Java中使用MyBatis

目录

mybatis-plus

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可以直接在xml中通过sql语句操作数据库，很灵活。但其操作都要通过sql语句进行，就必须写大量的xml文件，很麻烦。mybatis-plus就很好的解决了这个问题。

官网

mybatis-plus 官方文档

使用

这里我用的数据库是mysql8，新建test数据库，并创建ur表

建表语句

t names utf8mb4;t foreign_key_checks = 0; -- ------------------------------ table structure for ur-- ----------------------------drop table if exists `ur`;create table `ur`  (  `id` varchar(50) character t utf8 collate utf8_general_ci not null comment '主键',  `name` varchar(20) character t utf8 collate utf8_general_ci null default null comment '姓名',  `age` int(0) null default null comment '年龄',  `address` varchar(50) character t utf8 collate utf8_general_ci null default null comment '地址',  primary key (`id`) using btree) engine = innodb character t = utf8 collate = utf8_general_ci row_format = dynamic; t foreign_key_checks = 1;

引入依赖

这里我用的数据库是mysql8

     <parent>        <groupid>org.springframework.boot</groupid>        <artifactid>spring-boot-starter-parent</artifactid>        <version>2.6.3</version>        <relativepath/>    </parent>     <dependencies>        <dependency>            <groupid>org.projectlombok</groupid>            <artifactid>lombok</arti服装店装修图片fac神探高伦布电视剧tid>       消防管理制度 </dependency>        <dependency>            <groupid>org.springframework.boot</groupid>            <artifactid>spring-boot-starter</artifactid>        </dependency>        <dependency>            <groupid>org.springframework.boot</groupid>            <artifactid>spring-boot-devtools</artifactid>            <scope>runtime</scope>            <optional>true</optional>        </dependency>        <dependency>            <groupid>org.springframework.boot</groupid>            <artifactid>spring-boot-starter-test</artifactid>            <scope>test</scope>        </dependency>        <depen情绪的解析dency>            <groupid>org.springframework.boot</groupid>            <artifactid>spring-boot-test</artifactid>        </dependency>        <dependency>            <groupid>junit</groupid>            <artifactid>junit</artifactid>        </dependency>        <dependency>            <groupid>org.springframework</groupid>            <artifactid>spring-test</artifactid>        </dependency>        <dependency>            <groupid>com.baomidou</groupid>            <artifactid>mybatis-plus-boot-starter</artifactid>            <version>3.5.1</version>        </dependency>        <!--druid连接池-->        <dependency>            <groupid>com.alibaba</groupid>            <artifactid>druid-spring-boot-starter</artifactid>            <version>1.1.9</version>        </dependency>        <dependency>            <groupid>mysql</groupid>            <artifactid>mysql-connector-java</artifactid>            <version>8.0.25</version>        </dependency>    </dependencies>

分别创建application.yml及application-dev.yml文件

application.yml

# spring配置spring:  # 环境设置  profiles:    active: dev  # 模板引擎  thymeleaf:    mode: html    encoding: utf-8    # 禁用缓存    cache: fal  # 服务模块  devtools:    restart:      # 热部署开关      enabled: true

application-dev.yml

# 开发环境配置rver:  # 服务器的http端口，默认为80  port: 8081 spring:  datasource:    type: com.alibaba.druid.pool.druiddatasource    driver-class-name: com.mysql.cj.jdbc.driver    druid:      url: jdbc:mysql://localhost:3307/test?uunicode=true&characterencoding=utf8&zerodatetimebehavior=converttonull&ussl=true&rvertimezone=gmt%2b8      urname: root      password: 123456      initial-size: 5      min-idle: 10      max-active: 20      max-wait: 60000      time-between-eviction-runs-millis: 60000      min-evictable-idle-time-millis: 300000      validation-query: lect 'x'      test-while-idle: true      test-on-borrow: fal      test-on-return: fal      pool-prepared-statements: true      max-open-prepared-statements: 50      max-pool-prepared-statement-per-connection-size: 20

编写实体类ur.java,这里用到lombok

@datapublic class ur {    private string id;    private string name;    private integer age;    private string address;}

创建mapper文件夹,并编写mapper 类urmapper.java

public interface urmapper extends bamapper<ur> { }

在 spring boot 启动类中添加@mapperscan注解，扫描 mapper 文件夹：

@springbootapplication@mapperscan("com.mybatisplus.mapper")public class mainapplication {    public static void main(string[] args)    {        springapplication.run(mainapplication.class, args);    }}

添加测试类，进行功能测试：

测试数据插入数据库

    @autowired    private urmapper urmapper;     @test    public void testinrt() {        system.out.println(("----- inrt method test ------"));        ur ur = new ur();        // 自动生成主键,例如550e8400-e29b-11d4-a716-446655440000        string id = uuid.randomuuid().tostring();        string replaceall = id.replaceall("-", "");        //550e8400e29b11d4a716446655440000        ur.tid(replaceall);        ur.tname("张三");        ur.tage(21);        ur.taddress("北京市海淀区");        int inrt = urmapper.inrt(ur);        if(inrt>0){            system.out.println("插入成功："+ur);        }el{            system.out.println("插入失败！");        }    }

测试查询所有

    @autowired    private urmapper us越俎代庖怎么读音ermapper;            @test    public void testlect() {        system.out.println(("----- lectall method test ------"));        list<ur> urlist = urmapper.lectlist(null);        urlist.foreach(system.out::println);    }

测试删除数据

删除姓名等于“张三”的记录

    @autowired    private urmapper urmapper;        @test    public void testdelete() {        system.out.println(("----- delete method test ------"));        lambdaquerywrapper<ur> wrapper = new lambdaquerywrapper<>();        ur ur = new ur();        ur.tname("张三");        wrapper.eq(ur::getname, ur.getname());        int delete = urmapper.delete(wrapper);        if(delete>0){            system.out.println("删除成功："+ur);        }el{            system.out.println("删除失败！");        }    }

测试修改数据

修改前先执行下插入

修改还可以用urmapper.updatebyid(t entity)方法来修改，传入一个实体类

    @autowired    private urmapper urmapper;        @test    public void testupdate() {        system.out.println(("----- update method test ------"));        lambdaquerywrapper<ur> wrapper = new lambdaquerywrapper<>();        ur ur = new ur();        ur.tname("张三");        wrapper.eq(ur::getname, ur.getname());        ur urnew = new ur();        urnew.tname("李四");        int update = urmapper.update(urnew, wrapper);        if(update>0){            system.out.println("修改成功："+ur);        }el{            system.out.println("修改失败！");        }    }

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