员工管理信息系统springboot+mybatis整合项目

系统管理员 2023-10-09 17:33 18阅读 0赞

#### 员工管理信息系统springboot+mybatis整合项目 ####

*  1 导入资源
 *   *  1.1 依赖
     *  1.2 html页面
     *  1.3 Thymeleaf使用
 *  2 pojo
 *  3 Mapper
 *   *  3.1 DepartmentMapper
     *  3.2 EmployeeMapper
 *  4 Service
 *   *  4.1 DepartmentService/Impl
     *  4.2 EmployeeService/Impl
 *  5 页面国际化
 *   *  5.1 准备工作
     *  5.2 编写配置文件
     *  5.3 国际化解析组件
     *  5.4 配置页面国际化
 *  6 登录/登出
 *   *  6.1 登录
     *   *  6.1.1 前端页面
         *  6.1.2 Controller
     *  6.2 登出
     *  6.3 登录拦截器
 *  7 提取公共页面
 *  8 员工列表展示
 *   *  8.1 前端代码
     *  8.2 Controller
 *  9 员工CRUD
 *   *  9.1 增加员工
     *  9.2 删除员工
     *  9.3 修改员工
 *  10 拦截器
 *   *  10.1 登录拦截器
     *  10.2 命名变换

## 1 导入资源 ##

### 1.1 依赖 ###

<dependencies>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.3</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-jdbc</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-thymeleaf</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>com.mysql</groupId>
                <artifactId>mysql-connector-j</artifactId>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>

### 1.2 html页面 ###

页面资源在我的CSDN可以免费下载，地址如下：

下载链接: [员工管理系统静态资源(原版)][Link 1]

**注意:静态资源放入static和templates中**

导入静态页面，静态资源放入static和templates中

<link th:href="@{/css/bootstrap.min.css}" rel="stylesheet">
    <link th:href="@{/css/signin.css}" rel="stylesheet">
    
    
    <img class="mb-4" th:src="@{/img/bootstrap-solid.svg}" alt="" width="72" height="72">
    
    
    <script type="text/javascript" th:src="@{/js/jquery-3.2.1.slim.min.js}"></script>
    <script type="text/javascript" th:src="@{/js/popper.min.js}"></script>
    <script type="text/javascript" th:src="@{/js/bootstrap.min.js}"></script>
    <script type="text/javascript" th:src="@{/js/feather.min.js}"></script>
    <script type="text/javascript" th:src="@{/js/Chart.min.js}"></script>

### 1.3 Thymeleaf使用 ###

>  *  简单表达式
>     
>      *  变量表达式：**$\{…\}**
>      *  选择变量表达式：\***\{…\}**
>      *  信息表达式：**\#\{…\}**
>      *  链接URL表达式：**@\{…\}**
>      *  片段表达式：**~\{…\}**
>  *  常量
>     
>      *  文本常量：**‘example’，‘other example’，…**
>      *  号码常量：**1，12， 5.0，12.56，…**
>      *  布尔常量：**true，false**
>      *  空常量：**null**
>      *  常量标记：**one，sometext，other，…**
>  *  文本操作
>     
>      *  字符串串联：**+**
>      *  文字替换：**|hello，my name is $\{name\}|**
>  *  算术运算
>     
>      *  二元运算符：**+，-，\*，/，%**
>      *  减号（一元运算符）：**-**
>  *  布尔运算
>     
>      *  二元运算符：**and，or**
>      *  布尔否定（一元运算符）：**!，not**
>  *  比较和相等
>     
>      *  比较运算：**>，<，>=，<=，（gt，lt，ge，le）**
>      *  相等运算（一元运算符）**：==，!=，（eq，ne）**
>  *  条件运算符
>     
>      *  If-then：**(if) ? (then)**
>      *  If-then-else：**(if) ? (then) : (else)**
>      *  Default：**(value) ?: (defaultvalue)**
>  *  特殊令牌
>     
>      *  无操作：**\_**

## 2 pojo ##

导入lombok,自动写get/set方法

<dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>

> 注解：  
> @Data // 使用lombok  
> @AllArgsConstructor // 有参构造  
> @NoArgsConstructor // 无参构造

Department.java

package com.cycyong.pojo;
    import lombok.AllArgsConstructor;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    
    @Data // 使用lombok
    @AllArgsConstructor // 有参
    @NoArgsConstructor // 无参
    public class Department {
        
        private Integer id;
        private String departmentName;
    }

Emoloyee.java

package com.cycyong.pojo;
    import lombok.AllArgsConstructor;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    import java.util.Date;
    
    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class Employee {
        
        private Integer id;
        private String ename;
        private String email;
        private Integer gender;// 0是男，1是女
        private Integer did;
        private String dname;
        private Date birthday;
    }

## 3 Mapper ##

### 3.1 DepartmentMapper ###

DepartmentMapper.java

> 注解：
> 
>  *  @Mapper：表示这是一个Mybatis的Mapper类
>  *  @Repository：将Dao层的类标识为 Spring Bean

package com.cycyong.mapper;
    import com.cycyong.pojo.Department;
    import org.apache.ibatis.annotations.Mapper;
    import org.springframework.stereotype.Repository;
    import java.util.List;
    
    @Mapper
    @Repository
    public interface DepartmentMapper {
        
        // 获得部门列表
        public List<Department> getDepartmentList();
    
        // 根据ID得到部门
        public Department getDepartmentById(int id);
    }

Department.xml

### 3.2 EmployeeMapper ###

package com.cycyong.mapper;
    import com.cycyong.pojo.Employee;
    import org.apache.ibatis.annotations.Mapper;
    import org.springframework.stereotype.Repository;
    import java.util.List;
    @Repository
    @Mapper
    public interface EmployeeMapper {
        
        /**
         * 得到全部员工
         * @return list
         */
        public List<Employee> getEmployeeList();
    
        /**
         * 添加员工
         * @param employee 员工对象
         * @return int 影响行数
         */
        public int addEmployee(Employee employee);
    
        /**
         * 删除员工
         * @param id
         * @return
         */
        public int deleteEmployee(int id);
    
        /**
         * 修改员工
         * @param employee
         * @return
         */
        public int updateEmployee(Employee employee);
    
        /**
         * 按照id查找员工
         * @param id
         * @return
         */
        public Employee queryEmployeeById(int id);
    }

EmployeeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
    <mapper namespace="com.cycyong.mapper.UserMapper">
        <select id="queryUserList" resultType="com.cycyong.pojo.User">
            select * from mybatis.user
        </select>
        <select id="queryUserById"  parameterType="int" resultType="com.cycyong.pojo.User">
            select * from mybatis.user where id = #{id}
        </select>
        <insert id="addUser" parameterType="User">
            insert into mybatis.user (id, name, pwd) VALUES (#{id},#{name},#{pwd})
        </insert>
        <update id="updateUser" parameterType="User">
            UPDATE mybatis.user set name = #{name},pwd = #{pwd} where id = #{id}
        </update>
        <delete id="deleteUser" parameterType="int">
            delete from mybatis.user where id = #{id}
        </delete>
    </mapper>

## 4 Service ##

Service层调Dao层(Mapper)

> 注解：
> 
>  *  @Service：标记该类是一个service类，会将当前类自动注入到spring容器
>  *  @Autowired：可以标注在属性上、方法上和构造器上，来完成自动装配

### 4.1 DepartmentService/Impl ###

DepartmentService.java

package com.cycyong.service;
    import com.cycyong.pojo.Department;
    import java.util.List;
    public interface DepartmentService {
        
    
        public List<Department> getDepartmentList();
        
        public Department getDepartmentById(int id);
    }

DepartmentServiceImpl.java

package com.cycyong.service;
    
    import com.cycyong.mapper.DepartmentMapper;
    import com.cycyong.pojo.Department;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    
    @Service
    public class DepartmentServiceImpl implements DepartmentService {
        
        @Autowired
        DepartmentMapper departmentMapper;
        public void setDepartmentMapper(DepartmentMapper departmentMapper) {
        
            this.departmentMapper = departmentMapper;
        }
    
        @Override
        public List<Department> getDepartmentList() {
        
            return departmentMapper.getDepartmentList();
        }
    
        @Override
        public Department getDepartmentById(int id) {
        
    
            return departmentMapper.getDepartmentById(id);
        }
    }

### 4.2 EmployeeService/Impl ###

EmployeeService.java

package com.cycyong.service;
    
    import com.cycyong.pojo.Employee;
    
    import java.util.List;
    
    public interface EmployeeService {
        
    
        public List<Employee> getEmployeeList();
    
        public int addEmployee(Employee employee);
    
        public Employee queryEmployeeById(int id);
    
        public int updateEmployee(Employee employee);
    
        public int deleteEmployee(int id);
    }

EmployeeServiceImpl.java

package com.cycyong.service;
    import com.cycyong.mapper.EmployeeMapper;
    import com.cycyong.pojo.Employee;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import java.util.List;
    
    @Service
    public class EmployeeServiceImpl implements EmployeeService {
        
        @Autowired
        private EmployeeMapper employeeMapper;
    
        public void setEmployeeMapper(EmployeeMapper employeeMapper) {
        
            this.employeeMapper = employeeMapper;
        }
    
        @Override
        public List<Employee> getEmployeeList() {
        
            return employeeMapper.getEmployeeList();
        }
    
        @Override
        public int addEmployee(Employee employee) {
        
            return employeeMapper.addEmployee(employee);
        }
    
        @Override
        public Employee queryEmployeeById(int id) {
        
            return employeeMapper.queryEmployeeById(id);
        }
    
        @Override
        public int updateEmployee(Employee employee) {
        
            return employeeMapper.updateEmployee(employee);
        }
    
        @Override
        public int deleteEmployee(int id) {
        
            return employeeMapper.deleteEmployee(id);
        }
    }

## 5 页面国际化 ##

### 5.1 准备工作 ###

在IDEA中统一设置properties的编码问题！UTF-8  
![properties配置编码][properties]

### 5.2 编写配置文件 ###

*  第一步：在resource下创建i18n文件夹  
    ![在这里插入图片描述][c3f2dd6fe21f48729715dbc0e312090c.png]
 *  第二步：填写添加区域  
    ![在这里插入图片描述][8ca04313b92b4d7a88ddc20c1def6037.png]
 *  第三步：填写相关信息  
    ![在这里插入图片描述][d57fed0be1424c19a486c2b50148634a.png]

### 5.3 国际化解析组件 ###

根据按钮自动切换中文英文！  
在Spring中有一个国际化的Locale （区域信息对象）；里面有一个叫做`LocaleResolver` （获取区域信息对象）的解析器！

MyLocaleResolver.java

package com.cycyong.config;
    
    import org.springframework.web.servlet.LocaleContextResolver;
    import org.springframework.web.servlet.LocaleResolver;
    import org.thymeleaf.util.StringUtils;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.util.Locale;
    
    public class MyLocaleResolver implements LocaleResolver {
        
        // 解析请求
        @Override
        // 获得请求中的语言参数
        public Locale resolveLocale(HttpServletRequest request) {
        
            String language = request.getParameter("language");
            Locale locale = Locale.getDefault();//如果没有就是用默认的
    
            // 如果请求的链接携带了地区化的参数
            if(!StringUtils.isEmpty(language)){
        
                // zh_CN
                String[] split = language.split("_");
                // 国家，地区
                locale = new Locale(split[0], split[1]);
            }
            return locale;
        }
        @Override
        public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
        
    
        }
    }

在MyMvcConfig.java中装配  
自定义组件`MyLocaleResolver`注入bean中才能生效，即交给spring容器中进行管理

//自定义国际化组件就生效了
    @Bean//自动装配
    public LocaleResolver localeResolver(){
        
        return new MyLocaleResolver();
    }

配置基础路径  
如果不在`application`中进行配置路径则系统找不到  
application.properties

# 我们配置文件放在的真实位置
    spring.messages.basename=i18n.login

### 5.4 配置页面国际化 ###

> 取值为：\#\{…\}

<h1 class="h3 mb-3 font-weight-normal" th:text="#{login.tip}">Please sign in</h1>
    
    <input type="text" name="username" class="form-control" th:placeholder="#{login.username}" required="" autofocus="">
    
    <input type="password" name="password" class="form-control" th:placeholder="#{login.password}" required="">
    
    <input type="checkbox" value="remember-me" th:text="#{login.remember}">
    
    <button class="btn btn-lg btn-primary btn-block" type="submit"  th:text="#{login.btn}">Sign in</button>

![US][]  
![在这里插入图片描述][1402e61e163a47d4b45f486491733f2a.png]

## 6 登录/登出 ##

### 6.1 登录 ###

#### 6.1.1 前端页面 ####

`msg`为后端返回前端接收信息提示的标签

<!DOCTYPE html>
    <html lang="en" xmlns:th="http://www.thymeleaf.org">
    	<head>
    		<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    		<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    		<meta name="description" content="">
    		<meta name="author" content="">
    		<title>Signin Template for Bootstrap</title>
    		
    		<link th:href="@{/css/bootstrap.min.css}" rel="stylesheet">
    		
    		<link th:href="@{/css/signin.css}" rel="stylesheet">
    	</head>
    
    	<body class="text-center">
    		<form class="form-signin" th:action="@{/user/login}" method="post">
    			<img class="mb-4" th:src="@{/img/bootstrap-solid.svg}" alt="" width="72" height="72">
    			<p style="color: red" th:text="${msg}"></p>
    			<h1 class="h3 mb-3 font-weight-normal" th:text="#{login.tip}"></h1>
    			<input type="text" name="username" class="form-control" th:placeholder="#{login.username}" required="" autofocus="">
    			<input type="password" name="password" class="form-control" th:placeholder="#{login.password}" required="">
    			<div class="checkbox mb-3">
    				<label>
              <input type="checkbox" value="remember-me" th:text="#{login.remember}">
            </label>
    			</div>
    			<button class="btn btn-lg btn-primary btn-block" type="submit" th:text="#{login.btn}"></button>
    			<p class="mt-5 mb-3 text-muted">© 2017-2018</p>
    			<a class="btn btn-sm" th:href="@{/index.html(language='zh_CN')}">中文</a>
    			<a class="btn btn-sm" th:href="@{/index.html(language='en_US')}">English</a>
    		</form>
    	</body>
    </html>

#### 6.1.2 Controller ####

1.  控制层拿到`name`属性为`username`和`password`的两个值进行判断
2.  `password`正确之后创建用户`Session`，并重定向到主页
3.  `password`错误则用model返回报错信息

@RequestMapping("/user/login")
        public String login(@RequestParam("username") String username,
                            @RequestParam("password") String password,
                            HttpServletRequest request,
                            Model model){
        
            if(!StringUtils.isEmpty(username) && password.equals("123456")){
        
                // 登录成功，添加session
                request.getSession().setAttribute(Constants.LOGIN_SESSION,username);
                // 重定向到主页
                return "redirect:/main.html";
            }else{
        
                model.addAttribute("msg","用户名或密码错误！");
                return "index";
            }
        }

### 6.2 登出 ###

太简单了！直接将Session移除即可，在返回主页的过程中，登录拦截器`LoginHandlerInterceptor`会检测出`Session`是否存在!

@RequestMapping("/user/logout")
        public String logout(HttpServletRequest request){
        
            request.getSession().removeAttribute(Constants.LOGIN_SESSION);
            return "index";
        }

### 6.3 登录拦截器 ###

## 7 提取公共页面 ##

由于前端页面冗余代码太多，可以考虑代码复用  
Thymeleaf提供了`common`和`fragment`来进行复用，把公共部分提取出来

th:fragment="topbar"
    th:replace="~{common/commons::topbar}"

## 8 员工列表展示 ##

### 8.1 前端代码 ###

<!DOCTYPE html>
    
    <html lang="en" xmlns:th="http://www.thymeleaf.org">
    	<head>
    		<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    		<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    		<meta name="description" content="">
    		<meta name="author" content="">
    
    		<title>Dashboard Template for Bootstrap</title>
    		
    		<link th:href="@{/css/bootstrap.min.css}" rel="stylesheet">
    		
    		<link th:href="@{/css/dashboard.css}" rel="stylesheet">
    		<style type="text/css">
    			/* Chart.js */
    			@-webkit-keyframes chartjs-render-animation {
          
    				from {
          
    					opacity: 0.99
    				}
    				to {
          
    					opacity: 1
    				}
    			}	
    			@keyframes chartjs-render-animation {
          
    				from {
          
    					opacity: 0.99
    				}
    				to {
          
    					opacity: 1
    				}
    			}
    			
    			.chartjs-render-monitor {
          
    				-webkit-animation: chartjs-render-animation 0.001s;
    				animation: chartjs-render-animation 0.001s;
    			}
    		</style>
    	</head>
    
    	<body>
    		<div th:replace="~{common/commons::topbar}"></div>
    
    		<div class="container-fluid">
    			<div class="row">
    				
    				<div th:replace="~{common/commons::siderbar(active='list.html')}"></div>
    				<main role="main" class="col-md-9 ml-sm-auto col-lg-10 pt-3 px-4">
    					<h2><a class="btn btn-sm btn-success" th:href="@{/emp}">添加员工</a></h2>
    					<div class="table-responsive">
    						<table class="table table-striped table-sm">
    							<thead>
    								<tr>
    									<th>id</th>
    									<th>lastName</th>
    									<th>email</th>
    									<th>gender</th>
    									<th>department</th>
    									<th>date</th>
    									<th>操作</th>
    								</tr>
    							</thead>
    							<tbody>
    							<tr th:each="emp:${emps}">
    								<td th:text="${emp.getId()}"></td>
    								<td th:text="${emp.getEname()}"></td>
    								<td th:text="${emp.getEmail()}"></td>
    								<td th:text="${emp.getGender()==0?'男':'女'}"></td>
    								<td th:text="${emp.getDname()}"></td>
    								<td th:text="${#dates.format(emp.getBirthday(),'yyyy-MM-dd HH:mm:ss')}"></td>
    								<td>
    									<a class="btn btn-sm btn-primary" th:href="@{/toUpdateEmp/{id}(id=${emp.getId()})}">编辑</a>
    									<a class="btn btn-sm btn-danger" th:href="@{/deleteEmp/{id}(id=${emp.getId()})}">删除</a>
    								</td>
    							</tr>
    							</tbody>
    						</table>
    					</div>
    				</main>
    			</div>
    		</div>
    
    		
    		
    		<script type="text/javascript" th:src="@{/js/jquery-3.2.1.slim.min.js}"></script>
    		<script type="text/javascript" th:src="@{/js/popper.min.js}"></script>
    		<script type="text/javascript" th:src="@{/js/bootstrap.min.js}"></script>
    
    		
    		<script type="text/javascript" th:src="@{/js/feather.min.js}"></script>
    		<script>
    			feather.replace()
    		</script>
    
    		
    		<script type="text/javascript" th:src="@{/js/Chart.min.js}"></script>
    		<script>
    			var ctx = document.getElementById("myChart");
    			var myChart = new Chart(ctx, {
          
    				type: 'line',
    				data: {
          
    					labels: ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"],
    					datasets: [{
          
    						data: [15339, 21345, 18483, 24003, 23489, 24092, 12034],
    						lineTension: 0,
    						backgroundColor: 'transparent',
    						borderColor: '#007bff',
    						borderWidth: 4,
    						pointBackgroundColor: '#007bff'
    					}]
    				},
    				options: {
          
    					scales: {
          
    						yAxes: [{
          
    							ticks: {
          
    								beginAtZero: false
    							}
    						}]
    					},
    					legend: {
          
    						display: false,
    					}
    				}
    			});
    		</script>
    	</body>
    </html>

### 8.2 Controller ###

1.使用`model`将员工列表返回前端

@RequestMapping("/emps")
        public String List(Model model){
        
            List<Employee> employeeList = employeeService.getEmployeeList();
            model.addAttribute("emps",employeeList);
            return "emp/list";
        }

2.使用each将`emps`中的每一个员工对象遍历出来即可

<table class="table table-striped table-sm">
    	<thead>
    		<tr>
    			<th>id</th>
    			<th>lastName</th>
    			<th>email</th>
    			<th>gender</th>
    			<th>department</th>
    			<th>date</th>
    			<th>操作</th>
    		</tr>
    	</thead>
    	<tbody>
    	<tr th:each="emp:${emps}">
    		<td th:text="${emp.getId()}"></td>
    		<td th:text="${emp.getEname()}"></td>
    		<td th:text="${emp.getEmail()}"></td>
    		<td th:text="${emp.getGender()==0?'男':'女'}"></td>
    		<td th:text="${emp.getDname()}"></td>
    		<td th:text="${#dates.format(emp.getBirthday(),'yyyy-MM-dd HH:mm:ss')}"></td>
    		<td>
    			<a class="btn btn-sm btn-primary" th:href="@{/toUpdateEmp/{id}(id=${emp.getId()})}">编辑</a>
    			<a class="btn btn-sm btn-danger" th:href="@{/deleteEmp/{id}(id=${emp.getId()})}">删除</a>
    		</td>
    	</tr>
    	</tbody>
    </table>

3.操作部分的请求  
写法：

th:href="@{/toUpdateEmp/{id}(id=${emp.getId()})}"
    th:href="@{/deleteEmp/{id}(id=${emp.getId()})}"

## 9 员工CRUD ##

代码不一一展示了，有兴趣的可以在我的CSDN中查看源码：  
链接: [Java员工管理系统整合SpringBoot+mybatis实现完整版][Java_SpringBoot_mybatis]  
下面只讲解一些注意的地方：

### 9.1 增加员工 ###

添加员工的部门名的下拉列表必须先加载出来，修改员工也是如此

*  select的`name`属性为`did`
 *  用each遍历部门名
 *  `value`设置为部门`id`

<div class="form-group">
    	<label>department</label>
    	<select class="form-control" name="did">
    		<option th:each="dept:${departments}" th:text="${dept.getDname()}" th:value="${dept.getId()}"></option>
    	</select>
    </div>

### 9.2 删除员工 ###

@RequestMapping("/deleteEmp/{id}")
        public String deleteEmployee(@PathVariable("id") int id){
        
            employeeService.deleteEmployee(id);
            return "redirect:/emps";
        }

### 9.3 修改员工 ###

数据回显

@GetMapping("/toUpdateEmp/{id}")
        public String toUpdatePage(@PathVariable("id") int id,Model model){
        
            Employee employee = employeeService.queryEmployeeById(id);
            List<Department> departmentList = departmentService.getDepartmentList();
            System.out.println(employee);
            System.out.println(departmentList);
            model.addAttribute("employee",employee);
            model.addAttribute("departments",departmentList);
            return  "emp/update";
        }

修改

@RequestMapping("/updateEmp")
        public String UpdateEmployee(Employee employee){
        
            employeeService.updateEmployee(employee);
            return "redirect:/emps";
        }

## 10 拦截器 ##

### 10.1 登录拦截器 ###

登录拦截器`LoginHandlerInterceptor`实现`HandlerInterceptor`即可

`HandlerInterceptor`的三个方法:

public class LoginHandlerInterceptor implements HandlerInterceptor {
        
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        
        }

*  preHandle：在业务处理器处理请求之前被调用。预处理，可以进行编码、安全控制、权限校验等处理
 *  postHandle：在业务处理器处理请求执行完成后，生成视图之前执行。后处理（调用了Service并返回ModelAndView，但未进行页面渲染），有机会修改ModelAndView
 *  afterCompletion：在DispatcherServlet完全处理完请求后被调用，可用于清理资源等。返回处理（已经渲染了页面）

LoginHandlerInterceptor.java

1.  判断用户`session`是否存在
2.  不存在则请求转发回登录页面，并附上`msg`提示信息。不放行
3.  存在则放行即可

package com.cycyong.config;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    public class LoginHandlerInterceptor implements HandlerInterceptor {
        
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        
            // 判断有没有session即可
            Object attribute = request.getSession().getAttribute("loginUser");
            if (attribute==null){
        
                request.setAttribute("msg","没有权限，请先登录");
                request.getRequestDispatcher("/index.html").forward(request,response);
                return false;//不放行
            }else{
        
                return true;//放行
            }
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        
        }
    }

在同时也可排除某些方法或变量允许通过，新建一个配置类让他去实现`WebMvcConfigurer` ，并重写`addInterceptors`方法即可

// 自定义拦截器，并排除某些请求或资源
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
        
            registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
                    .excludePathPatterns("/index.html","/","/user/login","/css/**","/js/**",
                            "/img/**");
    //        registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**").
    //                excludePathPatterns("/index.html","/","/user/login","/static/**");
        }

### 10.2 命名变换 ###

在spring中，可能会有仅仅需要页面跳转而没有具体的业务逻辑的代码，如下所示  
我们点击前端某处的时候跳转到登录或者注册的HTML页面，但是controller方法都是空的，仅仅return了一个页面

@GetMapping("/login.html")
        public String loginPage(){
        
            return "login";
    }
    @GetMapping("/reg.html")
    public String regPage(){
        
        return "reg";
    }

长此以往我们的controller中会有很多这样的空方法，为了避免这种问题，我们使用SpringMVC中的`addViewController`来实现与上相同的逻辑。  
新建一个配置类让他去实现WebMvcConfigurer ，并重写`addViewController`方法，参数传入就是controller中的`url`，`setViewName`中传入的参数就是原return的页面。

@Configuration
    public class MyWebConfig implements WebMvcConfigurer {
        
        @Override
        public void addViewControllers(ViewControllerRegistry registry) {
        
            registry.addViewController("/login.html").setViewName("login");
            registry.addViewController("/reg.html").setViewName("reg");
        }
    }

**这样子更符合开发实际！**

[Link 1]: https://download.csdn.net/download/cycyong/87670414?spm=1001.2014.3001.5503
[properties]: https://img-blog.csdnimg.cn/17b0ced1de3b42488d12607d7653cd5c.png
[c3f2dd6fe21f48729715dbc0e312090c.png]: https://img-blog.csdnimg.cn/c3f2dd6fe21f48729715dbc0e312090c.png
[8ca04313b92b4d7a88ddc20c1def6037.png]: https://img-blog.csdnimg.cn/8ca04313b92b4d7a88ddc20c1def6037.png
[d57fed0be1424c19a486c2b50148634a.png]: https://img-blog.csdnimg.cn/d57fed0be1424c19a486c2b50148634a.png
[US]: https://img-blog.csdnimg.cn/cbbffcf7ae8f4fa0a0c5f325b5078ece.png
[1402e61e163a47d4b45f486491733f2a.png]: https://img-blog.csdnimg.cn/1402e61e163a47d4b45f486491733f2a.png
[Java_SpringBoot_mybatis]: https://download.csdn.net/download/cycyong/87697808