SpringBoot整合SpringMVC、持久层技术MyBatis-程序员宅基地

1、通过使用SpringBoot、SpringMVC、MyBatis整合，实现一个对数据库中的数据表的增加、修改、删除、查询操作。

首先说明一下，这里使用的是Springboot2.2.6.RELEASE版本，由于Springboot迭代很快，所以要注意版本问题。

在pom文件中新增依赖包，如下所示：

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 4     <modelVersion>4.0.0</modelVersion>
 5     <parent>
 6         <groupId>org.springframework.boot</groupId>
 7         <artifactId>spring-boot-starter-parent</artifactId>
 8         <version>2.2.6.RELEASE</version>
 9         <relativePath/> <!-- lookup parent from repository -->
10     </parent>
11     <groupId>com.bie</groupId>
12     <artifactId>springboot-hello</artifactId>
13     <version>0.0.1-SNAPSHOT</version>
14     <name>springboot-hello</name>
15     <description>Demo project for Spring Boot</description>
16 
17     <properties>
18         <java.version>1.8</java.version>
19     </properties>
20 
21     <dependencies>
22         <dependency>
23             <groupId>org.springframework.boot</groupId>
24             <artifactId>spring-boot-starter-web</artifactId>
25         </dependency>
26         <dependency>
27             <groupId>org.springframework.boot</groupId>
28             <artifactId>spring-boot-starter-test</artifactId>
29             <scope>test</scope>
30             <exclusions>
31                 <exclusion>
32                     <groupId>org.junit.vintage</groupId>
33                     <artifactId>junit-vintage-engine</artifactId>
34                 </exclusion>
35             </exclusions>
36         </dependency>
37         <!-- thymeleaf的启动器 -->
38         <dependency>
39             <groupId>org.springframework.boot</groupId>
40             <artifactId>spring-boot-starter-thymeleaf</artifactId>
41         </dependency>
42         <!-- mybatis的启动器 -->
43         <dependency>
44             <groupId>org.mybatis.spring.boot</groupId>
45             <artifactId>mybatis-spring-boot-starter</artifactId>
46             <version>2.1.1</version>
47         </dependency>
48         <!-- mysql数据库驱动的依赖包 -->
49         <dependency>
50             <groupId>mysql</groupId>
51             <artifactId>mysql-connector-java</artifactId>
52         </dependency>
53         <!-- druid数据库连接池 -->
54         <dependency>
55             <groupId>com.alibaba</groupId>
56             <artifactId>druid</artifactId>
57             <version>1.1.10</version>
58         </dependency>
59     </dependencies>
60 
61     <build>
62         <plugins>
63             <plugin>
64                 <groupId>org.springframework.boot</groupId>
65                 <artifactId>spring-boot-maven-plugin</artifactId>
66             </plugin>
67         </plugins>
68     </build>
69 
70 </project>

配置application.properties全局配置文件。

 1 # 配置端口号8080,默认都是8080
 2 server.port=8080
 3 server.address=127.0.0.1
 4 
 5 # 数据库驱动,Springboot2.2.6.RELEASE版本
 6 spring.datasource.driver-class-name=com.mysql.jdbc.Driver
 7 # 数据库链接URL,Springboot2.2.6.RELEASE版本
 8 spring.datasource.url=jdbc:mysql://localhost:3306/biehl
 9 # 数据库账号,Springboot2.2.6.RELEASE版本
10 spring.datasource.username=root
11 # 数据库密码,Springboot2.2.6.RELEASE版本
12 spring.datasource.password=123456
13 
14 # 配置druid数据库连接池,数据源的类型
15 spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
16 
17 # 配置mybatis访问实体类的别名,起别名
18 mybatis.type-aliases-package=com.bie.springboothello.po

数据库表设计，简单的创建一个users数据表。

 1 /*
 2  Navicat Premium Data Transfer
 3 
 4  Source Server         : localhost
 5  Source Server Type    : MySQL
 6  Source Server Version : 50724
 7  Source Host           : localhost:3306
 8  Source Schema         : biehl
 9 
10  Target Server Type    : MySQL
11  Target Server Version : 50724
12  File Encoding         : 65001
13 
14  Date: 11/05/2020 12:13:21
15 */
16 
17 SET NAMES utf8mb4;
18 SET FOREIGN_KEY_CHECKS = 0;
19 
20 -- ----------------------------
21 -- Table structure for users
22 -- ----------------------------
23 DROP TABLE IF EXISTS `users`;
24 CREATE TABLE `users`  (
25   `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '用户编号',
26   `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '用户账号',
27   `age` int(11) DEFAULT NULL COMMENT '用户年龄',
28   PRIMARY KEY (`id`) USING BTREE
29 ) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_general_ci COMMENT = '用户表' ROW_FORMAT = Dynamic;
30 
31 SET FOREIGN_KEY_CHECKS = 1;

创建实体类Users。

 1 package com.bie.springboothello.po;
 2 
 3 public class Users {
 4 
 5     private int id;
 6     private String name;
 7     private int age;
 8 
 9     public int getId() {
10         return id;
11     }
12 
13     public void setId(int id) {
14         this.id = id;
15     }
16 
17     public String getName() {
18         return name;
19     }
20 
21     public void setName(String name) {
22         this.name = name;
23     }
24 
25     public int getAge() {
26         return age;
27     }
28 
29     public void setAge(int age) {
30         this.age = age;
31     }
32 
33     @Override
34     public String toString() {
35         return "Users{
    " +
36                 "id=" + id +
37                 ", name='" + name + '\'' +
38                 ", age=" + age +
39                 '}';
40     }
41 
42     public Users(int id, String name, int age) {
43         this.id = id;
44         this.name = name;
45         this.age = age;
46     }
47 }

创建 mapper 接口以及映射配置文件。

 1 package com.bie.springboothello.mapper;
 2 
 3 import com.bie.springboothello.po.Users;
 4 import org.springframework.stereotype.Repository;
 5 
 6 import java.util.List;
 7 
 8 /**
 9  *
10  */
11 @Repository // 在启动类里面，如果开启@MapperScan注解。
12 public interface UsersMapper {
13 
14     /**
15      * 插入用户信息
16      *
17      * @param users
18      */
19     public void insertUser(Users users);
20 
21     /**
22      * 查询所有的用户信息
23      *
24      * @return
25      */
26     public List<Users> selectUsersAll();
27 
28     /**
29      * 根据用户的编号进行查询
30      *
31      * @param id
32      * @return
33      */
34     public Users selectUsersById(Integer id);
35 
36 
37     /**
38      * 修改用户信息
39      *
40      * @param users
41      */
42     public void updateUser(Users users);
43 
44     /**
45      * 根据用户的编号进行删除操作
46      *
47      * @param id
48      */
49     public void deleteUserById(Integer id);
50 }

映射配置文件，如下所示，出现的问题在后面进行描述。

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <!-- namespace的值必须和Mapper的接口名称相同 -->
 6 <mapper namespace="com.bie.springboothello.mapper.UsersMapper">
 7 
 8     <!-- id必须和UsersMapper接口里面的方法名称相同 -->
 9     <!-- 由于在application.properties配置了mybatis.type-aliases-package别名，所以这里直接使用实体类名称即可 -->
10 
11     <!-- 插入用户信息 -->
12     <insert id="insertUser" parameterType="users">
13         insert into users(name,age) values(#{name},#{age})
14     </insert>
15 
16     <!-- 查询所有的用户信息 -->
17     <select id="selectUsersAll" resultType="users">
18         select id,name,age from users
19     </select>
20 
21     <!-- 根据用户的编号进行查询 -->
22     <select id="selectUsersById" resultType="users">
23         select id,name,age from users where id = #{value}
24     </select>
25 
26     <!-- 修改用户信息 -->
27     <update id="updateUser" parameterType="users">
28         update users set name=#{name} ,age=#{age} where id=#{id}
29     </update>
30 
31     <!-- 根据用户的编号进行删除操作 -->
32     <delete id="deleteUserById">
33         delete from users where id = #{value}
34     </delete>
35 </mapper>

创建业务层接口和业务层接口实现类。

 1 package com.bie.springboothello.service;
 2 
 3 import com.bie.springboothello.po.Users;
 4 
 5 import java.util.List;
 6 
 7 /**
 8  *
 9  */
10 public interface UsersService {
11 
12     /**
13      * 插入用户信息
14      *
15      * @param users
16      */
17     public void addUser(Users users);
18 
19     /**
20      * 查询所有的用户信息
21      *
22      * @return
23      */
24     public List<Users> findUserAll();
25 
26     /**
27      * 根据用户的编号进行查询
28      *
29      * @param id
30      * @return
31      */
32     public Users findUserById(Integer id);
33 
34     /**
35      * 修改用户信息
36      *
37      * @param users
38      */
39     public void updateUser(Users users);
40 
41     /**
42      * 根据用户的编号进行删除操作
43      *
44      * @param id
45      */
46     public void deleteUserById(Integer id);
47 }

业务层接口实现类。

 1 package com.bie.springboothello.service.impl;
 2 
 3 import com.bie.springboothello.mapper.UsersMapper;
 4 import com.bie.springboothello.po.Users;
 5 import com.bie.springboothello.service.UsersService;
 6 import org.springframework.beans.factory.annotation.Autowired;
 7 import org.springframework.stereotype.Service;
 8 import org.springframework.transaction.annotation.Transactional;
 9 
10 import java.util.List;
11 
12 @Service // 注入到Spring的bean容器中
13 @Transactional // 开启事务,该类下的所有方法都受事务控制
14 public class UsersServiceImpl implements UsersService {
15 
16     @Autowired // 依赖注入
17     private UsersMapper usersMapper;
18 
19     @Override
20     public void addUser(Users users) {
21         this.usersMapper.insertUser(users);
22     }
23 
24     @Override
25     public List<Users> findUserAll() {
26         return this.usersMapper.selectUsersAll();
27     }
28 
29     @Override
30     public Users findUserById(Integer id) {
31         return this.usersMapper.selectUsersById(id);
32     }
33 
34     @Override
35     public void updateUser(Users users) {
36         this.usersMapper.updateUser(users);
37     }
38 
39     @Override
40     public void deleteUserById(Integer id) {
41         this.usersMapper.deleteUserById(id);
42     }
43 
44 }

创建控制层。

  1 package com.bie.springboothello.controller;
  2 
  3 import com.bie.springboothello.po.Users;
  4 import com.bie.springboothello.service.UsersService;
  5 import org.springframework.beans.factory.annotation.Autowired;
  6 import org.springframework.stereotype.Controller;
  7 import org.springframework.ui.Model;
  8 import org.springframework.web.bind.annotation.PathVariable;
  9 import org.springframework.web.bind.annotation.RequestMapping;
 10 import org.springframework.web.bind.annotation.ResponseBody;
 11 
 12 import java.util.List;
 13 
 14 @Controller
 15 @RequestMapping(value = "/users")
 16 public class UsersController {
 17 
 18     @Autowired
 19     private UsersService usersService;
 20 
 21     @RequestMapping(value = "/hello")
 22     @ResponseBody
 23     public String showUser(Model model) {
 24         return "hello";
 25     }
 26 
 27     /**
 28      * 页面跳转
 29      * <p>
 30      * <p>
 31      * thymeleaf框架，模板级的视图层技术，需要放到classpath的根目录下，也就是src/main/resources下面的一个包叫做templates的目录下面
 32      *
 33      * <p>
 34      * <p>
 35      * 由于templates目录是安全的，不允许直接被外界访问的，所以将视图放到这里面之后，必须有Controller里面的方法
 36      * 帮助做页面的跳转，此方法的作用就是做页面的跳转。
 37      *
 38      * @param page
 39      * @return
 40      */
 41     @RequestMapping(value = "/{page}")
 42     public String showPage(@PathVariable String page) {
 43         System.out.println("============================================" + page);
 44         return page;
 45     }
 46 
 47     /**
 48      * 添加用户信息
 49      *
 50      * @param users
 51      * @return
 52      */
 53     @RequestMapping(value = "addUser")
 54     public String addUser(Users users) {
 55         this.usersService.addUser(users);
 56         return "redirect:/users/findUserAll";
 57     }
 58 
 59     /**
 60      * 查询全部用户
 61      *
 62      * @param model
 63      * @return
 64      */
 65     @RequestMapping(value = "findUserAll")
 66     public String findUserAll(Model model) {
 67         List<Users> list = this.usersService.findUserAll();
 68         model.addAttribute("list", list);
 69         return "showUsers";
 70     }
 71 
 72     /**
 73      * 根据用户id查询用户信息
 74      *
 75      * @param id
 76      * @param model
 77      * @return
 78      */
 79     @RequestMapping(value = "findUserById")
 80     public String findUserById(Integer id, Model model) {
 81         Users user = this.usersService.findUserById(id);
 82         model.addAttribute("user", user);
 83         return "updateUser";
 84     }
 85 
 86     /**
 87      * 更新用户信息
 88      *
 89      * @param users
 90      * @return
 91      */
 92     @RequestMapping(value = "editUser")
 93     public String editUser(Users users) {
 94         this.usersService.updateUser(users);
 95         return "redirect:/users/findUserAll";
 96     }
 97 
 98     @RequestMapping(value = "delUser")
 99     public String delUser(Integer id) {
100         this.usersService.deleteUserById(id);
101         return "redirect:/users/findUserAll";
102 
103     }
104 }

创建几个页面，如下所示：

 1 <!DOCTYPE html>
 2 <html xmlns:th="http://www.w3.org/1999/xhtml">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>展示用户数据</title>
 6 
 7     <!-- 最新版本的 Bootstrap 核心 CSS 文件 -->
 8     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css">
 9     <!-- 最新的 Bootstrap 核心 JavaScript 文件 -->
10     <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.min.js"></script>
11     <style>
12         tr th {
13             text-align: center;
14         }
15 
16         tr td {
17             text-align: center;
18         }
19 
20         h1 {
21             text-align: center;
22         }
23     </style>
24 </head>
25 <body>
26 
27 <h1>用户列表</h1>
28 <br/>
29 <hr/>
30 <br/><br/>
31 
32 <div class="row">
33     <div class="col-md-2"></div>
34     <div class="col-md-8">
35         <div style="text-align: left;padding-left:900px;">
36             <a th:href="@{/users/input}" class="btn btn-success">新增用户</a>
37         </div>
38         <br/>
39         <table class="table table-striped table-hover table-condensed">
40             <tr>
41                 <th>用户ID</th>
42                 <th>用户姓名</th>
43                 <th>用户年龄</th>
44                 <th>操作</th>
45             </tr>
46             <tr th:each="user : ${list}">
47                 <td th:text="${user.id}"></td>
48                 <td th:text="${user.name}"></td>
49                 <td th:text="${user.age}"></td>
50                 <td>
51                     <a th:href="@{/users/findUserById(id=${user.id})}" class="btn btn-warning">更新用户</a>
52                     <a th:href="@{/users/delUser(id=${user.id})}" class="btn btn-danger">删除用户</a>
53                 </td>
54             </tr>
55         </table>
56     </div>
57     <div class="col-md-2"></div>
58 </div>
59 </body>
60 </html>

 1 <!DOCTYPE html>
 2 <html xmlns:th="http://www.w3.org/1999/xhtml">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>添加用户</title>
 6 </head>
 7 <body>
 8 <h1 style="text-align: center">用户管理~新增用户</h1>
 9 <hr/>
10 
11 <div style="text-align: center">
12     <form th:action="@{/users/addUser}" method="post">
13         用户姓名：<input type="text" name="name"/><br/>
14         用户年龄：<input type="text" name="age"/><br/><br/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
15         <input type="submit" value="确定"/> &nbsp;&nbsp;&nbsp;
16         <input type="reset" value="重置"/><br/>
17     </form>
18 </div>
19 
20 </body>
21 </html>

 1 <!DOCTYPE html>
 2 <html xmlns:th="http://www.w3.org/1999/xhtml">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Insert title here</title>
 6 </head>
 7 <body>
 8 
 9 <h1 style="text-align: center">用户管理~修改用户</h1>
10 <hr/>
11 
12 <div style="text-align: center">
13     <form th:action="@{/users/editUser}" method="post">    
14         <input type="hidden" name="id" th:field="${user.id}"/>   <!-- th:field做数据的回显 -->
15         用户姓名：<input type="text" name="name" th:field="${user.name}"/><br/>
16         用户年龄：<input type="text" name="age" th:field="${user.age}"/><br/>
17         <input type="submit" value="确定"/><br/>
18     </form>
19 </div>
20 </body>
21 </html>

创建启动类，如下所示：

 1 package com.bie.springboothello;
 2 
 3 import org.mybatis.spring.annotation.MapperScan;
 4 import org.springframework.boot.SpringApplication;
 5 import org.springframework.boot.autoconfigure.SpringBootApplication;
 6 
 7 @SpringBootApplication
 8 // @MapperScan注解，用户扫描MyBatis的Mapper接口，根据扫描的接口生成代理对象
 9 @MapperScan(value = "com.bie.springboothello.mapper")
10 public class SpringbootHelloApplication {
11 
12     public static void main(String[] args) {
13         SpringApplication.run(SpringbootHelloApplication.class, args);
14     }
15 
16 
17 }

运行效果，如下所示：

新增用户的界面。

修改用户的界面。

 

 

---

错误描述一，出现这种问题是由于serverTimezone的问题，在application.properties后面配置一下即可。如下所示：

1 spring.datasource.url=jdbc:mysql://localhost:3306/biehl?useUnicode=true&characterEncoding=utf8&serverTimezone=UTC

出现的错误，如下所示：

 1 java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a more specifc time zone value if you want to utilize time zone support.
 2     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 3     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 4     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 5     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 6     at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 7     at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 8     at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.19.jar:8.0.19]
 9     at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.19.jar:8.0.19]
10     at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.19.jar:8.0.19]
11     at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197) ~[mysql-connector-java-8.0.19.jar:8.0.19]
12     at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1558) ~[druid-1.1.10.jar:1.1.10]
13     at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1623) ~[druid-1.1.10.jar:1.1.10]
14     at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2468) ~[druid-1.1.10.jar:1.1.10]
15 Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a more specifc time zone value if you want to utilize time zone support.
16     at sun.reflect.GeneratedConstructorAccessor30.newInstance(Unknown Source) ~[na:na]
17     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_191]
18     at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_191]
19     at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.19.jar:8.0.19]
20     at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:85) ~[mysql-connector-java-8.0.19.jar:8.0.19]
21     at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:132) ~[mysql-connector-java-8.0.19.jar:8.0.19]
22     at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2118) ~[mysql-connector-java-8.0.19.jar:8.0.19]
23     at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2142) ~[mysql-connector-java-8.0.19.jar:8.0.19]
24     at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1310) ~[mysql-connector-java-8.0.19.jar:8.0.19]
25     at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:967) ~[mysql-connector-java-8.0.19.jar:8.0.19]
26     at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826) ~[mysql-connector-java-8.0.19.jar:8.0.19]
27     ... 6 common frames omitted

错误描述二，出现这个问题是很多啊，百度也有很多的讲解，自己也记录一下吧。由于使用的idea工具，springboot开发，由于UsersMapper.xml所在的位置不同，我的映射文件所在位置，项目结构，如下所示。

在mybatis中dao接口与mapper配置文件在做映射绑定的时候出现问题，简单说，就是接口与xml要么是找不到，要么是找到了却匹配不到。错误如下所示：

 1 org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.bie.springboothello.mapper.UsersMapper.insertUser
 2     at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:235) ~[mybatis-3.5.3.jar:3.5.3]
 3     at org.apache.ibatis.binding.MapperMethod.<init>(MapperMethod.java:53) ~[mybatis-3.5.3.jar:3.5.3]
 4     at org.apache.ibatis.binding.MapperProxy.lambda$cachedMapperMethod$0(MapperProxy.java:98) ~[mybatis-3.5.3.jar:3.5.3]
 5     at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660) ~[na:1.8.0_191]
 6     at org.apache.ibatis.binding.MapperProxy.cachedMapperMethod(MapperProxy.java:97) ~[mybatis-3.5.3.jar:3.5.3]
 7     at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:92) ~[mybatis-3.5.3.jar:3.5.3]
 8     at com.sun.proxy.$Proxy63.insertUser(Unknown Source) ~[na:na]
 9     at com.bie.springboothello.service.impl.UsersServiceImpl.addUser(UsersServiceImpl.java:21) ~[classes/:na]
10     at com.bie.springboothello.service.impl.UsersServiceImpl$$FastClassBySpringCGLIB$$6c792bea.invoke(<generated>) ~[classes/:na]
11     at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE]
12     at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:771) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
13     at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
14     at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
15     at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:366) ~[spring-tx-5.2.5.RELEASE.jar:5.2.5.RELEASE]
16     at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.5.RELEASE.jar:5.2.5.RELEASE]
17     at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
18     at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
19     at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691) ~[spring-aop-5.2.5.RELEASE.jar:5.2.5.RELEASE]
20     at com.bie.springboothello.service.impl.UsersServiceImpl$$EnhancerBySpringCGLIB$$9682ec5a.addUser(<generated>) ~[classes/:na]
21     at com.bie.springboothello.controller.UsersController.addUser(UsersController.java:55) ~[classes/:na]
22     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
23     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
24     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
25     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
26     at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
27     at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
28     at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
29     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
30     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
31     at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
32     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
33     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
34     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
35     at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
36     at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
37     at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
38     at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
39     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
40     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
41     at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.33.jar:9.0.33]
42     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
43     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
44     at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
45     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
46     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
47     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
48     at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
49     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
50     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
51     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
52     at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
53     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
54     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
55     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
56     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
57     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.33.jar:9.0.33]
58     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.33.jar:9.0.33]
59     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.33.jar:9.0.33]
60     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.33.jar:9.0.33]
61     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.33.jar:9.0.33]
62     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.33.jar:9.0.33]
63     at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) [tomcat-embed-core-9.0.33.jar:9.0.33]
64     at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.33.jar:9.0.33]
65     at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.33.jar:9.0.33]
66     at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1594) [tomcat-embed-core-9.0.33.jar:9.0.33]
67     at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.33.jar:9.0.33]
68     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
69     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
70     at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.33.jar:9.0.33]
71     at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]

注意：Mapper接口开发需要遵循以下规范：

　　1）、Mapper.xml文件中的namespace与mapper接口的类路径相同。
　　2）、Mapper接口方法名和Mapper.xml中定义的每个statement的id相同。
　　3）、Mapper接口方法的输入参数类型和mapper.xml中定义的每个sql 的parameterType的类型相同。
　　4）、Mapper接口方法的输出参数类型和mapper.xml中定义的每个sql的resultType的类型相同。

除了可以在pom.xml配置resource，把*Mapper.xml文件放到resource文件夹下管理，也可以解决这个问题的。

需要新增，下面配置。

1 # 后台打印sql语句
2 mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
3 
4 # 指定sql映射文件位置,mapper下的所有.xml文件都是映射文件
5 mybatis.mapper-locations=classpath:mapper/*Mapper.xml

项目结构如下所示：