Spring boot Mybatis整合構建Rest服務（超細版）

 Springboot+ Mybatis+MySql整合構建Rest服務（涵蓋增、刪、改、查）

1.概要

1.1 為什麼要使用Spring  boot?

 　　1.1.1 簡單方便、配置少、整合了大多數框架

　　 1.1.2 適用於微服務搭建，搭建的微服務與Spring clound進行完美融合，都屬於Spring家族，Spring boot+Spring clound屬於品牌機，dubbo+zookeeper屬於組裝機，品牌機穩定性更好

1.2 使用Spring boot+Mybatis構建Restful項目詳細步驟

2. 準備

2.1 使用的工具及詳細版本

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帶，沒看到版本號

2.2 maven倉庫地址：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. 詳細開發步驟

4.1 spring_boot_mybatis模塊創建：File->New->Module如下圖

4.2 彈出視窗，選擇左側maven，點擊右側“下一步”，如下圖：

4.3 輸入，紅線指的地方都設為None,點擊“下一步”如下圖：

4.4 輸入，點擊“完成”如下圖：

4.5 模塊創建完成，如下圖：

4.5.1 src\main\java存放源文件

4.5.2 src\main\resources存放資源文件

4.5.3 Src\test\java存放測試文件

4.6 創建層次結構，父包為：com.wuji

4.6.1 創建mapper層：選中左側src\main下“java”，點擊File->New->Package，彈出視窗輸入：com.wuji.mapper，點擊“OK”

4.6.2 創建service層：同上

4.6.3 創建entity層：同上

4.6.4 創建controller層：同上

4.6.5 創建springboot啟動：同上

4.6.6 最終結構圖如下：

4.7 在pom文件中添加依賴包

4.7.1 打開https://mvnrepository.com網址，搜索：spring-boot，從列表中點擊：spring-boot-starter-web，選擇 2.1.1.RELEASE版本，

如下圖：

4.7.2 同上點擊：spring-boot-starter-test，選擇2.1.1.RELEASE版本

4.7.3 添加mybatis-spring-boot-starter依賴，選擇1.3.2版本

4.7.4 添加mysql-connector-java依賴，選擇5.1.38版本

4.7.5 添加druid-spring-boot-starter依賴，選擇版本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插件依賴

4.8.2 Idea中配置：Run->Edit Configurations,具體設置如下圖：

4.8.3 設置generatorConfig.xml文件，具體如下：

<?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實體類-->
        <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數據操作介面-->
        <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 將generatorConfig.xml文件放置到resources/generator/generatorConfig.xml下麵

4.8.10 以上配置完成即可運行，如下圖：

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（按照規則放在了資源文件夾下麵）：

 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（格式很嚴格，註意節點的縮近和對齊，有問題直接加微信回覆更快）

 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介面文件

 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介面實現類

 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風格實現

 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 啟動器文件

 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進行介面測試如下：

 5.15 測試結果如下圖

5.16 最最終項目結構圖(此結構自認為是很標準的，大家可以多發表意見)

5. 錯誤拋析及解決方法（可能會遇到的坑）

5.1 創建包一定要先選擇src\main\java目錄，右擊New->Package，彈出視窗輸入全路徑如：com.wuji.mapper，否則會在當前選擇路徑下創建包，不符合Java命名約定

5.2 在啟動類上添加@SpringBootApplication註解時，不能引入包；原因是：沒有下載依賴

5.3 配置mybatis-generator時，working directory要設置成模塊路徑如：E:\JavaProjects\pring_boot_mybatis

5.4 運行mybatis-generator時出現如下錯誤：[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 ，經檢查是由於generatorConfig.xml 直接在\src\main\resources下，故報找不到錯誤。放入正確的目錄。再一次提醒Java同胞，不要任性，要遵守java命名規則約束。這些規則的使用可以標準化項目，比自己定義的結構要清晰。

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: 元素類型為 "context" 的內容必須匹配 "(property*,plugin*,commentGenerator?,(connectionFactory|jdbcConnection),javaTypeResolver?,javaModelGenerator,sqlMapGenerator?,javaClientGenerator?,table+)"。 -> [Help 1] 節點要嚴格按照"(property*,plugin*,commentGenerator?,(connectionFactory|jdbcConnection),javaTypeResolver?,javaModelGenerator,sqlMapGenerator?,javaClientGenerator?,table+)"順序

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]是由於這個節點：<classPathEntry location="mysql-connector-java-5.1.38.jar"/>location要指定絕對路徑如：<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首字母大寫了，改為小寫

5.8  org.yaml.snakeyaml.parser.ParserException: while parsing a block mapping  原因：yml文件節點沒有對齊，將Mybatis節點與Spring節點對齊

5.9 No active profile set, falling back to default profiles: default這個錯誤是由於idea沒有設置預設啟動環境。具體設置如下：

5.10 Caused by: java.lang.ClassNotFoundException: org.springframework.boot.bind.RelaxedPropertyResolver這個錯誤是由於沒有添加：<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.1.RELEASE</version>
</parent>從而找不到RelaxedPropertyResolver這個類

5.11 Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.還是出現在yml文件節點。具體是druid:這個節點，要有層次結構。詳見yml文件。

5.12 server:
   port: 8080  錯誤：server:標黃，提示無法解析。由於port:和8080間要加空格。

5.13 Springboot 啟動文件報錯，原因是@ComponentScan寫成了@ComponentScans

5.14 No MyBatis mapper was found in '[com.wuji.springboot]' package. Please check your configuration.這個原因是啟動器上要添加：@MapperScan("com.wuji.mapper")註解

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：說明IOC里沒有創建Bean，在啟動文件上手動添加：@ComponentScan(basePackages = {"com.wuji"})註解

5.16 

6.總結：

此文章非常詳細介紹了Springboot2.0與Mybatis的整合，並且採用Rest風格作為輸入和輸出，項目還使用了兩個很優秀的工具，一個是：Mybatis-Generator代碼生成器，可以方便生成PO、Mapper介面、MapperXml映射文件，而且直接配置生成到項目指定目錄下，不用做任何修改，生成的文件即可使用，同時無忌也介紹了怎樣嵌入到Idea詳細見上面。另一個是：Test Restful Web Service，這是個用於Rest風格介面測試工具，直接集成到Idea了，可以非常方便使用進行測試。

7.張無忌介紹：

張無忌專註Java技術10餘年，產品控、代碼控，擁有豐富的項目經驗，主持研發了多個成功上線的大型互聯網項目

熱愛互聯網，精通Java、J2EE，深入研究過JDK、Spring、Mybatis源碼，擅長互聯網高併發、高可靠架構設計。願意

和他人分享自己對技術的理解和感悟。需要更多資源或有任何疑問可以添加張無忌微信（17091005779）