Springboot集成mybatis通用Mapper与分页插件PageHelper(推荐)

插件介绍

通用 Mapper 是一个可以实现任意 MyBatis 通用方法的框架,项目提供了常规的增删改查操作以及 Example 相关的单表操作。通用 Mapper 是为了解决 MyBatis 使用中 90% 的基本操作,PageHelper则提供通用的分页查询功能,使用它们可以很方便的进行开发,可以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

Springboot集成mybatis通用Mapper与分页插件PageHelper(推荐)

导入依赖

<!-- 通用Mapper插件
 文档地址:https://gitee.com/free/Mapper/wikis/Home -->
<dependency>
    <groupId>tk.mybatis</groupId>
    <artifactId>mapper-spring-boot-starter</artifactId>
    <version>2.1.5</version>
</dependency>
<!-- 分页插件
 文档地址:https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md -->
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.10</version>
</dependency>
<!-- MYSQL包 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- 默认就内嵌了Tomcat 容器,如需要更换容器也极其简单-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</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
# 如果想看到mybatis日志需要做如下配置
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,如果有枚举字段则需要加上该配置才会做映射
  • mapper.not-empty: 设置以后,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: 支持通过 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:

由于 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,所以我们需要给pom.xml文件添加如下内容

<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
        </resource>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

具体编码

1、表结构

创建一张 user

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

2、实体类

package com.carry.entity;

import java.io.Serializable;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Table(name = "user")
public class User implements Serializable {

    private static final long serialVersionUID = -8057591359892731452L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String password;
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
    
    public User() {}
    public User(String username, String password) {
        super();
        this.username = username;
        this.password = password;
    }
}

3、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); }

4、映射文件UserMapper.xml

<?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.carry.mapper.UserMapper">

  <select id="countByUsername" resultType="java.lang.Integer">
      SELECT count(1) FROM user WHERE username = #{username}
  </select>
</mapper>

5、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。

package com.carry;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import com.carry.entity.User;
import com.carry.mapper.UserMapper;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbootMapperPagehelperApplicationTests {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    @Autowired
    private UserMapper userMapper;

    @Test
    public void test() {
        try {
            final User user1 = new User("u1", "p1");
            final User user2 = new User("u1", "p2");
            final User user3 = new User("u3", "p3");
            userMapper.insertSelective(user1);
            logger.info("[user1回写主键] - [{}]", user1.getId());
            userMapper.insertSelective(user2);
            logger.info("[user2回写主键] - [{}]", user2.getId());
            userMapper.insertSelective(user3);
            logger.info("[user3回写主键] - [{}]", user3.getId());
            final int count = userMapper.countByUsername("u1");
            logger.info("[调用自己写的SQL] - [{}]", count);

            // TODO 模拟分页
            for (int i = 0; i < 20; i++) {
                userMapper.insertSelective(new User("u" + i, "p" + i));
            }
            // TODO 分页 + 排序 this.userMapper.selectAll() 这一句就是我们需要写的查询,有了这两款插件无缝切换各种数据库
            final PageInfo<User> pageInfo = PageHelper.startPage(1, 10).setOrderBy("id desc")
                    .doSelectPageInfo(() -> this.userMapper.selectAll());
            logger.info("[lambda写法] - [分页信息] - [{}]", pageInfo.toString());

            PageHelper.startPage(1, 10).setOrderBy("id desc");
            final PageInfo<User> userPageInfo = new PageInfo<>(this.userMapper.selectAll());
            logger.info("[普通写法] - [{}]", userPageInfo);
        } catch (Exception e) {
            logger.error(e.getMessage());
        }
    }

}

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