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