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）：
1 <?xml version="1.0" encoding="utf-8"?>
2 <!doctype mapper public "-//mybatis.org//dtd mapper 3.0//en" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
3 <mapper namespace="com.wuji.mapper.usermapper">
4 <resultmap id="baseresultmap" type="com.wuji.entity.po.user">
5 <id column="id" jdbctype="integer" property="id" />
6 <result column="name" jdbctype="varchar" property="name" />
7 <result column="age" jdbctype="integer" property="age" />
8 </resultmap>
9 <sql id="base_column_list">
10 id, name, age
11 </sql>
12 <select id="selectbyprimarykey" parametertype="java.lang.integer" resultmap="baseresultmap">
13 select
14 <include refid="base_column_list" />
15 from users
16 where id = #{id,jdbctype=integer}
17 </select>
18 <delete id="deletebyprimarykey" parametertype="java.lang.integer">
19 delete from users
20 where id = #{id,jdbctype=integer}
21 </delete>
22 <insert id="insert" parametertype="com.wuji.entity.po.user">
23 insert into users (id, name, age
24 )
25 values (#{id,jdbctype=integer}, #{name,jdbctype=varchar}, #{age,jdbctype=integer}
26 )
27 </insert>
28 <insert id="insertselective" parametertype="com.wuji.entity.po.user">
29 insert into users
30 <trim prefix="(" suffix=")" suffixoverrides=",">
31 <if test="id != null">
32 id,
33 </if>
34 <if test="name != null">
35 name,
36 </if>
37 <if test="age != null">
38 age,
39 </if>
40 </trim>
41 <trim prefix="values (" suffix=")" suffixoverrides=",">
42 <if test="id != null">
43 #{id,jdbctype=integer},
44 </if>
45 <if test="name != null">
46 #{name,jdbctype=varchar},
47 </if>
48 <if test="age != null">
49 #{age,jdbctype=integer},
50 </if>
51 </trim>
52 </insert>
53 <update id="updatebyprimarykeyselective" parametertype="com.wuji.entity.po.user">
54 update users
55 <set>
56 <if test="name != null">
57 name = #{name,jdbctype=varchar},
58 </if>
59 <if test="age != null">
60 age = #{age,jdbctype=integer},
61 </if>
62 </set>
63 where id = #{id,jdbctype=integer}
64 </update>
65 <update id="updatebyprimarykey" parametertype="com.wuji.entity.po.user">
66 update users
67 set name = #{name,jdbctype=varchar},
68 age = #{age,jdbctype=integer}
69 where id = #{id,jdbctype=integer}
70 </update>
71 </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）
1 server: 2 port: 8080 3 spring: 4 datasource: 5 name: daducha 6 type: com.alibaba.druid.pool.druiddatasource 7 druid: 8 url: jdbc:mysql://127.0.0.1:3306/daducha 9 username: root 10 password: root 11 maxactive: 20 12 initialsize: 1 13 maxwait: 60000 14 minidle: 1 15 timebetweenevictionrunsmillis: 60000 16 minevictableidletimemillis: 300000 17 testwhileidle: true 18 testonborrow: false 19 testonreturn: false 20 poolpreparedstatements: true 21 maxopenpreparedstatements: 20 22 driver-class-name: com.mysql.jdbc.driver 23 24 mybatis: 25 mapper-locations: classpath:mapping/*.xml 26 type-aliases-package: com.wuji.entity.po
5.10 service接口文件
1 package com.wuji.service;
2
3 import com.wuji.entity.po.user;
4
5 public interface userservice {
6 int adduser(user user);
7 int deluserbyid(int id);
8 int updateuserbyid(int id,string username);
9 user getuserbyid(int id);
10 }
5.11 service接口实现类
1 package com.wuji.service;
2
3 import com.wuji.entity.po.user;
4 import com.wuji.mapper.usermapper;
5 import org.springframework.beans.factory.annotation.autowired;
6 import org.springframework.stereotype.service;
7
8 @service
9 public class userserviceimpl implements userservice {
10
11 @autowired
12 private usermapper usermapper;
13
14 public int adduser(user user) {
15 return usermapper.insert(user);
16 }
17
18 public int deluserbyid(int id) {
19 return usermapper.deletebyprimarykey(id);
20 }
21
22 public int updateuserbyid(int id,string username) {
23 user user=getuserbyid(id);
24 user.setname(username);
25 return usermapper.updatebyprimarykey(user);
26 }
27
28 public user getuserbyid(int id) {
29 return usermapper.selectbyprimarykey(id);
30 }
31 }
5.12 controller restful风格实现
1 package com.wuji.controller;
2 /**
3 * author:zhangwuji
4 * date:2018-12-31
5 * weixin:17091005779
6 */
7 import com.wuji.entity.po.user;
8 import com.wuji.service.userservice;
9 import org.springframework.beans.factory.annotation.autowired;
10 import org.springframework.web.bind.annotation.requestmapping;
11 import org.springframework.web.bind.annotation.requestmethod;
12 import org.springframework.web.bind.annotation.restcontroller;
13
14 import java.util.list;
15
16 @restcontroller
17 @requestmapping("/api/user")
18 public class usercontroller {
19
20 @autowired
21 private userservice userservice;
22
23 @requestmapping(value = "/add",method = requestmethod.post)
24 public int adduser(user user){
25 return userservice.adduser(user);
26 }
27
28 @requestmapping(value = "/get",method = requestmethod.get)
29 public user getuser(int id){
30 return userservice.getuserbyid(id);
31 }
32
33 @requestmapping(value = "/del",method = requestmethod.delete )
34 public int deluser(int id){return userservice.deluserbyid(id);}
35
36 @requestmapping(value = "/update",method = requestmethod.post)
37 public int updateuser(user user){return userservice.updateuserbyid(user);}
38
39
40 }
5.13.spring boot 启动器文件
1 package com.wuji.springboot;
2 /**
3 * author:zhangwuji
4 * date:2018-12-31
5 * weixin:17091005779
6 */
7
8 import org.mybatis.spring.annotation.mapperscan;
9 import org.springframework.boot.springapplication;
10 import org.springframework.boot.autoconfigure.springbootapplication;
11 import org.springframework.context.annotation.componentscan;
12 import org.springframework.context.annotation.componentscans;
13
14 @springbootapplication
15 @componentscan(basepackages = {"com.wuji"})
16 @mapperscan("com.wuji.mapper")
17 public class application {
18 public static void main(string[] args) {
19 springapplication.run(application.class,args);
20 }
21 }
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，同时无忌老师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：
张无忌专注java技术10余年，产品控、代码控，拥有丰富的项目经验，主持研发了多个成功上线的大型互联网项目
热爱互联网，精通java、j2ee，深入研究过jdk、spring、mybatis源码，擅长互联网高并发、高可靠架构设计。愿意
和他人分享自己对技术的理解和感悟。需要更多资源或有任何疑问可以添加张无忌微信（17091005779）
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