mybatis-plus(一)-mybatisplus开发入门

MyBatis-Plus (opens new window)（简称 MP）是一个 MyBatis (opens new window)的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。

mybatis架构

xml 复制代码

<?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.wnhz.third</groupId>
    <artifactId>springboot-mybatisplus</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <project.mybatis-plus.version>3.5.3.1</project.mybatis-plus.version>
        <project.mysql.version>8.0.32</project.mysql.version>
        <project.druid.version>1.2.16</project.druid.version>
        <project.lombok.version>1.18.26</project.lombok.version>
        <project.junit.version>4.12</project.junit.version>
    </properties>

    <parent>
        <artifactId>spring-boot-starter-parent</artifactId>
        <groupId>org.springframework.boot</groupId>
        <version>2.5.6</version>
    </parent>

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

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${project.mysql.version}</version>
        </dependency>

        <!--引入MybatisPlus依赖-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>${project.mybatis-plus.version}</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>${project.druid.version}</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${project.lombok.version}</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${project.junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>
    </build>


</project>

开发mysqlplus程序

application.yml

数据源配置

基本数据源配置： url、username、password、driver-class-name

yml 复制代码

spring:
  datasource:
    druid:
      url: jdbc:mysql://localhost:3306/bookshop_db?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
      username: root
      password: 1234
      driver-class-name: com.mysql.cj.jdbc.Driver

数据源其它配置 inital-size、max-active、min-idle、max-wait等

yml 复制代码

   datasource:
        # 初始化时建立的物理连接数。初始化发生在显式调用init方法，或者第一次getConnection时.
        initial-size: 5
        # 连接池最大物理连接数量。
        max-active: 50
        # 连接池最小物理连接数量。
        min-idle: 5
        # 获取连接时最大等待时间，单位为毫秒。
        # 配置之后，缺省启用公平锁，并发效率会有所下降，若需要可以通过配置useUnfairLock属性为true使用非公平锁。
        max-wait: 6000
        # 是否缓存preparedStatement，也就是PSCache。
        # PSCache对支持游标的数据库性能提升巨大，比如说oracle。在mysql下建议关闭。
        pool-prepared-statements: true
        # 要启用PSCache，其值必须大于0，当大于0时，poolPreparedStatements自动触发修改为true。
        # 在Druid中，不会存在Oracle下PSCache占用内存过多的问题，可以把这个数值配置大一些，比如说100。
        max-pool-prepared-statement-per-connection-size: 20
        # 用来检测连接是否有效的sql，要求是一个查询语句，常用select 'x'。
        # 如果validationQuery为null，testOnBorrow、testOnReturn、testWhileIdle都不会起作用。
        validation-query: select 1 from dual

mybatisplus配置

yml 复制代码

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:/mapper/*.mapper.xml      #xml文件的位置(resources下的mapper文件夹)

实体类

java 复制代码

package com.wnhz.bm.domain.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.math.BigDecimal;
import java.util.Date;

@Data
@NoArgsConstructor
@AllArgsConstructor
@TableName("book_tab")
public class Book {
    @TableId(value = "book_id", type = IdType.AUTO)
    private Long id;

    @TableField("book_title")
    private String title;

    @TableField("book_author")
    private String author;

    @TableField("book_price")
    private BigDecimal price;

    @TableField("book_version")
    private Integer version;//版次

    @JsonFormat(pattern = "yyyy-MM-dd")
    @TableField("book_pubDate")
    private Date pubDate;

    @TableField("book_store")
    private Integer store;

    @TableField("book_imgurl")
    private String imgUrl;

    @TableField("book_weight")
    private BigDecimal weight;

    @TableField("book_introduction")
    private String introduction;

    @TableField("book_sold")
    private Integer ordered;

    @TableField("book_pages")
    private Integer pages;

    @TableField("book_createtime")
    private Date createTime;

    @TableField("book_updatetime")
    private Date updateTime;

    @TableField("book_createby")
    private String createBy;

    @TableField("book_publisher")
    private Long publisher;

    @TableField("book_type")
    private Long type;
}

mapper映射接口

java 复制代码

package com.wnhz.dao;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.wnhz.entity.Book;

@Mapper
public interface IBookDao extends BaseMapper<Book> {
}

service服务接口

java 复制代码

public interface IBookService {
    List<Book> findAllBooks();
    List<Book> findByAuthor(String author);
}

service的实现类

java 复制代码

@Service
public class BookServiceImpl implements IBookService {

    @Autowired
    private IProductDao  dao;

    @Override
    public List<Product> findAllProducts() {
        return dao.selectList(null);
    }

    @Override
    public List<Product> findByName(String name) {
        QueryWrapper<Product> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("name", name);
        return dao.selectList(queryWrapper);
    }
}

或者使用map作为条件

java 复制代码

Map<String,Object> params = new HashMap<>();
params.put("author",author);
return dao.selectByMap(params);

启动类

@MapperScan注解映射接口的包名称。

java 复制代码

package com.wnhz;

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

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

测试类

java 复制代码

package com.wnhz.dao;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.wnhz.entity.Book;
import com.wnhz.service.IBookService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import static org.junit.Assert.*;

@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
public class IBookDaoTest {

    @Autowired
    private IBookService ibs;

    @Test
    public  void testFindAll(){
        System.out.println(ibs.findAllBooks());
    }

    @Test
    public void testFindByAuthor(){

        System.out.println(ibs.findByAuthor("邓墙"));
    }

}