本次学习中学到基于注解的控制器和数据绑定和表单标签。在前面的程序中控制器都是继承Controller接口，现在要用有注解的控制器。
使用注解控制器的优点：
实现controller接口的控制器只能处理一个动作，不过注解的控制器类可以处理多个动作，从而减少应用程序中类的数量。
基于注解的控制器的请求映射不需要存储在配置文件中。本次学习中学到的注解类型
@Controller：用于指示Spring类的实例是一个控制器。@Controller public class ProductController{}
spring使用扫描机制来找到应用程序中所有就注解的控制器类。 需要在Spring MVC配置文件中声明SpringContext和元素。
<beans
...
xmlns:context="http://www.springframework.org/schema/context"
...
>
<context:component-scan base-package="basePakage"/>@RequestMapping：注解类型映射的URI与方法( @RequestMapping(value="", method=RequestMethod.POST) )
@Controller
public class ProductController{
@RequestMapping("/input.do")
public String Input(){}
}@Autowired：利用@Autowired进行依赖注入到SpringMVC
@Controller
public class ProductController {
@Autowired
private BookService bs;
}@Service：注解此类是服务类（想要用@Autowired和@Service注解在配置文件中添加元素来扫描依赖基本包）
@Service
public class BookServiceimpl implements BookService{
bs.method(); //可以直接调用service接口，不用在实例化继承service接口的类
}@RequestParam：请求参数（String id = httpServletRequest.getParameter("id")） == (@RequestParam string id)
@ModelAttribute：带此注解的方***输入或创建的参数对象添加到Model对象中。输入或创建的Order实例将用newOrder键值添加到Model对象中。如果未定义键值名，则将使用改对象类型的名称。
@RequestMapping(method=RequestMethod.POST)
Public String sumitOrder(@ModelAttribute("newOrder") Order order,Model model){}
or
public String submitOrder(@ModelAttribute Order order, Model model)第二个用途是标注一个非请求的处理方法。被@ModelAttribute注解的方***在每次调用该控制器类的请求处理方法时被调用。Spring MVC在会调用请求处理方法之前调用带@ModelAttribute注解的方法。@ModelAttribute注解的方法可以返回一个对象或一个void类型。如果返回一个对象，则返回对象会自动添加到Model中。如果返回void需要添加Model类型参数，并自行将实例添加到Model中。
@ModelAttribute
public Product addProduct(@RequestParam String productId) {
return productService.get(productId);
}
or
@ModelAttribute
public void addProduct(@RequestParam String id, Model model) {
model.addAttribute(new Account(id));
}程序
应用上述注解在下列程序中应用，此应用程序拥有添加，查看，编辑图书功能
拥有两个javaBean类Book.java和Product.java类
Book.java
package domain;
import java.io.Serializable;
import java.math.BigDecimal;
public class Book implements Serializable {
private static final long seriaVersionUID = 1L;
private long id;
private String isbn;
private String title;
private Category category;
private String author;
private BigDecimal price;
public Book() {}
public Book(long id, String isbn, String title,
Category category, String author, BigDecimal price) {
this.id = id;
this.isbn = isbn;
this.title = title;
this.category = category;
this.author = author;
this.price = price;
}
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;
}
public BigDecimal getPrice() {
return price;
}
public void setPrice(BigDecimal price) {
this.price = price;
}
}
***Category.java***package domain;
import java.io.Serializable;
public class Category implements Serializable {
private static final long serialVersionUID = 1L;
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;
}}
***BookController.java控制器***
package 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 domain.Book;
import domain.Category;
import service.BookService;
@Controller
public class BookController {
@Autowired
private BookService bookService;
private static final Log logger = LogFactory.getLog(BookController.class);
@RequestMapping("/input-book")
public String inputBook(Model model) {
List categories = bookService.getAllCategories();
model.addAttribute("categories", categories);
model.addAttribute("book", new Book());
return "BookAddForm";
}
@RequestMapping("/edit-book/{id}")
public String editBook(Model model, @PathVariable long id) {
List categories = bookService.getAllCategories();
model.addAttribute("categories", categories);
Book book = bookService.get(id);
model.addAttribute("book", book);
return "BookEditForm";
}
@RequestMapping("/save-book")
public String saveBook(@ModelAttribute Book book) {
Category category = bookService.getCategory(book.getCategory().getId());
book.setCategory(category);
bookService.save(book);
return "redirect:/list-book";
}
@RequestMapping("/update-book")
public String updateBook(@ModelAttribute Book book) {
Category category =
bookService.getCategory(book.getCategory().getId());
book.setCategory(category);
bookService.update(book);
return "redirect:/list-book";
}
@RequestMapping("/list-book")
public String listBooks(Model model) {
logger.info("listBooks");
List books = bookService.getAllBooks();
model.addAttribute("books", books);
return "BookList";
}}
***BookService.java接口***
package service;
import java.util.List;
import domain.Category;
import domain.Book;
public inter***Service {
List getAllCategories(); Category getCategory(int id); List getAllBooks(); Book save(Book book); Book update(Book book); Book get(long id); long getNextId();
}
***BookServiceimpl.java实现接口类***
package service;
import java.math.BigDecimal;
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{
private List categories;
private List books;
public BookServiceImpl() {
categories = new ArrayList();
Category category1 = new Category(1,"计算机");
Category category2 = new Category(2,"旅游");
Category category3 = new Category(3,"教育");
categories.add(category1);
categories.add(category2);
categories.add(category3);
books = new ArrayList();
books.add(new Book(1L, "9781771970273", "Servlet",
category1, "segnwu", new BigDecimal("99.99")));
books.add(new Book(2L, "9781771970297", "c++",
category1, "son", new BigDecimal("99.99")));
}
@Override
public List getAllCategories() {
return categories;
}
@Override
public Category getCategory(int id) {
for(Category category : categories) {
if(id == category.getId()) {
return category;
}
}
return null;
}
@Override
public List getAllBooks() {
return books;
}
@Override
public Book save(Book book) {
book.setId(getNextId());
books.add(book);
return book;
}
@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 Book get(long id) {
for(Book book : books) {
if (id == book.getId()) {
return book;
}
}
return null;
}
@Override
public long getNextId() {
long id = 0L;
for(Book book : books) {
long bookId = book.getId();
if(bookId > id) {
id = bookId;
}
}
return id + 1;
}
}
此应用程序的文件目录结构为如下
实现效果为
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