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八、RESTful案例
1、准备工作
和传统 CRUD 一样，实现对员工信息的增删改查。
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搭建环境
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准备实体类
package com.atguigu.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(Integer id, String lastName, String email, Integer gender) { super(); this.id = id; this.lastName = lastName; this.email = email; this.gender = gender; } public Employee() { } } -
准备dao模拟数据
package com.atguigu.mvc.dao; import java.util.Collection; import java.util.HashMap; import java.util.Map; import com.atguigu.mvc.bean.Employee; import org.springframework.stereotype.Repository; @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); } }
2、功能清单
| 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 |
3、具体功能：访问首页
a>配置view-controller
<mvc:view-controller path="/" view-name="index"/>
b>创建页面
<!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、具体功能：查询所有员工数据
a>控制器方法
@RequestMapping(value = "/employee", method = RequestMethod.GET)
public String getEmployeeList(Model model){
Collection<Employee> employeeList = employeeDao.getAll();
model.addAttribute("employeeList", employeeList);
return "employee_list";
}
b>创建employee_list.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Employee Info</title>
<script type="text/javascript" th:src="@{/static/js/vue.js}"></script>
</head>
<body>
<table border="1" cellpadding="0" cellspacing="0" style="text-align: center;" id="dataTable">
<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/'+${employee.id}}">update</a>
</td>
</tr>
</table>
</body>
</html>
5、具体功能：删除
a>创建处理delete请求方式的表单
<!-- 作用：通过超链接控制表单的提交，将post请求转换为delete请求 -->
<form id="delete_form" method="post">
<!-- HiddenHttpMethodFilter要求：必须传输_method请求参数，并且值为最终的请求方式 -->
<input type="hidden" name="_method" value="delete"/>
</form>
b>删除超链接绑定点击事件
引入vue.js
<script type="text/javascript" th:src="@{/static/js/vue.js}"></script>
删除超链接
<a class="deleteA" @click="deleteEmployee" th:href="@{'/employee/'+${employee.id}}">delete</a>
通过vue处理点击事件
<script type="text/javascript">
var vue = new Vue({
el:"#dataTable",
methods:{
//event表示当前事件
deleteEmployee:function (event) {
//通过id获取表单标签
var delete_form = document.getElementById("delete_form");
//将触发事件的超链接的href属性为表单的action属性赋值
delete_form.action = event.target.href;
//提交表单
delete_form.submit();
//阻止超链接的默认跳转行为
event.preventDefault();
}
}
});
</script>
c>控制器方法
@RequestMapping(value = "/employee/{id}", method = RequestMethod.DELETE)
public String deleteEmployee(@PathVariable("id") Integer id){
employeeDao.delete(id);
return "redirect:/employee";
}
6、具体功能：跳转到添加数据页面
a>配置view-controller
<mvc:view-controller path="/toAdd" view-name="employee_add"></mvc:view-controller>
b>创建employee_add.html
<!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
<input type="radio" name="gender" value="0">female<br>
<input type="submit" value="add"><br>
</form>
</body>
</html>
7、具体功能：执行保存
a>控制器方法
@RequestMapping(value = "/employee", method = RequestMethod.POST)
public String addEmployee(Employee employee){
employeeDao.save(employee);
return "redirect:/employee";
}
8、具体功能：跳转到更新数据页面
a>修改超链接
<a th:href="@{'/employee/'+${employee.id}}">update</a>
b>控制器方法
@RequestMapping(value = "/employee/{id}", method = RequestMethod.GET)
public String getEmployeeById(@PathVariable("id") Integer id, Model model){
Employee employee = employeeDao.get(id);
model.addAttribute("employee", employee);
return "employee_update";
}
c>创建employee_update.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Update Employee</title>
</head>
<body>
<form th:action="@{/employee}" method="post">
<input type="hidden" name="_method" value="put">
<input type="hidden" name="id" th:value="${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>
9、具体功能：执行更新
a>控制器方法
@RequestMapping(value = "/employee", method = RequestMethod.PUT)
public String updateEmployee(Employee employee){
employeeDao.save(employee);
return "redirect:/employee";
}
八、HttpMessageConverter
HttpMessageConverter，报文信息转换器，将请求报文转换为Java对象，或将Java对象转换为响应报文
HttpMessageConverter提供了两个注解和两个类型：@RequestBody，@ResponseBody，RequestEntity，
ResponseEntity
1、@RequestBody
@RequestBody可以获取请求体，需要在控制器方法设置一个形参，使用@RequestBody进行标识，当前请求的请求体就会为当前注解所标识的形参赋值
<form th:action="@{/testRequestBody}" method="post">
用户名：<input type="text" name="username"><br>
密码：<input type="password" name="password"><br>
<input type="submit">
</form>
@RequestMapping("/testRequestBody")
public String testRequestBody(@RequestBody String requestBody){
System.out.println("requestBody:"+requestBody);
return "success";
}
输出结果：
requestBody:username=admin&password=123456
2、RequestEntity
RequestEntity封装请求报文的一种类型，需要在控制器方法的形参中设置该类型的形参，当前请求的请求报文就会赋值给该形参，可以通过getHeaders()获取请求头信息，通过getBody()获取请求体信息
@RequestMapping("/testRequestEntity")
public String testRequestEntity(RequestEntity<String> requestEntity){
System.out.println("requestHeader:"+requestEntity.getHeaders());
System.out.println("requestBody:"+requestEntity.getBody());
return "success";
}
输出结果： requestHeader:[host:"localhost:8080", connection:"keep-alive", content-length:"27", cache-control:"max-age=0", sec-ch-ua:"" Not A;Brand";v="99", "Chromium";v="90", "Google Chrome";v="90"", sec-ch-ua-mobile:"?0", upgrade-insecure-requests:"1", origin:"http://localhost:8080", user-agent:"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36"] requestBody:username=admin&password=123
3、@ResponseBody
@ResponseBody用于标识一个控制器方法，可以将该方法的返回值直接作为响应报文的响应体响应到浏览器
@RequestMapping("/testResponseBody")
@ResponseBody
public String testResponseBody(){
return "success";
}
结果：浏览器页面显示success
4、SpringMVC处理json
@ResponseBody处理json的步骤：
a>导入jackson的依赖
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.12.1</version>
</dependency>
b>在SpringMVC的核心配置文件中开启mvc的注解驱动，此时在HandlerAdaptor中会自动装配一个消息转换器：MappingJackson2HttpMessageConverter，可以将响应到浏览器的Java对象转换为Json格式的字符串
<mvc:annotation-driven />
c>在处理器方法上使用@ResponseBody注解进行标识
d>将Java对象直接作为控制器方法的返回值返回，就会自动转换为Json格式的字符串
@RequestMapping("/testResponseUser")
@ResponseBody
public User testResponseUser(){
return new User(1001,"admin","123456",23,"男");
}
浏览器的页面中展示的结果：
{"id":1001,"username":"admin","password":"123456","age":23,"sex":"男"}
5、SpringMVC处理ajax
a>请求超链接：
<div id="app">
<a th:href="@{/testAjax}" @click="testAjax">testAjax</a><br>
</div>
b>通过vue和axios处理点击事件：
<script type="text/javascript" th:src="@{/static/js/vue.js}"></script>
<script type="text/javascript" th:src="@{/static/js/axios.min.js}"></script>
<script type="text/javascript">
var vue = new Vue({
el:"#app",
methods:{
testAjax:function (event) {
axios({
method:"post",
url:event.target.href,
params:{
username:"admin",
password:"123456"
}
}).then(function (response) {
alert(response.data);
});
event.preventDefault();
}
}
});
</script>
c>控制器方法：
@RequestMapping("/testAjax")
@ResponseBody
public String testAjax(String username, String password){
System.out.println("username:"+username+",password:"+password);
return "hello,ajax";
}
6、@RestController注解
@RestController注解是springMVC提供的一个复合注解，标识在控制器的类上，就相当于为类添加了@Controller注解，并且为其中的每个方法添加了@ResponseBody注解
7、ResponseEntity
ResponseEntity用于控制器方法的返回值类型，该控制器方法的返回值就是响应到浏览器的响应报文
