28.整合mybatis

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1.使用注解方式

项目工程结构:

(1) MyDirectory.java

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package com.example.demo.entity;

public class MyDirectory {
    private Integer directoryId;

    private String directoryName;

    private String remark;

    private Integer userId;

    public MyDirectory() {
		super();
	}

	public MyDirectory(Integer directoryId, String directoryName, String remark, Integer userId) {
		super();
		this.directoryId = directoryId;
		this.directoryName = directoryName;
		this.remark = remark;
		this.userId = userId;
	}

	public Integer getDirectoryId() {
        return directoryId;
    }

    public void setDirectoryId(Integer directoryId) {
        this.directoryId = directoryId;
    }

    public String getDirectoryName() {
        return directoryName;
    }

    public void setDirectoryName(String directoryName) {
        this.directoryName = directoryName == null ? null : directoryName.trim();
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark == null ? null : remark.trim();
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

	@Override
	public String toString() {
		return "MyDirectory [directoryId=" + directoryId + ", directoryName=" + directoryName + ", remark=" + remark
				+ ", userId=" + userId + "]";
	}
    
}

(2) MyDirectoryMapper.java

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package com.example.demo.dao;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
//import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.example.demo.entity.MyDirectory;

/*
 * 想要让SpringBoot识别到这个Mapper接口类
 * 方法一: 在mapper.java上添加@Mapper注解
 * 方法二: 在启动类上添加@MapperScan(basePackages = {"com.example.demo.dao"})
 */
//@Mapper
public interface MyDirectoryMapper {
	
	@Delete("delete from t_directory where directory_id = #{directoryId}")
    int deleteByPrimaryKey(Integer directoryId);

	@Insert("insert into t_directory(directory_name, remark, user_id) values(#{directoryName}, #{remark}, #{userId})")
    int insert(MyDirectory record);

	@Select("select directory_id as directoryId, directory_name as directoryName, remark, user_id as userId from t_directory where directory_id = #{directoryId}")
    MyDirectory selectByPrimaryKey(Integer directoryId);

	@Update("update t_directory set directory_name = #{directoryName}, remark = #{remark}, user_id = #{userId} where directory_id = #{directoryId}")
    int updateByPrimaryKey(MyDirectory record);
    
    @Select("select * from t_directory")
    public List<MyDirectory> getAllDirectory();
    
}

(3) 启动类: 

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package com.example.demo;

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

/*
 * 想要让SpringBoot识别到这个Mapper接口类
 * 方法一: 在mapper.java上添加@Mapper注解
 * 方法二: 在启动类上添加@MapperScan(basePackages = {"com.example.demo.dao"})
 */
@SpringBootApplication
@MapperScan(basePackages = {"com.example.demo.dao"})
public class Application {

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

}

(4) mybatis.cfg.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
  
<configuration>
	<settings>
		<!-- 让log4j去记录sql日志，打印mybatis执行的sql语句 -->
		<setting name="logImpl" value="LOG4J"/>
	</settings>

</configuration>

(5) application.yml

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# 数据源配置信息
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://localhost:3306/demo_filesystem
      username: root
      password: 123456
      initial-size: 3
      min-idle: 2
      max-active: 10
      max-wait: 15000
      
      stat-view-servlet:
        login-username: admin
        login-password: 123456
        # allow和deny可以为空
        allow: 192.168.10.25,127.0.0.1,192.168.30.23,192.168.5.26
        deny: 
        url-pattern: /druid/*
        # 默认为false，不开启        
        enabled: true
        
# mybatis
mybatis:
  config-location: classpath:mybatis.cfg.xml

(6) log4j.properties

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# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# MyBatis logging configuration...
log4j.logger.org.mybatis.example.BlogMapper=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

(7) 测试类: 

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package com.example.demo;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.example.demo.dao.MyDirectoryMapper;
import com.example.demo.entity.MyDirectory;

@SpringBootTest
class ApplicationTests {

	@Autowired
	private MyDirectoryMapper myDirectoryMapper;
	
	@Test
	void contextLoads() {
		MyDirectory myDirectory = myDirectoryMapper.selectByPrimaryKey(1);
		System.out.println(myDirectory);
		// MyDirectory [directoryId=1, directoryName=home, remark=home目录, userId=1]
	}

}

(8) pom.xml

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<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.7.0</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>15_springboot_mybatis-1</artifactId>
	<version>1.0</version>
	<name>15_springboot_mybatis-1</name>
	<description>Spring Boot mybatis-1</description>
	<properties>
		<java.version>1.8</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		
		<!-- druid-spring-boot-starter -->
		<dependency>
		    <groupId>com.alibaba</groupId>
		    <artifactId>druid-spring-boot-starter</artifactId>
		    <version>1.2.9</version>
		</dependency>
		
		<!-- mybatis-spring-boot-starter -->
		<dependency>
		    <groupId>org.mybatis.spring.boot</groupId>
		    <artifactId>mybatis-spring-boot-starter</artifactId>
		    <version>2.2.2</version>
		</dependency>
		
		<!-- spring-boot-starter-log4j -->
		<dependency>
		    <groupId>org.springframework.boot</groupId>
		    <artifactId>spring-boot-starter-log4j</artifactId>
		    <version>1.3.8.RELEASE</version>
		</dependency>
		
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

2.使用Mapper.xml

(1) MyDirectoryMapper.java

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package com.example.demo.dao;

import java.util.List;

//import org.apache.ibatis.annotations.Mapper;

import com.example.demo.entity.MyDirectory;

//@Mapper
public interface MyDirectoryMapper {
	
    int deleteByPrimaryKey(Integer directoryId);

    int insert(MyDirectory record);

    MyDirectory selectByPrimaryKey(Integer directoryId);

    int updateByPrimaryKey(MyDirectory record);
    
    public List<MyDirectory> getAllDirectory();
    
}

(2) MyDirectoryMapper.xml

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<?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.dao.MyDirectoryMapper" >
  <resultMap id="BaseResultMap" type="com.example.demo.entity.MyDirectory" >
    <id column="directory_id" property="directoryId" jdbcType="INTEGER" />
    <result column="directory_name" property="directoryName" jdbcType="VARCHAR" />
    <result column="remark" property="remark" jdbcType="VARCHAR" />
    <result column="user_id" property="userId" jdbcType="INTEGER" />
  </resultMap>
  <sql id="Base_Column_List" >
    directory_id, directory_name, remark, user_id
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from t_directory
    where directory_id = #{directoryId,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from t_directory
    where directory_id = #{directoryId,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.example.demo.entity.MyDirectory" >
    insert into t_directory (directory_id, directory_name, remark, 
      user_id)
    values (#{directoryId,jdbcType=INTEGER}, #{directoryName,jdbcType=VARCHAR}, #{remark,jdbcType=VARCHAR}, 
      #{userId,jdbcType=INTEGER})
  </insert>
  <insert id="insertSelective" parameterType="com.example.demo.entity.MyDirectory" >
    insert into t_directory
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="directoryId != null" >
        directory_id,
      </if>
      <if test="directoryName != null" >
        directory_name,
      </if>
      <if test="remark != null" >
        remark,
      </if>
      <if test="userId != null" >
        user_id,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="directoryId != null" >
        #{directoryId,jdbcType=INTEGER},
      </if>
      <if test="directoryName != null" >
        #{directoryName,jdbcType=VARCHAR},
      </if>
      <if test="remark != null" >
        #{remark,jdbcType=VARCHAR},
      </if>
      <if test="userId != null" >
        #{userId,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.example.demo.entity.MyDirectory" >
    update t_directory
    <set >
      <if test="directoryName != null" >
        directory_name = #{directoryName,jdbcType=VARCHAR},
      </if>
      <if test="remark != null" >
        remark = #{remark,jdbcType=VARCHAR},
      </if>
      <if test="userId != null" >
        user_id = #{userId,jdbcType=INTEGER},
      </if>
    </set>
    where directory_id = #{directoryId,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.example.demo.entity.MyDirectory" >
    update t_directory
    set directory_name = #{directoryName,jdbcType=VARCHAR},
      remark = #{remark,jdbcType=VARCHAR},
      user_id = #{userId,jdbcType=INTEGER}
    where directory_id = #{directoryId,jdbcType=INTEGER}
  </update>
  
  <!-- 查询所有文件夹 -->
  <select id="getAllDirectory" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from t_directory
  </select>
  
</mapper>

(3) application.yml

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# 数据源配置信息
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://localhost:3306/demo_filesystem
      username: root
      password: 123456
      initial-size: 3
      min-idle: 2
      max-active: 10
      max-wait: 15000
      
      stat-view-servlet:
        login-username: admin
        login-password: 123456
        # allow和deny可以为空
        allow: 192.168.10.25,127.0.0.1,192.168.30.23,192.168.5.26
        deny: 
        url-pattern: /druid/*
        # 默认为false，不开启        
        enabled: true
        
# mybatis
mybatis:
  config-location: classpath:mybatis.cfg.xml
  # 添加mapper.xml
  # 方法一：在application.yml中设置mybatis.mapper-locations
  # 方法二：在mybatis.cfg.xml中配置<mappers>
  mapper-locations:
  - classpath:mapper/*Mapper.xml

(4) mybatis.cfg.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
  
<configuration>
	<settings>
		<!-- 让log4j去记录sql日志，打印mybatis执行的sql语句 -->
		<setting name="logImpl" value="LOG4J"/>
	</settings>
	
	<!-- 
		添加mapper.xml
		方法一：在application.yml中设置mybatis.mapper-locations
		方法二：在mybatis.cfg.xml中配置<mappers>
	 -->
	<!-- 
	<mappers>
		<mapper resource="mapper/MyDirectoryMapper.xml"/>
	</mappers>
	 -->
</configuration>

(5) 测试类

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package com.example.demo;

import java.util.Iterator;
import java.util.List;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.example.demo.dao.MyDirectoryMapper;
import com.example.demo.entity.MyDirectory;

@SpringBootTest
class ApplicationTests {

	@Autowired
	private MyDirectoryMapper myDirectoryMapper;
	
	@Test
	public void testQueryAllDirectory() {
		List<MyDirectory> directoryList = myDirectoryMapper.getAllDirectory();
		for (MyDirectory myDirectory : directoryList) {
			System.out.println(myDirectory);
			/*
			2022-06-18 09:12:25.375  INFO 14184 --- [           main] c.a.d.s.b.a.DruidDataSourceAutoConfigure : Init DruidDataSource
			2022-06-18 09:12:26.311  INFO 14184 --- [           main] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} inited
			DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
			2022-06-18 09:12:26.744  INFO 14184 --- [           main] com.example.demo.ApplicationTests        : Started ApplicationTests in 2.136 seconds (JVM running for 2.916)
			DEBUG [main] - Creating a new SqlSession
			DEBUG [main] - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@5f2de715] was not registered for synchronization because synchronization is not active
			DEBUG [main] - JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@2f3166a] will not be managed by Spring
			DEBUG [main] - ==>  Preparing: select directory_id, directory_name, remark, user_id from t_directory
			DEBUG [main] - ==> Parameters: 
			DEBUG [main] - <==      Total: 16
			DEBUG [main] - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@5f2de715]
			MyDirectory [directoryId=1, directoryName=home, remark=home目录, userId=1]
			MyDirectory [directoryId=2, directoryName=usr, remark=usr目录, userId=1]
			MyDirectory [directoryId=3, directoryName=source, remark=source目录, userId=1]
			MyDirectory [directoryId=4, directoryName=tmp, remark=tmp目录, userId=2]
			MyDirectory [directoryId=5, directoryName=bin, remark=bin目录, userId=1]
			MyDirectory [directoryId=6, directoryName=boot, remark=boot目录, userId=2]
			MyDirectory [directoryId=7, directoryName=dev, remark=dev目录, userId=1]
			MyDirectory [directoryId=8, directoryName=etc, remark=etc目录, userId=1]
			MyDirectory [directoryId=9, directoryName=var, remark=var目录, userId=1]
			MyDirectory [directoryId=10, directoryName=test1, remark=test11, userId=1]
			MyDirectory [directoryId=11, directoryName=test2, remark=test22, userId=1]
			MyDirectory [directoryId=15, directoryName=css, remark=css file, userId=1]
			MyDirectory [directoryId=16, directoryName=js, remark=js file, userId=1]
			MyDirectory [directoryId=17, directoryName=jar, remark=jar包目录1, userId=1]
			MyDirectory [directoryId=18, directoryName=doc, remark=word文档，doc和docx, userId=1]
			MyDirectory [directoryId=19, directoryName=xls, remark=xls表格，xls和xlsx, userId=1]
			2022-06-18 09:12:27.063  INFO 14184 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closing ...
			2022-06-18 09:12:27.066  INFO 14184 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closed
			 */
		}
	}

}

3.不使用mybatis.cfg.xml

直接去除mybatis.cfg.xml，项目也可以正常运行，得到查询结果，但是没有sql语句的打印输出，以下配置为添加sql语句打印输出

(1) 删除mybatis.cfg.xml

(2) 修改application.yml

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# spring.datasource ...
# mybatis
mybatis:
  # 删除config-location: classpath:mybatis.cfg.xml
  mapper-locations:
  - classpath:mapper/*Mapper.xml
  # 配置输出日志
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

(3) 测试类

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package com.example.demo;

import java.util.List;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.example.demo.dao.MyDirectoryMapper;
import com.example.demo.entity.MyDirectory;

@SpringBootTest
class ApplicationTests {

	@Autowired
	private MyDirectoryMapper myDirectoryMapper;
	
	@Test
	public void testQueryDirectoryById() {
		MyDirectory myDirectory = myDirectoryMapper.selectByPrimaryKey(2);
		System.out.println(myDirectory);
		// 2022-06-18 11:53:48.895  INFO 2408 --- [           main] com.example.demo.ApplicationTests        : Starting ApplicationTests using Java 1.8.0_271 on DESKTOP-IOB28AF with PID 2408 (started by Tom in E:\SpringToolSuite\project\demo-4.8.1\16_springboot_mybatis-2)
		// 2022-06-18 11:53:48.896  INFO 2408 --- [           main] com.example.demo.ApplicationTests        : No active profile set, falling back to 1 default profile: "default"
		// 2022-06-18 11:53:49.412  INFO 2408 --- [           main] c.a.d.s.b.a.DruidDataSourceAutoConfigure : Init DruidDataSource
		// 2022-06-18 11:53:50.351  INFO 2408 --- [           main] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} inited
		// Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
		// Parsed mapper file: 'file [E:\SpringToolSuite\project\demo-4.8.1\16_springboot_mybatis-2\target\classes\mapper\MyDirectoryMapper.xml]'
		// 2022-06-18 11:53:50.775  INFO 2408 --- [           main] com.example.demo.ApplicationTests        : Started ApplicationTests in 2.125 seconds (JVM running for 2.911)
		// Creating a new SqlSession
		// SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1bb15351] was not registered for synchronization because synchronization is not active
		// JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@642413d4] will not be managed by Spring
		// ==>  Preparing: select directory_id, directory_name, remark, user_id from t_directory where directory_id = ?
		// ==> Parameters: 2(Integer)
		// <==    Columns: directory_id, directory_name, remark, user_id
		// <==        Row: 2, usr, usr目录, 1
		// <==      Total: 1
		// Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1bb15351]
		// MyDirectory [directoryId=2, directoryName=usr, remark=usr目录, userId=1]
		// 2022-06-18 11:53:51.065  INFO 2408 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closing ...
		// 2022-06-18 11:53:51.069  INFO 2408 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closed

	}

}

4.使用PageHelper(引入依赖包)

(1) pom.xml，引入pageHelper的依赖包

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<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	
	<dependencies>

		<!-- pagehelper -->
		<dependency>
		    <groupId>com.github.pagehelper</groupId>
		    <artifactId>pagehelper</artifactId>
		    <version>5.3.1</version>
		</dependency>
		
	</dependencies>

</project>

(2) 创建PageHelperAutoConfiguration类，向Spring容器中注入PageInterceptor对象

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package com.example.demo.config;

import org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInterceptor;

@Configuration
@ConditionalOnClass(value = {PageHelper.class, MybatisAutoConfiguration.class})
public class PageHelperAutoConfiguration {

	@Bean
	public PageInterceptor pageInterceptor() {
		return new PageInterceptor();
	}
	
}

(3) 测试类

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package com.example.demo;

import java.util.List;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.example.demo.dao.MyDirectoryMapper;
import com.example.demo.entity.MyDirectory;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;

@SpringBootTest
class ApplicationTests {

	@Autowired
	private MyDirectoryMapper myDirectoryMapper;
	
	@Test
	public void testPageHelper1() {
		Page<MyDirectory> page = PageHelper.startPage(1, 5);
		List<MyDirectory> directoryList = myDirectoryMapper.getAllDirectory();
		System.out.println(page.getTotal());
		for (MyDirectory myDirectory : directoryList) {
			System.out.println(myDirectory);
		}
		
		// 2022-06-18 13:38:44.414  INFO 6540 --- [           main] com.example.demo.ApplicationTests        : Starting ApplicationTests using Java 1.8.0_271 on DESKTOP-IOB28AF with PID 6540 (started by Tom in E:\SpringToolSuite\project\demo-4.8.1\16_springboot_mybatis-2)
		// 2022-06-18 13:38:44.415  INFO 6540 --- [           main] com.example.demo.ApplicationTests        : No active profile set, falling back to 1 default profile: "default"
		// 2022-06-18 13:38:44.955  INFO 6540 --- [           main] c.a.d.s.b.a.DruidDataSourceAutoConfigure : Init DruidDataSource
		// 2022-06-18 13:38:45.911  INFO 6540 --- [           main] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} inited
		// Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
		// Registered plugin: 'com.github.pagehelper.PageInterceptor@27e5b378'
		// Parsed mapper file: 'file [E:\SpringToolSuite\project\demo-4.8.1\16_springboot_mybatis-2\target\classes\mapper\MyDirectoryMapper.xml]'
		// 2022-06-18 13:38:46.309  INFO 6540 --- [           main] com.example.demo.ApplicationTests        : Started ApplicationTests in 2.138 seconds (JVM running for 2.919)
		// Creating a new SqlSession
		// SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@54067fdc] was not registered for synchronization because synchronization is not active
		// Cache Hit Ratio [SQL_CACHE]: 0.0
		// JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@141d3d43] will not be managed by Spring
		// ==>  Preparing: SELECT count(0) FROM t_directory
		// ==> Parameters: 
		// <==    Columns: count(0)
		// <==        Row: 16
		// <==      Total: 1
		// ==>  Preparing: select directory_id, directory_name, remark, user_id from t_directory LIMIT ?
		// ==> Parameters: 5(Integer)
		// <==    Columns: directory_id, directory_name, remark, user_id
		// <==        Row: 1, home, home目录, 1
		// <==        Row: 2, usr, usr目录, 1
		// <==        Row: 3, source, source目录, 1
		// <==        Row: 4, tmp, tmp目录, 2
		// <==        Row: 5, bin, bin目录, 1
		// <==      Total: 5
		// Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@54067fdc]
		// total = 16
		// MyDirectory [directoryId=1, directoryName=home, remark=home目录, userId=1]
		// MyDirectory [directoryId=2, directoryName=usr, remark=usr目录, userId=1]
		// MyDirectory [directoryId=3, directoryName=source, remark=source目录, userId=1]
		// MyDirectory [directoryId=4, directoryName=tmp, remark=tmp目录, userId=2]
		// MyDirectory [directoryId=5, directoryName=bin, remark=bin目录, userId=1]
		// 2022-06-18 13:38:46.698  INFO 6540 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closing ...
		// 2022-06-18 13:38:46.702  INFO 6540 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closed

	}

}

5.使用PageHelper(使用starter)

(1) pom.xml引入PageHelper starter

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<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	
	<dependencies>
		
		<!-- pagehelper-spring-boot-starter -->
		<dependency>
		    <groupId>com.github.pagehelper</groupId>
		    <artifactId>pagehelper-spring-boot-starter</artifactId>
		    <version>1.4.2</version>
		</dependency>
		
	</dependencies>

</project>

(2) 测试类

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package com.example.demo;

import java.util.List;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.example.demo.dao.MyDirectoryMapper;
import com.example.demo.entity.MyDirectory;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;

@SpringBootTest
class ApplicationTests {

	@Autowired
	private MyDirectoryMapper myDirectoryMapper;
	
	@Test
	public void testPageHelper1() {
		Page<MyDirectory> page = PageHelper.startPage(1, 5);
		List<MyDirectory> directoryList = myDirectoryMapper.getAllDirectory();
		System.out.println("total = " + page.getTotal());
		for (MyDirectory myDirectory : directoryList) {
			System.out.println(myDirectory);
		}
		
		// 2022-06-18 13:48:08.229  INFO 1224 --- [           main] com.example.demo.ApplicationTests        : Starting ApplicationTests using Java 1.8.0_271 on DESKTOP-IOB28AF with PID 1224 (started by Tom in E:\SpringToolSuite\project\demo-4.8.1\17_springboot_mybatis-3)
		// 2022-06-18 13:48:08.230  INFO 1224 --- [           main] com.example.demo.ApplicationTests        : No active profile set, falling back to 1 default profile: "default"
		// 2022-06-18 13:48:08.780  INFO 1224 --- [           main] c.a.d.s.b.a.DruidDataSourceAutoConfigure : Init DruidDataSource
		// 2022-06-18 13:48:09.765  INFO 1224 --- [           main] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} inited
		// Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
		// Parsed mapper file: 'file [E:\SpringToolSuite\project\demo-4.8.1\17_springboot_mybatis-3\target\classes\mapper\MyDirectoryMapper.xml]'


		// ,------.                           ,--.  ,--.         ,--.                         
		// |  .--. '  ,--,--.  ,---.   ,---.  |  '--'  |  ,---.  |  |  ,---.   ,---.  ,--.--. 
		// |  '--' | ' ,-.  | | .-. | | .-. : |  .--.  | | .-. : |  | | .-. | | .-. : |  .--' 
		// |  | --'  \ '-'  | ' '-' ' \   --. |  |  |  | \   --. |  | | '-' ' \   --. |  |    
		// `--'       `--`--' .`-  /   `----' `--'  `--'  `----' `--' |  |-'   `----' `--'    
		//                    `---'                                   `--'                        is intercepting.

		// 2022-06-18 13:48:10.206  INFO 1224 --- [           main] com.example.demo.ApplicationTests        : Started ApplicationTests in 2.223 seconds (JVM running for 3.019)
		// Creating a new SqlSession
		// SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@54d1608f] was not registered for synchronization because synchronization is not active
		// Cache Hit Ratio [SQL_CACHE]: 0.0
		// JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@2ae62bb6] will not be managed by Spring
		// ==>  Preparing: SELECT count(0) FROM t_directory
		// ==> Parameters: 
		// <==    Columns: count(0)
		// <==        Row: 16
		// <==      Total: 1
		// ==>  Preparing: select directory_id, directory_name, remark, user_id from t_directory LIMIT ?
		// ==> Parameters: 5(Integer)
		// <==    Columns: directory_id, directory_name, remark, user_id
		// <==        Row: 1, home, home目录, 1
		// <==        Row: 2, usr, usr目录, 1
		// <==        Row: 3, source, source目录, 1
		// <==        Row: 4, tmp, tmp目录, 2
		// <==        Row: 5, bin, bin目录, 1
		// <==      Total: 5
		// Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@54d1608f]
		// total = 16
		// MyDirectory [directoryId=1, directoryName=home, remark=home目录, userId=1]
		// MyDirectory [directoryId=2, directoryName=usr, remark=usr目录, userId=1]
		// MyDirectory [directoryId=3, directoryName=source, remark=source目录, userId=1]
		// MyDirectory [directoryId=4, directoryName=tmp, remark=tmp目录, userId=2]
		// MyDirectory [directoryId=5, directoryName=bin, remark=bin目录, userId=1]
		// 2022-06-18 13:48:10.591  INFO 1224 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closing ...
		// 2022-06-18 13:48:10.595  INFO 1224 --- [ionShutdownHook] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} closed
		
	}

}