    <mvc:annotation-driven/>
    <mvc:resources mapping="/css/**" location="/css/"/>
    <mvc:resources mapping="/*.html" location="/"/>
    
    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    
</beans>

6.视图

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML>
<html>
<head>
<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>

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML>
<html>
<head>
<title>Add Book Form</title>
<style type="text/css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>

<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="${categories}" 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 id="author" path="author"/>
        </p>
        <p>
            <label for="isbn">ISBN: </label>
            <form:input id="isbn" path="isbn"/>
        </p>
        
        <p id="buttons">
            <input id="reset" type="reset" tabindex="4">
            <input id="submit" type="submit" tabindex="5" 
                value="Add Book">
        </p>
    </fieldset>
</form:form>
</div>
</body>
</html>

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML>
<html>
<head>
<title>Edit Book Form</title>
<style type="text/css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>

<div id="global">
<form:form commandName="book" action="/book_update" method="post">
    <fieldset>
        <legend>Edit a book</legend>
        <form:hidden path="id"/>
        <p>
            <label for="category">Category: </label>
             <form:select id="category" path="category.id" items="${categories}"
                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 id="author" path="author"/>
        </p>
        <p>
            <label for="isbn">ISBN: </label>
            <form:input id="isbn" path="isbn"/>
        </p>
        
        <p id="buttons">
            <input id="reset" type="reset" tabindex="4">
            <input id="submit" type="submit" tabindex="5" 
                value="Update Book">
        </p>
    </fieldset>
</form:form>
</div>
</body>
</html>

7.测试应用

http://localhost:8080/app05a/book_list