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

<!-- 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>

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

<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>

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;
    }
}

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); }

<?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>

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); 
　　} 
}

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());
        }
    }

}