Restful 风格

大家在做Web开发的过程中，method常用的值是get和post. 可事实上，method值还可以是put和delete等等其他值。
既然method值如此丰富，那么就可以考虑使用同一个url，但是约定不同的method来实施不同的业务，这就是Restful的基本考虑。
CRUD是最常见的操作，在使用Restful 风格之前，通常的增加做法是这样的：

/addCategory?name=xxx

可是使用了Restful风格之后，增加就变成了：

/categories

CRUD如下表所示，URL就都使用一样的 "/categories"，区别只是在于method不同，服务器根据method的不同来判断浏览器期望做的业务行为

	传统风格		Restful风格
	url	method	url	method
增加	/addCategory?name=xxx	POST	/categories	POST
删除	/deleteCategory?id=123	GET	/categories/123	DELETE
修改	/updateCategory?id=123&name=yyy	POST	/categories/123	PUT
获取	/getCategory?id=123	GET	/categories/123	GET
查询	/listCategory	GET	/categories	GET

下面是jsp中的实例：

listCategory.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8"%>

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

<script type="text/javascript" src="js/jquery.min.js"></script>

<script type="text/javascript">
    /*将post method 改变为delete*/
    $(function(){
        $(".delete").click(function(){
            var href=$(this).attr("href");
            $("#formdelete").attr("action",href).submit();
            return false;
        })
    })
</script>

<div align="center">

</div>

<div style="width:500px;margin:20px auto;text-align: center">
    <table align='center' border='1' cellspacing='0'>
        <tr>
            <td>id</td>
            <td>name</td>
            <td>编辑</td>
            <td>删除</td>
        </tr>
        <c:forEach items="${page.content}" var="c" varStatus="st">
            <tr>
                <td>${c.id}</td>
                <td>${c.name}</td>
                <td><a href="categories/${c.id}">编辑</a></td>
                <td><a class="delete" href="categories/${c.id}">删除</a></td>
            </tr>
        </c:forEach>

    </table>
    <br>
    <div>
        <a href="?start=0">[首  页]</a>
        <a href="?start=${page.number-1}">[上一页]</a>
        <a href="?start=${page.number+1}">[下一页]</a>
        <a href="?start=${page.totalPages-1}">[末  页]</a>
    </div>
    <br>
    <form action="categories" method="post">
        name: <input name="name"> <br>
        <button type="submit">提交</button>

    </form>

    <form id="formdelete" action="" method="POST" >
        <input type="hidden" name="_method" value="DELETE">
    </form>
</div>

editCategory.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
 pageEncoding="UTF-8" isELIgnored="false"%>

<div style="margin:0px auto; width:500px">

<form action="../categories/${c.id}" method="post">
        <input type="hidden" name="_method" value="PUT">
name: <input name="name" value="${c.name}"> <br>
<button type="submit">提交</button>

</form>
</div>

CategoryController中的写法：

package com.how2java.springboot.web;

import com.how2java.springboot.dao.CategoryDAO;
import com.how2java.springboot.pojo.Category;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@Controller
public class CategoryController {
    @Autowired CategoryDAO categoryDAO;

    @GetMapping("/categories")
    public String listCategory(Model m, @RequestParam(value = "start", defaultValue = "0") int start, @RequestParam(value = "size", defaultValue = "5") int size) throws Exception {
        start = start<0?0:start;
        Sort sort = new Sort(Sort.Direction.DESC, "id");
        Pageable pageable = new PageRequest(start, size, sort);
        Page<Category> page =categoryDAO.findAll(pageable);
        m.addAttribute("page", page);
        return "listCategory";
    }

    @PostMapping("/categories")
    public String addCategory(Category c) throws Exception {
        categoryDAO.save(c);
        return "redirect:/categories";
    }
    @DeleteMapping("/categories/{id}")
    public String deleteCategory(Category c) throws Exception {
        categoryDAO.delete(c);
        return "redirect:/categories";
    }
    @PutMapping("/categories/{id}")
    public String updateCategory(Category c) throws Exception {
        categoryDAO.save(c);
        return "redirect:/categories";
    }
    @GetMapping("/categories/{id}")
    public String getCategory(@PathVariable("id") int id,Model m) throws Exception {
        Category c= categoryDAO.getOne(id);
        m.addAttribute("c", c);
        return "editCategory";
    }
}