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Mybatis 学习之 分页实现

article 2024/10/4 5:15:38

文章目录

  • 1. Mybatis
    • 1.1. 代码实现
  • 2. Mybatis Plus
    • 2.1. 代码实现
    • 2.2. 特别注意
  • 3. PageHelper
    • 3.1. 代码实现
    • 3.2. 特别注意
  • 参考资料

1. Mybatis

1.1. 代码实现

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan(value = "com.example.demo.mapper")
@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

}

package com.example.demo.mapper;

import com.example.demo.model.SysUser;
import com.example.demo.model.page.BasePageReq;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

@Mapper
public interface UserMapper {

    List<SysUser> page(@Param(value = "pageReq") BasePageReq pageReq);

}

<?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.example.demo.mapper.UserMapper">

    <select id="page" resultType="com.example.demo.model.SysUser">
        <bind name="startIndex" value="(pageReq.pageNum-1)*pageReq.pageSize"/>
        SELECT 
        	ID AS id, 
        	NAME AS name, 
        	AGE AS age
        FROM SYS_USER
        ORDER BY ID ASC
        LIMIT #{startIndex}, #{pageReq.pageSize}
    </select>

</mapper>

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.example.demo.model

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
	<groupId>org.mybatis.spring.boot</groupId>
	<artifactId>mybatis-spring-boot-starter</artifactId>
	<version>2.3.0</version>
</dependency>

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<version>8.0.15</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
	<groupId>org.projectlombok</groupId>
	<artifactId>lombok</artifactId>
	<version>1.18.24</version>
	<scope>provided</scope>
</dependency>
<dependency>
	<groupId>com.google.guava</groupId>
	<artifactId>guava</artifactId>
	<version>30.1-jre</version>
</dependency>

2. Mybatis Plus

2.1. 代码实现

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan(value = "com.example.demo.mapper")
@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

}

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

Page<SysUser> list = userMapper.page(new Page<>(pageReq.getPageNum(), pageReq.getPageSize()));

package com.example.demo.mapper;

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.demo.model.SysUser;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

@Mapper
public interface UserMapper {

    Page<SysUser> page(@Param(value = "pageReq") IPage<SysUser> pageReq);

}

<?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.example.demo.mapper.UserMapper">

    <select id="page" resultType="com.example.demo.model.SysUser">
        SELECT ID AS id, NAME AS name, AGE AS age
        FROM SYS_USER
        ORDER BY ID ASC
    </select>

</mapper>

mybatis-plus:
  mapper-locations: classpath*:mapper/*.xml
  type-aliases-package: com.example.demo.model
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
	<groupId>com.baomidou</groupId>
	<artifactId>mybatis-plus-boot-starter</artifactId>
	<version>3.5.1</version>
</dependency>
<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<version>8.0.15</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
	<groupId>org.projectlombok</groupId>
	<artifactId>lombok</artifactId>
	<version>1.18.24</version>
	<scope>provided</scope>
</dependency>
<dependency>
	<groupId>com.google.guava</groupId>
	<artifactId>guava</artifactId>
	<version>30.1-jre</version>
</dependency>

2.2. 特别注意

  • Mybatis Plus 分页功能中使用了 CCJSqlParser，其中 CCJSqlParser#Statement 在处理 复杂 SQL 时，存在 性能问题

3. PageHelper

3.1. 代码实现

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan(value = "com.example.demo.mapper")
@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

}

import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;

Page<SysUser> list = PageHelper.startPage(pageReq.getPageNum(), pageReq.getPageSize()).doSelectPage(() -> userMapper.page());

package com.example.demo.mapper;

import com.example.demo.model.SysUser;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

@Mapper
public interface UserMapper {

    List<SysUser> page();

}

<?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.example.demo.mapper.UserMapper">

    <select id="page" resultType="com.example.demo.model.SysUser">
        SELECT ID AS id, NAME AS name, AGE AS age
        FROM SYS_USER
        ORDER BY ID ASC
    </select>

</mapper>

mybatis-plus:
  mapper-locations: classpath*:mapper/*.xml
  type-aliases-package: com.example.demo.model
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
	<groupId>com.baomidou</groupId>
	<artifactId>mybatis-plus-boot-starter</artifactId>
	<version>3.5.1</version>
</dependency>
<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<version>8.0.15</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper -->
<dependency>
	<groupId>com.github.pagehelper</groupId>
	<artifactId>pagehelper</artifactId>
	<version>5.0.0</version>
</dependency>
<dependency>
	<groupId>com.github.jsqlparser</groupId>
	<artifactId>jsqlparser</artifactId>
	<version>4.3</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
	<groupId>org.projectlombok</groupId>
	<artifactId>lombok</artifactId>
	<version>1.18.24</version>
	<scope>provided</scope>
</dependency>
<dependency>
	<groupId>com.google.guava</groupId>
	<artifactId>guava</artifactId>
	<version>30.1-jre</version>
</dependency>

3.2. 特别注意

  • PageHelper 分页功能中使用了 CCJSqlParser，其中 CCJSqlParser#Statement 在处理 复杂 SQL 时，存在 性能问题

参考资料

  • Mybatis PageHelper编译SQL引发的一次性能问题.18286262

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