文章目录
- 前言
- 一、RESTful简介
- 二、RESTful的实现
- 三、HiddenHttpMethodFilter
- 四、源码实例
- 1.工程文件图
- 2.Employee实体类
- 2.dao层:EmployeeDao类
- 3.首页:index.html
- 4.控制层:EmployeeController类
- 5.employee_add.html页面
- 6.employee_list.html页面
- 7.employee_update.html页面
- 8.web.xml
- 9.springMVC.xml
- 总结
前言
RESTful
一、RESTful简介
REST:Representational State Transfer,表现层资源状态转移。
- 资源
资源是一种看待服务器的方式,即,将服务器看作是由很多离散的资源组成。每个资源是服务器上一个可命名的抽象概念。因为资源是一个抽象的概念,所以它不仅仅能代表服务器文件系统中的一个文件、数据库中的一张表等等具体的东西,可以将资源设计的要多抽象有多抽象,只要想象力允许而且客户端应用开发者能够理解。与面向对象设计类似,资源是以名词为核心来组织的,首先关注的是名词。一个资源可以由一个或多个URI来标识。URI既是资源的名称,也是资源在Web上的地址。对某个资源感兴趣的客户端应用,可以通过资源的URI与其进行交互。 - 资源的表述
资源的表述是一段对于资源在某个特定时刻的状态的描述。可以在客户端-服务器端之间转移(交换)。资源的表述可以有多种格式,例如HTML/XML/JSON/纯文本/图片/视频/音频等等。资源的表述格式可以通过协商机制来确定。请求-响应方向的表述通常使用不同的格式。 - 状态转移
状态转移说的是:在客户端和服务器端之间转移(transfer)代表资源状态的表述。通过转移和操作资源的表述,来间接实现操作资源的目的。
二、RESTful的实现
具体说,就是 HTTP 协议里面,四个表示操作方式的动词:GET、POST、PUT、DELETE。
它们分别对应四种基本操作:GET 用来获取资源
,POST 用来新建资源
,PUT 用来更新资源
,DELETE用来删除资源
。
REST 风格提倡 URL 地址使用统一的风格设计,从前到后各个单词使用斜杠分开,不使用问号键值对方式携带请求参数,而是将要发送给服务器的数据作为 URL 地址的一部分,以保证整体风格的一致性。
操作 | 传统方式 | REST风格 |
---|---|---|
查询操作 | getUserById?id=1 | user/1–>get请求方式 |
保存操作 | saveUser | user–>post请求方式 |
删除操作 | deleteUser?id=1 | user/1–>delete请求方式 |
更新操作 | updateUser | user–>put请求方式 |
三、HiddenHttpMethodFilter
由于浏览器只支持发送get和post方式的请求,那么该如何发送put和delete请求呢?
SpringMVC 提供了 HiddenHttpMethodFilter 帮助我们将 POST 请求转换为 DELETE
或 PUT
请求HiddenHttpMethodFilter 处理put和delete请求的条件:
- 当前请求的请求方式必须为post
- 当前请求必须传输请求参数_method
满足以上条件,HiddenHttpMethodFilter 过滤器就会将当前请求的请求方式转换为请求参数_method
的值,因此请求参数_method的值才是最终的请求方式。
在web.xml中注册HiddenHttpMethodFilter:
<filter>
<filter-name>HiddenHttpMethodFilter</filter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filterclass>
</filter>
<filter-mapping>
<filter-name>HiddenHttpMethodFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
注:
SpringMVC中提供了两个过滤器:CharacterEncodingFilter和HiddenHttpMethodFilter。在web.xml中注册时,必须先注册CharacterEncodingFilter,再注册HiddenHttpMethodFilter。
原因:
在 CharacterEncodingFilter 中通过request.setCharacterEncoding(encoding) 方法设置字
符集的request.setCharacterEncoding(encoding) 方法要求前面不能有任何获取请求参数的操作。
而 HiddenHttpMethodFilter 恰恰有一个获取请求方式的操作:
String paramValue = request.getParameter(this.methodParam);
四、源码实例
实现:和传统 CRUD 一样,实现对员工信息的增删改查。
功能 | URL地址 | 请求方式 |
---|---|---|
访问首页√ | / | GET |
查询全部数据√ | /employee | GET |
删除√ | /employee/2 | DELETE |
跳转到添加数据页面√ | /toAdd | GET |
执行保存√ | /employee | POST |
跳转到更新数据页面√ | /employee/2 | GET |
执行更新√ | /employee | PUT |
1.工程文件图
红框内是用到的文件,其他不需要管,注意文件夹结构。
2.Employee实体类
package com.dragon.mvc.bean;
public class Employee {
private Integer id;
private String lastName;
private String email;
//1 male, 0 female
private Integer gender;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Integer getGender() {
return gender;
}
public void setGender(Integer gender) {
this.gender = gender;
}
public Employee() {
}
public Employee(Integer id, String lastName, String email, Integer gender) {
this.id = id;
this.lastName = lastName;
this.email = email;
this.gender = gender;
}
}
2.dao层:EmployeeDao类
package com.dragon.mvc.dao;
import com.dragon.mvc.bean.Employee;
import org.springframework.stereotype.Repository;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
@Repository
public class EmployeeDao {
private static Map<Integer, Employee> employees = null;
static{
employees = new HashMap<Integer, Employee>();
employees.put(1001, new Employee(1001, "E-AA", "aa@163.com", 1));
employees.put(1002, new Employee(1002, "E-BB", "bb@163.com", 1));
employees.put(1003, new Employee(1003, "E-CC", "cc@163.com", 0));
employees.put(1004, new Employee(1004, "E-DD", "dd@163.com", 0));
employees.put(1005, new Employee(1005, "E-EE", "ee@163.com", 1));
}
private static Integer initId = 1006;
public void save(Employee employee){
if(employee.getId() == null){
employee.setId(initId++);
}
employees.put(employee.getId(), employee);
}
public Collection<Employee> getAll(){
return employees.values();
}
public Employee get(Integer id){
return employees.get(id);
}
public void delete(Integer id){
employees.remove(id);
}
}
3.首页:index.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8" >
<title>Title</title>
</head>
<body>
<h1>首页</h1>
<a th:href="@{/employee}">访问员工信息</a>
</body>
</html>
4.控制层:EmployeeController类
package com.dragon.mvc.controller;
import com.dragon.mvc.bean.Employee;
import com.dragon.mvc.dao.EmployeeDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import java.util.Collection;
@Controller
public class EmployeeController {
@Autowired
private EmployeeDao employeeDao;
@RequestMapping(value = "/employee",method = RequestMethod.GET)
public String getAllEmpolyee(Model model){
Collection<Employee> employeelist=employeeDao.getAll();
model.addAttribute("employeelist",employeelist);
return "employee_list";
}
@RequestMapping(value = "/employee/{id}", method = RequestMethod.DELETE)
public String deleteEmployee(@PathVariable("id") Integer id){
employeeDao.delete(id);
return "redirect:/employee";
}
@RequestMapping(value = "/employee", method = RequestMethod.POST)
public String addEmployee(Employee employee){
employeeDao.save(employee);
return "redirect:/employee";
}
@RequestMapping(value = "/employee/{id}", method = RequestMethod.GET)
public String getEmployeeById(@PathVariable("id") Integer id, Model model){
Employee employee = employeeDao.get(id);
model.addAttribute("employee", employee);
return "employee_update";
}
@RequestMapping(value = "/employee", method = RequestMethod.PUT)
public String updateEmployee(Employee employee){
employeeDao.save(employee);
return "redirect:/employee";
}
}
5.employee_add.html页面
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>add employee</title>
</head>
<body>
<form th:action="@{/employee}" method="post">
lastName:<input type="text" name="lastName"><br>
email:<input type="text" name="email"><br>
gender:<input type="radio" name="gender" value="1">male<br>
<input type="radio" name="gender" value="0">female<br>
<input type="submit" value="add">
</form>
</body>
</html>
6.employee_list.html页面
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Employee info</title>
</head>
<body>
<table id="dataTable" border="1" cellspacing="0" style="text-align: center">
<tr>
<th colspan="5">Employee Info</th>
</tr>
<tr>
<th>id</th>
<th>lastname</th>
<th>email</th>
<th>gender</th>
<th>options (<a th:href="@{/toAdd}">add</a>)</th>
</tr>
<tr th:each="employee : ${employeelist}">
<td th:text="${employee.id}"></td>
<td th:text="${employee.lastName}"></td>
<td th:text="${employee.email}"></td>
<td th:text="${employee.gender}"></td>
<td>
<a class="deleteA" @click="deleteEmployee"
th:href="@{'/employee/'+${employee.id}}">delete</a>
<a th:href="@{'/employee/'+${employee.id}}">update</a>
</td>
</tr>
</table>
<form id="deleteForm" method="post">
<input type="hidden" name="_method" value="delete">
</form>
<script type="text/javascript" th:src="@{/static/js/vue.js}"></script>
<script type="text/javascript">
var vue=new Vue({
el:"#dataTable",
methods:{
deleteEmployee:function (event) {
var delete_form = document.getElementById("deleteForm");
delete_form.action = event.target.href;
delete_form.submit();
event.preventDefault();
}
}
});
</script>
</body>
</html>
7.employee_update.html页面
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Update Employee</title>
</head>
<body>
<form th:action="@{/employee}" method="post">
<input type="hidden" name="_method" value="put">
<input type="hidden" name="id" th:value="${employee.id}">
lastName:<input type="text" name="lastName" th:value="${employee.lastName}">
<br>
email:<input type="text" name="email" th:value="${employee.email}"><br>
<!--
th:field="${employee.gender}"可用于单选框或复选框的回显
若单选框的value和employee.gender的值一致,则添加checked="checked"属性
-->
gender:<input type="radio" name="gender" value="1"
th:field="${employee.gender}">male
<input type="radio" name="gender" value="0"
th:field="${employee.gender}">female<br>
<input type="submit" value="update"><br>
</form>
</body>
</html>
8.web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<!--
注册springMVC的前端控制器,对浏览器所发送的请求统一进行处理
在此配置下,springMVC的配置文件具有默认的位置和名称
默认的位置:WEB-INF
默认的名称:<servlet-name>-servlet.xml
若要为springMVC的配置文件设置自定义的位置和名称
需要在servlet标签中添加init-param
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springMVC.xml</param-value>
</init-param>
load-on-startup:将前端控制器DispatcherServlet的初始化时间提前到服务器启动时
-->
<servlet>
<servlet-name>springMVC</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springMVC.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springMVC</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<filter>
<filter-name>CharacterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>forceResponseEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>HiddenHttpMethodFilter</filter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>HiddenHttpMethodFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
9.springMVC.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:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--扫描控制层组件-->
<context:component-scan base-package="com.dragon.mvc"></context:component-scan>
<!-- 配置Thymeleaf视图解析器 -->
<bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
<property name="order" value="1"/>
<property name="characterEncoding" value="UTF-8"/>
<property name="templateEngine">
<bean class="org.thymeleaf.spring5.SpringTemplateEngine">
<property name="templateResolver">
<bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
<!-- 视图前缀 -->
<property name="prefix" value="/WEB-INF/templates/"/>
<!-- 视图后缀 -->
<property name="suffix" value=".html"/>
<property name="templateMode" value="HTML5"/>
<property name="characterEncoding" value="UTF-8" />
</bean>
</property>
</bean>
</property>
</bean>
<!-- 开放对静态资源的访问-->
<mvc:default-servlet-handler/>
<!--
path:设置处理的请求地址
view-name:设置请求地址所对应的视图名称
-->
<mvc:view-controller path="/" view-name="index"></mvc:view-controller>
<mvc:view-controller path="/toAdd" view-name="employee_add"></mvc:view-controller>
<mvc:annotation-driven />
</beans>
总结
以上就是RESTful的讲解。