Springboot集成mybatis通用Mapper与分页插件PageHelper

插件介绍

通用 Mapper 是一个能够实现任意 MyBatis 通用方法的框架，项目提供了常规的增删改查操做以及 Example 相关的单表操做。通用 Mapper 是为了解决 MyBatis 使用中 90% 的基本操做，PageHelper则提供通用的分页查询功能，使用它们能够很方便的进行开发，能够节省开发人员大量的时间。

通用Mapper的GIT地址： https://gitee.com/free/Mapper

分页插件的GIT地址： https://github.com/pagehelper/Mybatis-PageHelper

项目结构

 

导入依赖

 1 <!-- 通用Mapper插件  2  文档地址：https://gitee.com/free/Mapper/wikis/Home -->
 3 <dependency>
 4     <groupId>tk.mybatis</groupId>
 5     <artifactId>mapper-spring-boot-starter</artifactId>
 6     <version>2.1.5</version>
 7 </dependency>
 8 <!-- 分页插件  9  文档地址：https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md -->
10 <dependency>
11     <groupId>com.github.pagehelper</groupId>
12     <artifactId>pagehelper-spring-boot-starter</artifactId>
13     <version>1.2.10</version>
14 </dependency>
15 <!-- MYSQL包 -->
16 <dependency>
17     <groupId>mysql</groupId>
18     <artifactId>mysql-connector-java</artifactId>
19 </dependency>
20 <!-- 默认就内嵌了Tomcat 容器，如须要更换容器也极其简单-->
21 <dependency>
22     <groupId>org.springframework.boot</groupId>
23     <artifactId>spring-boot-starter-web</artifactId>
24 </dependency>

属性配置

在 application.properties 文件中分别添加上数据库、Mybatis、通用Mapper、PageHelper的属性配置

spring.datasource.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&useSSL=false
spring.datasource.username=root
spring.datasource.password=123456
# 若是想看到mybatis日志须要作以下配置
logging.level.com.carry=DEBUG
######### Mybatis 自身配置 ##########
mybatis.mapper-locations=classpath:com/carry/mapper/*Mapper.xml
mybatis.type-aliases-package=com.carry.entity
# 驼峰命名规范 如：数据库字段是  order_id 那么 实体字段就要写成 orderId
mybatis.configuration.map-underscore-to-camel-case=true
######### 通用Mapper ##########
# 主键自增回写方法,默认值MYSQL,详细说明请看文档
mapper.identity=MYSQL
mapper.mappers=tk.mybatis.mapper.common.Mapper
# 设置 insert 和 update 中，是否判断字符串类型!=''
mapper.not-empty=true
# 枚举按简单类型处理
mapper.enum-as-simple-type=true
######### 分页插件 ##########
pagehelper.helper-dialect=mysql
pagehelper.params=count=countSql
pagehelper.reasonable=false
pagehelper.support-methods-arguments=true

通用Mapper：

• mapper.enum-as-simple-type： 枚举按简单类型处理，若是有枚举字段则须要加上该配置才会作映射
• mapper.not-empty： 设置之后，会去判断 insert 和 update 中符串类型!=''

分页插件：

• pagehelper.reasonable： 分页合理化参数，默认值为false。当该参数设置为 true 时，pageNum<=0 时会查询第一页， pageNum>pages（超过总数时），会查询最后一页。默认false 时，直接根据参数进行查询
• support-methods-arguments： 支持经过 Mapper 接口参数来传递分页参数，默认值false，分页插件会从查询方法的参数值中，自动根据上面 params 配置的字段中取值，查找到合适的值时就会自动分页

注意事项：

因为 mybatis.mapper-locations=classpath:com/carry/mapper/*.xml配置的在java package中，而Spring Boot默认只打入java package -> *.java，因此咱们须要给pom.xml文件添加以下内容

 1 <build>
 2     <resources>
 3         <resource>
 4             <directory>src/main/resources</directory>
 5         </resource>
 6         <resource>
 7             <directory>src/main/java</directory>
 8             <includes>
 9                 <include>**/*.xml</include>
10             </includes>
11             <filtering>true</filtering>
12         </resource>
13     </resources>
14     <plugins>
15         <plugin>
16             <groupId>org.springframework.boot</groupId>
17             <artifactId>spring-boot-maven-plugin</artifactId>
18         </plugin>
19     </plugins>
20 </build>

具体编码

一、表结构

建立一张 user表

CREATE TABLE `user` (
  `id` int(8) NOT NULL AUTO_INCREMENT COMMENT '主键自增',
  `username` varchar(50) NOT NULL COMMENT '用户名',
  `password` varchar(50) NOT NULL COMMENT '密码',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='用户表';

二、实体类

 1 package com.carry.entity;  2 
 3 import java.io.Serializable;  4 
 5 import javax.persistence.GeneratedValue;  6 import javax.persistence.GenerationType;  7 import javax.persistence.Id;  8 import javax.persistence.Table;  9 
10 @Table(name = "user") 11 public class User implements Serializable { 12 
13     private static final long serialVersionUID = -8057591359892731452L; 14 
15  @Id 16     @GeneratedValue(strategy = GenerationType.IDENTITY) 17     private Long id; 18     private String username; 19     private String password; 20     public Long getId() { 21         return id; 22  } 23     public void setId(Long id) { 24         this.id = id; 25  } 26     public String getUsername() { 27         return username; 28  } 29     public void setUsername(String username) { 30         this.username = username; 31  } 32     public String getPassword() { 33         return password; 34  } 35     public void setPassword(String password) { 36         this.password = password; 37  } 38     
39     
40     public User() {} 41     public User(String username, String password) { 42         super(); 43         this.username = username; 44         this.password = password; 45  } 46 }

三、持久层

package com.carry.mapper; import com.carry.entity.User; import tk.mybatis.mapper.common.Mapper; 

public interface UserMapper extends Mapper<User> { 

　　/** 
 * 根据用户名统计（假设它是一个很复杂的SQL） 
 * @param username 用户名 
 * @return 统计结果 
 */ 
　　int countByUsername(String username); 
}

四、映射文件UserMapper.xml

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.carry.mapper.UserMapper">
4 
5   <select id="countByUsername" resultType="java.lang.Integer">
6  SELECT count(1) FROM user WHERE username = #{username} 7   </select>
8 </mapper>

五、启动类

import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import tk.mybatis.spring.annotation.MapperScan; @SpringBootApplication @MapperScan(basePackages = "com.carry.mapper") public class SpringbootMapperPagehelperApplication { 　　public static void main(String[] args) { 　　　　        
　　　　SpringApplication.run(SpringbootMapperPagehelperApplication.class, args); 　　} }

 

测试

完成数据访问层接口后，编写一个junit测试类来检验代码的正确性。

 1 package com.carry;  2 
 3 import org.junit.Test;  4 import org.junit.runner.RunWith;  5 import org.slf4j.Logger;  6 import org.slf4j.LoggerFactory;  7 import org.springframework.beans.factory.annotation.Autowired;  8 import org.springframework.boot.test.context.SpringBootTest;  9 import org.springframework.test.context.junit4.SpringRunner; 10 
11 import com.carry.entity.User; 12 import com.carry.mapper.UserMapper; 13 import com.github.pagehelper.PageHelper; 14 import com.github.pagehelper.PageInfo; 15 
16 @RunWith(SpringRunner.class) 17 @SpringBootTest 18 public class SpringbootMapperPagehelperApplicationTests { 19 
20     private final Logger logger = LoggerFactory.getLogger(this.getClass()); 21 
22  @Autowired 23     private UserMapper userMapper; 24 
25  @Test 26     public void test() { 27         try { 28             final User user1 = new User("u1", "p1"); 29             final User user2 = new User("u1", "p2"); 30             final User user3 = new User("u3", "p3"); 31  userMapper.insertSelective(user1); 32             logger.info("[user1回写主键] - [{}]", user1.getId()); 33  userMapper.insertSelective(user2); 34             logger.info("[user2回写主键] - [{}]", user2.getId()); 35  userMapper.insertSelective(user3); 36             logger.info("[user3回写主键] - [{}]", user3.getId()); 37             final int count = userMapper.countByUsername("u1"); 38             logger.info("[调用本身写的SQL] - [{}]", count); 39 
40             // TODO 模拟分页
41             for (int i = 0; i < 20; i++) { 42                 userMapper.insertSelective(new User("u" + i, "p" + i)); 43  } 44             // TODO 分页 + 排序 this.userMapper.selectAll() 这一句就是咱们须要写的查询，有了这两款插件无缝切换各类数据库
45             final PageInfo<User> pageInfo = PageHelper.startPage(1, 10).setOrderBy("id desc") 46                     .doSelectPageInfo(() -> this.userMapper.selectAll()); 47             logger.info("[lambda写法] - [分页信息] - [{}]", pageInfo.toString()); 48 
49             PageHelper.startPage(1, 10).setOrderBy("id desc"); 50             final PageInfo<User> userPageInfo = new PageInfo<>(this.userMapper.selectAll()); 51             logger.info("[普通写法] - [{}]", userPageInfo); 52         } catch (Exception e) { 53  logger.error(e.getMessage()); 54  } 55  } 56 
57 }