Spring boot Mybatis整合构建Rest服务（超细版）

 Springboot+ Mybatis+MySql整合构建Rest服务（涵盖增、删、改、查）

1.概要

1.1 为什么要使用Spring  boot?

　　1.1.1 简单方便、配置少、整合了大多数框架

　　 1.1.2 适用于微服务搭建，搭建的微服务与Spring clound进行完美融合，都属于Spring家族，Spring boot+Spring clound属于品牌机，dubbo+zookeeper属于组装机，品牌机稳定性更好

1.2 使用Spring boot+Mybatis构建Restful项目详细步骤

2. 准备

2.1 使用的工具及详细版本

2.1.1 JDK       Version:1.8.0_181

2.1.2 Idea      Version:Ultimate Edition 2018.1.6

2.1.3 MySql    Version:MySql 5.7

2.1.4 Maven   Version:3.5.4

2.1.5 Mybatis-Generator   Version:1.3.5

2.1.6 Http Test Restful Webservice Idea带，没看到版本号

2.2 maven仓库地址：https://mvnrepository.com/

3. POM文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.wuji</groupId>
    <artifactId>spring_boot_mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.1.RELEASE</version>
    </parent>

    <dependencies>

        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.1.1.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-test -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>2.1.1.RELEASE</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.alibaba/druid-spring-boot-starter -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.5</version>
                <configuration>
                    <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
            </plugin>

        </plugins>
    </build>
</project>

4. 详细开发步骤

4.1 spring_boot_mybatis模块创建：File->New->Module如下图

4.2 弹出窗口，选择左侧maven，点击右侧“下一步”，如下图：

4.3 输入，红线指的地方都设为None,点击“下一步”如下图：

4.4 输入，点击“完成”如下图：

4.5 模块创建完成，如下图：

4.5.1 src\main\java存放源文件

4.5.2 src\main\resources存放资源文件

4.5.3 Src\test\java存放测试文件

4.6 创建层次结构，父包为：com.wuji

4.6.1 创建mapper层：选中左侧src\main下“java”，点击File->New->Package，弹出窗口输入：com.wuji.mapper，点击“OK”

4.6.2 创建service层：同上

4.6.3 创建entity层：同上

4.6.4 创建controller层：同上

4.6.5 创建springboot启动：同上

4.6.6 最终结构图如下：

4.7 在pom文件中添加依赖包

4.7.1 打开https://mvnrepository.com网址，搜索：spring-boot，从列表中点击：spring-boot-starter-web，选择 2.1.1.RELEASE版本，

如下图：

4.7.2 同上点击：spring-boot-starter-test，选择2.1.1.RELEASE版本

4.7.3 添加mybatis-spring-boot-starter依赖，选择1.3.2版本

4.7.4 添加mysql-connector-java依赖，选择5.1.38版本

4.7.5 添加druid-spring-boot-starter依赖，选择版本1.1.10版本

4.8 配置Mybatis-Generator生成器

4.8.1 Pom文件中添加Mybatis-Generator插件依赖

4.8.2 Idea中配置：Run->Edit Configurations,具体设置如下图：

4.8.3 设置generatorConfig.xml文件，具体如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>
   <classPathEntry location="D:\MyBatisGenerator\mysql-connector-java-5.1.38.jar"/>

    <context id="MysqlContext" targetRuntime="MyBatis3" defaultModelType="flat">

        <commentGenerator>
            <property name="suppressAllComments" value="true"/>
            <property name="suppressDate" value="true" />
        </commentGenerator>

        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/daducha"
                        userId="root"
                        password="root">
        </jdbcConnection>

        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!--生成PO实体类-->
        <javaModelGenerator targetPackage="com.wuji.entity.po"  targetProject="src/main/java">
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!--生成Mybatis XML Mapper Sql操作-->
        <sqlMapGenerator targetPackage="mapping" targetProject="src/main/resources">
        </sqlMapGenerator>

        <!--生成Mybatis Mpper数据操作接口-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.wuji.mapper"  targetProject="src/main/java">
        </javaClientGenerator>

        <table tableName="users" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false"  selectByExampleQueryId="false"/>
       <!--
        <table tableName="%">
            <generatedKey column="id" sqlStatement="Mysql"/>
        </table>
        -->
    </context>
</generatorConfiguration>

4.8.9 将generatorConfig.xml文件放置到resources/generator/generatorConfig.xml下面

4.8.10 以上配置完成即可运行，如下图：

4.8.11 生成的po、mapper、mapping文件如下：

PO文件：

package com.wuji.entity.po;

public class User {
    private Integer id;

    private String name;

    private Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

Mapper文件：

package com.wuji.mapper;

import com.wuji.entity.po.User;

public interface UserMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);
}

Mapping文件（按照规则放在了资源文件夹下面）：

 <?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.wuji.mapper.UserMapper">
   <resultMap id="BaseResultMap" type="com.wuji.entity.po.User">
     <id column="id" jdbcType="INTEGER" property="id" />
     <result column="name" jdbcType="VARCHAR" property="name" />
     <result column="age" jdbcType="INTEGER" property="age" />
   </resultMap>
   <sql id="Base_Column_List">
     id, name, age
   </sql>
   <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
     select
     <include refid="Base_Column_List" />
     from users
     where id = #{id,jdbcType=INTEGER}
   </select>
   <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
     delete from users
     where id = #{id,jdbcType=INTEGER}
   </delete>
   <insert id="insert" parameterType="com.wuji.entity.po.User">
     insert into users (id, name, age
       )
     values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER}
       )
   </insert>
   <insert id="insertSelective" parameterType="com.wuji.entity.po.User">
     insert into users
     <trim prefix="(" suffix=")" suffixOverrides=",">
       <if test="id != null">
         id,
       </if>
       <if test="name != null">
         name,
       </if>
       <if test="age != null">
         age,
       </if>
     </trim>
     <trim prefix="values (" suffix=")" suffixOverrides=",">
       <if test="id != null">
         #{id,jdbcType=INTEGER},
       </if>
       <if test="name != null">
         #{name,jdbcType=VARCHAR},
       </if>
       <if test="age != null">
         #{age,jdbcType=INTEGER},
       </if>
     </trim>
   </insert>
   <update id="updateByPrimaryKeySelective" parameterType="com.wuji.entity.po.User">
     update users
     <set>
       <if test="name != null">
         name = #{name,jdbcType=VARCHAR},
       </if>
       <if test="age != null">
         age = #{age,jdbcType=INTEGER},
       </if>
     </set>
     where id = #{id,jdbcType=INTEGER}
   </update>
   <update id="updateByPrimaryKey" parameterType="com.wuji.entity.po.User">
     update users
     set name = #{name,jdbcType=VARCHAR},
       age = #{age,jdbcType=INTEGER}
     where id = #{id,jdbcType=INTEGER}
   </update>
 </mapper>

4.9 application.yml文件配置（格式很严格，注意节点的缩近和对齐，有问题直接加微信回复更快）

 server:
   port: 8080
 spring:
   datasource:
            name: daducha
            type: com.alibaba.druid.pool.DruidDataSource
            druid:
                 url: jdbc:mysql://127.0.0.1:3306/daducha
                 username: root
                 password: root
                 maxActive: 20
                 initialSize: 1
                 maxWait: 60000
                 minIdle: 1
                 timeBetweenEvictionRunsMillis: 60000
                 minEvictableIdleTimeMillis: 300000
                 testWhileIdle: true
                 testOnBorrow: false
                 testOnReturn: false
                 poolPreparedStatements: true
                 maxOpenPreparedStatements: 20
                 driver-class-name: com.mysql.jdbc.Driver

 mybatis:
   mapper-locations: classpath:mapping/*.xml
   type-aliases-package: com.wuji.entity.po

5.10 service接口文件

 package com.wuji.service;

 import com.wuji.entity.po.User;

 public interface UserService {
     int addUser(User user);
     int delUserById(int id);
     int updateUserById(int id,String userName);
     User getUserById(int id);
 }

5.11 service接口实现类

 package com.wuji.service;

 import com.wuji.entity.po.User;
 import com.wuji.mapper.UserMapper;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;

 @Service
 public class UserServiceImpl implements UserService {

     @Autowired
     private UserMapper userMapper;

     public int addUser(User user) {
         return userMapper.insert(user);
     }

     public int delUserById(int id) {
         return userMapper.deleteByPrimaryKey(id);
     }

     public int updateUserById(int id,String userName) {
         User user=getUserById(id);
         user.setName(userName);
         return userMapper.updateByPrimaryKey(user);
     }

     public User getUserById(int id) {
         return userMapper.selectByPrimaryKey(id);
     }
 }

5.12 controller restful风格实现

 package com.wuji.controller;
 /**
  * author:zhangwuji
  * date:2018-12-31
  * weixin:17091005779
  */
 import com.wuji.entity.po.User;
 import com.wuji.service.UserService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RestController;

 import java.util.List;

 @RestController
 @RequestMapping("/api/user")
 public class UserController {

     @Autowired
     private UserService userService;

     @RequestMapping(value = "/add",method = RequestMethod.POST)
     public int addUser(User user){
         return userService.addUser(user);
     }

     @RequestMapping(value = "/get",method = RequestMethod.GET)
     public User getUser(int id){
         return userService.getUserById(id);
     }

     @RequestMapping(value = "/del",method = RequestMethod.DELETE )
     public int delUser(int id){return userService.delUserById(id);}

     @RequestMapping(value = "/update",method = RequestMethod.POST)
     public int updateUser(User user){return userService.updateUserById(user);}

 }

5.13.spring boot 启动器文件

 package com.wuji.springboot;
 /**
  * author:zhangwuji
  * date:2018-12-31
  * weixin:17091005779
  */

 import org.mybatis.spring.annotation.MapperScan;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.ComponentScans;

 @SpringBootApplication
 @ComponentScan(basePackages = {"com.wuji"})
 @MapperScan("com.wuji.mapper")
 public class Application {
     public static void main(String[] args) {
         SpringApplication.run(Application.class,args);
     }
 }

5.14 使用Test Restful Web Service进行接口测试如下：

5.15 测试结果如下图

5.16 最最终项目结构图(此结构自认为是很标准的，大家可以多发表意见)

5. 错误抛析及解决方法（可能会遇到的坑）

5.1 创建包一定要先选择src\main\java目录，右击New->Package，弹出窗口输入全路径如：com.wuji.mapper，否则会在当前选择路径下创建包，不符合Java命名约定

5.2 在启动类上添加@SpringBootApplication注解时，不能引入包；原因是：没有下载依赖

5.3 配置mybatis-generator时，working directory要设置成模块路径如：E:\JavaProjects\pring_boot_mybatis

5.4 运行mybatis-generator时出现如下错误：[ERROR] Failed to execute goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli) on project spring_boot_mybatis: configfile E:\JavaProjects\pring_boot_mybatis\src\main\resources\generator\generatorConfig.xml does not exist ，经检查是由于generatorConfig.xml 直接在\src\main\resources下，故报找不到错误。放入正确的目录。再一次提醒Java同胞，不要任性，要遵守java命名规则约束。这些规则的使用可以标准化项目，比自己定义的结构要清晰。

5.5 [ERROR] Failed to execute goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli) on project spring_boot_mybatis: XML Parser Error on line 46: 元素类型为 "context" 的内容必须匹配 "(property*,plugin*,commentGenerator?,(connectionFactory|jdbcConnection),javaTypeResolver?,javaModelGenerator,sqlMapGenerator?,javaClientGenerator?,table+)"。 -> [Help 1] 节点要严格按照"(property*,plugin*,commentGenerator?,(connectionFactory|jdbcConnection),javaTypeResolver?,javaModelGenerator,sqlMapGenerator?,javaClientGenerator?,table+)"顺序

5.6 [ERROR] Failed to execute goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli) on project spring_boot_mybatis: Execution default-cli of goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate failed: Cannot resolve classpath entry: mysql-connector-java-5.1.38.jar -> [Help 1]是由于这个节点：<classPathEntry location="mysql-connector-java-5.1.38.jar"/>location要指定绝对路径如：<classPathEntry location="D:\MyBatisGenerator\mysql-connector-java-5.1.38.jar"/>

5.7 java.lang.IllegalStateException: Failed to load property source from location 'classpath:/application.yml'原因：application.yml首字母大写了，改为小写

5.8  org.yaml.snakeyaml.parser.ParserException: while parsing a block mapping  原因：yml文件节点没有对齐，将Mybatis节点与Spring节点对齐

5.9 No active profile set, falling back to default profiles: default这个错误是由于idea没有设置默认启动环境。具体设置如下：

5.10 Caused by: java.lang.ClassNotFoundException: org.springframework.boot.bind.RelaxedPropertyResolver这个错误是由于没有添加：<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.1.RELEASE</version>
</parent>从而找不到RelaxedPropertyResolver这个类

5.11 Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.还是出现在yml文件节点。具体是druid:这个节点，要有层次结构。详见yml文件。

5.12 server:
   port: 8080  错误：server:标黄，提示无法解析。由于port:和8080间要加空格。

5.13 Springboot 启动文件报错，原因是@ComponentScan写成了@ComponentScans

5.14 No MyBatis mapper was found in '[com.wuji.springboot]' package. Please check your configuration.这个原因是启动器上要添加：@MapperScan("com.wuji.mapper")注解

5.15 Field userService in com.wuji.controller.UserController required a bean of type 'com.wuji.service.UserService' that could not be found.原因：说明IOC里没有创建Bean，在启动文件上手动添加：@ComponentScan(basePackages = {"com.wuji"})注解

5.16

6.总结：

此文章非常详细介绍了Springboot2.0与Mybatis的整合，并且采用Rest风格作为输入和输出，项目还使用了两个很优秀的工具，一个是：Mybatis-Generator代码生成器，可以方便生成PO、Mapper接口、MapperXml映射文件，而且直接配置生成到项目指定目录下，不用做任何修改，生成的文件即可使用，同时无忌也介绍了怎样嵌入到Idea详细见上面。另一个是：Test Restful Web Service，这是个用于Rest风格接口测试工具，直接集成到Idea了，可以非常方便使用进行测试。

7.张无忌介绍：

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