mybatis实践篇（二）

自定义类型处理器（TypeHandler）

实体

package com.wyl.mybatis.entity;

import java.util.Date;

/**
 * @Description 省市区-字典
 * @Author wuyilong
 * @Date 2024-02-26
 */

public class FullCity {
    private static final long serialVersionUID = 1L;
    /**
     * 主键ID
     */
    private Long id;
    /**
     * 名称
     */
    private String name;
    /**
     * 区域码
     */
    private String code;

    /**
     * 全名称
     */
    private String fullName;

    /**
     * 创建时间
     */
    private String createTime;


    public static long getSerialVersionUID() {
        return serialVersionUID;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }


    public String getCreateTime() {
        return createTime;
    }

    public void setCreateTime(String createTime) {
        this.createTime = createTime;
    }
}

运行程序

package com.wyl.mybatis.demo;

import com.wyl.mybatis.config.SqlSessionFactoryConfig;
import com.wyl.mybatis.entity.FullCity;
import com.wyl.mybatis.mapper.FullCityMapper;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

/**
 * @Description
 * @Author WuYiLong
 * @Date 2024/3/14 14:47
 */
public class TypeHandlerDemo {

    private final static Logger log = LoggerFactory.getLogger(TypeHandlerDemo.class);

    public static void main(String[] args) throws IOException {
        SqlSessionFactory sqlSessionFactory = SqlSessionFactoryConfig.buildSqlSessionFactory();
        try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
            FullCityMapper mapper = sqlSession.getMapper(FullCityMapper.class);
            FullCity fullCity = mapper.selectByName("广东省");
            log.info("数据json：{}", fullCity.getCreateTime());
        }
    }
}

类型处理器

package com.wyl.mybatis.typehandler;

import cn.hutool.core.date.DateUtil;
import cn.hutool.json.JSONUtil;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;

import java.sql.*;
import java.util.Date;

/**
 * @Description
 * @Author WuYiLong
 * @Date 2024/3/14 15:18
 */
public class DateToStringTypeHandler extends BaseTypeHandler {
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, Object parameter, JdbcType jdbcType) throws SQLException {

    }

    @Override
    public String getNullableResult(ResultSet rs, String columnName) throws SQLException {
        Timestamp timestamp = rs.getTimestamp(columnName);
        if (timestamp != null) {
            return DateUtil.format(new Date(timestamp.getTime()),"yyyy-MM-dd HH:mm:dd.SSSSSS");
        }
        return null;
    }

    @Override
    public Object getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        return null;
    }

    @Override
    public Object getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        return null;
    }
}

mybatis-config.xml

 <typeHandlers>
        <package name="com.wyl.mybatis.typehandler"/>
<!--        <typeHandler handler="com.wyl.mybatis.typehandler.DateToStringTypeHandler" javaType="date" jdbcType="DATE"/>-->
    </typeHandlers>

由上面可以知道：通过自定义类型转换器，java类型和mysql类型可以无缝转换。

mybatis集成springboot

maven设置

springboot: v2.7.18
mybatis-spring-boot-starter: v2.3.2

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.wyl</groupId>
    <artifactId>mybatis-springboot-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.3.2</version>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <version>8.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.30</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.8.26</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.7.18</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

        </dependencies>
    </dependencyManagement>
    <build>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version> <!-- 这里可以选择合适的版本 -->
                <configuration>
                    <source>1.8</source> <!-- 这里指定源代码的Java版本 -->
                    <target>1.8</target> <!-- 这里指定生成字节码的Java版本 -->
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

配置文件yml

server:
  port: 8784

spring:
  profiles:
    active: dev
  datasource:
    url: jdbc:mysql://localhost:3306/blog?useUnicode=true&characterEncoding=utf-8&autoReconnect=true&serverTimezone=GMT%2B8
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: 123456
    hikari:
      maximum-pool-size: 15 #最大连接数,默认值10.
      minimum-idle: 5 #最小空闲连接，默认值10.
      connection-timeout: 60000 #连接超时时间(毫秒),默认值30秒.
      #空闲连接超时时间，默认值600000(10分钟),只有空闲连接数大于最大连接数且空闲时间超过该值，才会被释放
      #如果大于等于 max-lifetime 且 max-lifetime>0,则会被重置为0.
      idle-timeout: 600000
      max-lifetime: 1800000 #连接最大存活时间,默认值30分钟.设置应该比mysql设置的超时时间短
      connection-test-query: select 1 #连接测试查询
      auto-commit: true
      pool-name: HikariCP # 连接池名称

# mybatis
mybatis:
  mapper-locations: classpath:/mapper/**
  type-aliases-package: com.wyl.boot.entity

demo结构

启动完成

上面已经完成了mybatis和springboot的集成，包括一些主要的启动配置、文件夹的分布、maven包的下载

多数据源配置

数据库配置文件

# mysql
db.username=root
db.password=root
db.driver=com.mysql.cj.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/blog?zeroDateTimeBehavior=CONVERT_TO_NULL&useUnicode=true&characterEncoding=utf-8&autoReconnect=true&serverTimezone=GMT%2B8


# pgsql
db1.username=postgres
db1.password=1234
db1.driver=org.postgresql.Driver
db1.url=jdbc:postgresql://127.0.0.1:5432/postgres?reWriteBatchedInserts=true&stringtype=unspecified

mybatis的配置文件

 <!-- 环境：配置mybatis的环境 -->
    <environments default="development">
        <!-- 环境变量：可以配置多个环境变量，比如使用多数据源时，就需要配置多个环境变量 -->
        <environment id="development">
            <!-- 事务管理器 -->
            <transactionManager type="jdbc">
            </transactionManager>
            <!-- 数据源 -->
            <dataSource type="POOLED">
                <property name="driver" value="${db.driver}"/>
                <property name="url" value="${db.url}"/>
                <property name="username" value="${db.username}"/>
                <property name="password" value="${db.password}"/>
            </dataSource>

        </environment>
        <environment id="pgsql">
            <transactionManager type="jdbc"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${db1.driver}"/>
                <property name="url" value="${db1.url}"/>
                <property name="username" value="${db1.username}"/>
                <property name="password" value="${db.password}"/>
            </dataSource>
        </environment>
    </environments>

实体类

package com.wyl.mybatis.entity;

/**
 * @Description 省市区-字典
 * @Author wuyilong
 * @Date 2024-02-26
 */
public class FullCity {

    private static final long serialVersionUID = 1L;

    /**
     * 主键ID
     */
    private Long id;

    /**
     * 名称
     */
    private String name;

    /**
     * 区域码
     */
    private String code;

    /**
     * 全名称
     */
    private String fullName;

    /**
     * 创建时间
     */
    private String createTime;



    public static long getSerialVersionUID() {
        return serialVersionUID;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }


    public String getCreateTime() {
        return createTime;
    }

    public void setCreateTime(String createTime) {
        this.createTime = createTime;
    }
}

package com.wyl.mybatis.entity;

/**
 * @Description
 * @Author WuYiLong
 * @Date 2024/3/22 21:47
 */
public class User {
    /**
     * 主键id
     */
    private Long id;
    /**
     * 用户名
     */
    private String username;
    /**
     * 密码
     */
    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;
    }
}

mapper接口


/**
 * @Description
 * @Author WuYiLong
 * @Date 2024/3/22 21:48
 */
@Mapper
public interface UserMapper {

    /**
     * 列表查询
     * @return
     */
    @Select("select * from public.user")
    List<User> selectList();

}

package com.wyl.mybatis.mapper;

import com.wyl.mybatis.entity.FullCity;
import com.wyl.mybatis.page.Page;
import com.wyl.mybatis.req.FullCityReq;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/**
* @Description 省市区-字典
* @Author wuyilong
* @Date 2024-02-26
*/
@Mapper
public interface FullCityMapper {

    /**
     * 根据名称查询
     * @param name
     * @return
     */
    FullCity selectByName(@Param("name") String name);

    /**
     * 根据名称和code查询
     * @param name
     * @param code
     * @return
     */
    @Select(value = "select * from d_full_city where name = #{name} and code = #{code}")
    FullCity selectByNameAndCode(@Param("name") String name,@Param("code") String code);

    /**
     * 查询省市区
     * @param fullCityReq
     * @return
     */
    @Select(value = "select * from d_full_city where name = #{fullCityReq.name}")
    FullCity selectFullCity(@Param("fullCityReq") FullCityReq fullCityReq);

    /**
     * 省市区模糊查询
     * @param name
     * @return
     */
    @Select(value = "select * from d_full_city where name regexp #{name}")
    List<FullCity> selectFullCityLikeName(@Param("name")  String name);

    /**
     * 分页
     * @param page
     * @return
     */
    @Select("select * from d_full_city")
    List<FullCity> selectFullCityPage(@Param("page") Page page);

    /**
     * 统计表的数量
     * @param table
     * @return
     */
    @Select("select count(*) count from #{table}")
    Integer countTable(@Param("table") String table);
}

数据库加载配置文件

package com.wyl.mybatis.config;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

/**
 * @Description
 * @Author WuYiLong
 * @Date 2024/3/14 9:43
 */
public class SqlSessionFactoryConfig {

    /**
     * 默认配置
     * @return
     * @throws IOException
     */
    public static SqlSessionFactory buildSqlSessionFactory() throws IOException {
        // 读取mybatis的配置文件
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        // 通过SqlSessionFactoryBuilder 的 build 方法用于解析配置文件并创建 SqlSessionFactory 对象。
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        return sqlSessionFactory;
    }

    /**
     * 多环境配置
     * @param environment
     * @return
     * @throws IOException
     */
    public static SqlSessionFactory buildSqlSessionFactoryEnv(String environment) throws IOException {
        // 读取mybatis的配置文件
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        // 通过SqlSessionFactoryBuilder 的 build 方法用于解析配置文件并创建 SqlSessionFactory 对象。
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream,environment);
        return sqlSessionFactory;
    }
}

package com.wyl.mybatis.demo;

import com.wyl.mybatis.config.SqlSessionFactoryConfig;
import com.wyl.mybatis.entity.FullCity;
import com.wyl.mybatis.entity.User;
import com.wyl.mybatis.mapper.FullCityMapper;
import com.wyl.mybatis.mapper.UserMapper;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.List;

/**
 * @Description
 * @Author WuYiLong
 * @Date 2024/3/22 21:16
 */
public class MoreDataSource {

    private static final Logger log = LoggerFactory.getLogger(MoreDataSource.class);

    public static void main(String[] args) throws IOException {
        // mysql
        SqlSessionFactory sqlSessionFactory = SqlSessionFactoryConfig.buildSqlSessionFactory();
        try (SqlSession sqlSession = sqlSessionFactory.openSession()) {

            FullCityMapper mapper = sqlSession.getMapper(FullCityMapper.class);
            FullCity fullCity = mapper.selectByName("广东省");
            System.out.println("区域名称：" + fullCity.getFullName());
        }

        // postgresql
        SqlSessionFactory pgsql = SqlSessionFactoryConfig.buildSqlSessionFactoryEnv("pgsql");
        try (SqlSession sqlSession = pgsql.openSession()) {
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> users = mapper.selectList();
            for (User user : users) {
                log.info("用户名称：{},密码：{}",user.getUsername(),user.getPassword());
            }
        }

    }
}