码迷，mamicode.com
首页 > 其他好文 > 详细

【Mybatis-Plus】01 快速上手

时间：2020-07-20 13:31:18      阅读：126      评论：0      收藏：0      [点我收藏+]

标签：list   arc   lower   执行   java   als   hiera   帮助   点击   

【官网快速上手地址】

https://mp.baomidou.com/guide/quick-start.html#%E5%88%9D%E5%A7%8B%E5%8C%96%E5%B7%A5%E7%A8%8B

 

创建一个空的数据库，并插入user表和数据：

DROP TABLE IF EXISTS user;

CREATE TABLE user
(
    id BIGINT(20) NOT NULL COMMENT ‘主键ID‘,
    name VARCHAR(30) NULL DEFAULT NULL COMMENT ‘姓名‘,
    age INT(11) NULL DEFAULT NULL COMMENT ‘年龄‘,
    email VARCHAR(50) NULL DEFAULT NULL COMMENT ‘邮箱‘,
    PRIMARY KEY (id)
);


DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, ‘Jone‘, 18, ‘test1@baomidou.com‘),
(2, ‘Jack‘, 20, ‘test2@baomidou.com‘),
(3, ‘Tom‘, 28, ‘test3@baomidou.com‘),
(4, ‘Sandy‘, 21, ‘test4@baomidou.com‘),
(5, ‘Billie‘, 24, ‘test5@baomidou.com‘);

 

然后使用IDEA创建SpringBoot项目，不需要点击任何工具选项：

进入项目导入pom坐标：

        <!-- JDBC -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <!-- lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!-- mybatis-plus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.2</version>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

 

【application.properties】

配置连接参数：

spring.datasource.driver-class-name = com.mysql.cj.jdbc.Driver
spring.datasource.url = jdbc:mysql://49.234.116.100:3306/mybatis_plus?serverTimezone=GMT
spring.datasource.username = root 
spring.datasource.password = 123456

编写实体类：

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Integer id;
    private String name;
    private Integer age;
    private String email;
}

 

编写User的Mapper接口，使用Mybatis-Plus，将接口继承BaseMapper

public interface UserMapper extends BaseMapper<User> {
    
}

【回顾我的阶段一项目，当时就这么写过一个基本的BaseDao接口...】

CRUD的代码已经由mybatis-plus帮助我们完成了

 

BaseMapper接口的源码：

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package com.baomidou.mybatisplus.core.mapper;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;

public interface BaseMapper<T> extends Mapper<T> {
    int insert(T entity);

    int deleteById(Serializable id);

    int deleteByMap(@Param("cm") Map<String, Object> columnMap);

    int delete(@Param("ew") Wrapper<T> wrapper);

    int deleteBatchIds(@Param("coll") Collection<? extends Serializable> idList);

    int updateById(@Param("et") T entity);

    int update(@Param("et") T entity, @Param("ew") Wrapper<T> updateWrapper);

    T selectById(Serializable id);

    List<T> selectBatchIds(@Param("coll") Collection<? extends Serializable> idList);

    List<T> selectByMap(@Param("cm") Map<String, Object> columnMap);

    T selectOne(@Param("ew") Wrapper<T> queryWrapper);

    Integer selectCount(@Param("ew") Wrapper<T> queryWrapper);

    List<T> selectList(@Param("ew") Wrapper<T> queryWrapper);

    List<Map<String, Object>> selectMaps(@Param("ew") Wrapper<T> queryWrapper);

    List<Object> selectObjs(@Param("ew") Wrapper<T> queryWrapper);

    <E extends IPage<T>> E selectPage(E page, @Param("ew") Wrapper<T> queryWrapper);

    <E extends IPage<Map<String, Object>>> E selectMapsPage(E page, @Param("ew") Wrapper<T> queryWrapper);
}

 

别忘了加持久层注解

技术图片

在Main方法的类上面添加Mapper扫描注解

技术图片

 

测试类：

@SpringBootTest
class MybatisPlusApplicationTests {

    @Autowired // 自动装配
    private UserMapper userMapper;

    @Test
    void contextLoads() {
        // wrapper 是一个封装查询条件的对象，如果不需要条件不就是null
        List<User> userList = userMapper.selectList(null);
        // lambda表达式
        userList.forEach(System.out::print);
    }

}

 

执行结果：

11:02:18.166 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating CacheAwareContextLoaderDelegate from class [org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate]
11:02:18.185 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating BootstrapContext using constructor [public org.springframework.test.context.support.DefaultBootstrapContext(java.lang.Class,org.springframework.test.context.CacheAwareContextLoaderDelegate)]
11:02:18.231 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating TestContextBootstrapper for test class [cn.echo42.MybatisPlusApplicationTests] from class [org.springframework.boot.test.context.SpringBootTestContextBootstrapper]
11:02:18.257 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Neither @ContextConfiguration nor @ContextHierarchy found for test class [cn.echo42.MybatisPlusApplicationTests], using SpringBootContextLoader
11:02:18.263 [main] DEBUG org.springframework.test.context.support.AbstractContextLoader - Did not detect default resource location for test class [cn.echo42.MybatisPlusApplicationTests]: class path resource [cn/echo42/MybatisPlusApplicationTests-context.xml] does not exist
11:02:18.263 [main] DEBUG org.springframework.test.context.support.AbstractContextLoader - Did not detect default resource location for test class [cn.echo42.MybatisPlusApplicationTests]: class path resource [cn/echo42/MybatisPlusApplicationTestsContext.groovy] does not exist
11:02:18.264 [main] INFO org.springframework.test.context.support.AbstractContextLoader - Could not detect default resource locations for test class [cn.echo42.MybatisPlusApplicationTests]: no resource found for suffixes {-context.xml, Context.groovy}.
11:02:18.265 [main] INFO org.springframework.test.context.support.AnnotationConfigContextLoaderUtils - Could not detect default configuration classes for test class [cn.echo42.MybatisPlusApplicationTests]: MybatisPlusApplicationTests does not declare any static, non-private, non-final, nested classes annotated with @Configuration.
11:02:18.329 [main] DEBUG org.springframework.test.context.support.ActiveProfilesUtils - Could not find an ‘annotation declaring class‘ for annotation type [org.springframework.test.context.ActiveProfiles] and class [cn.echo42.MybatisPlusApplicationTests]
11:02:18.456 [main] DEBUG org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider - Identified candidate component class: file [C:\Users\User-Dai\IdeaProjects\Mybatis-Plus\target\classes\cn\echo42\MybatisPlusApplication.class]
11:02:18.457 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Found @SpringBootConfiguration cn.echo42.MybatisPlusApplication for test class cn.echo42.MybatisPlusApplicationTests
11:02:18.630 [main] DEBUG org.springframework.boot.test.context.SpringBootTestContextBootstrapper - @TestExecutionListeners is not present for class [cn.echo42.MybatisPlusApplicationTests]: using defaults.
11:02:18.631 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Loaded default TestExecutionListener class names from location [META-INF/spring.factories]: [org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener, org.springframework.boot.test.mock.mockito.ResetMocksTestExecutionListener, org.springframework.boot.test.autoconfigure.restdocs.RestDocsTestExecutionListener, org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerResetTestExecutionListener, org.springframework.boot.test.autoconfigure.web.servlet.MockMvcPrintOnlyOnFailureTestExecutionListener, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverTestExecutionListener, org.springframework.boot.test.autoconfigure.webservices.client.MockWebServiceServerTestExecutionListener, org.springframework.test.context.web.ServletTestExecutionListener, org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener, org.springframework.test.context.support.DependencyInjectionTestExecutionListener, org.springframework.test.context.support.DirtiesContextTestExecutionListener, org.springframework.test.context.transaction.TransactionalTestExecutionListener, org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener, org.springframework.test.context.event.EventPublishingTestExecutionListener]
11:02:18.660 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Using TestExecutionListeners: [org.springframework.test.context.web.ServletTestExecutionListener@437da279, org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener@23c30a20, org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener@1e1a0406, org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener@3cebbb30, org.springframework.test.context.support.DirtiesContextTestExecutionListener@12aba8be, org.springframework.test.context.transaction.TransactionalTestExecutionListener@290222c1, org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener@67f639d3, org.springframework.test.context.event.EventPublishingTestExecutionListener@6253c26, org.springframework.boot.test.mock.mockito.ResetMocksTestExecutionListener@49049a04, org.springframework.boot.test.autoconfigure.restdocs.RestDocsTestExecutionListener@71a8adcf, org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerResetTestExecutionListener@27462a88, org.springframework.boot.test.autoconfigure.web.servlet.MockMvcPrintOnlyOnFailureTestExecutionListener@82de64a, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverTestExecutionListener@659499f1, org.springframework.boot.test.autoconfigure.webservices.client.MockWebServiceServerTestExecutionListener@51e69659]
11:02:18.667 [main] DEBUG org.springframework.test.context.support.AbstractDirtiesContextTestExecutionListener - Before test class: context [DefaultTestContext@d9345cd testClass = MybatisPlusApplicationTests, testInstance = [null], testMethod = [null], testException = [null], mergedContextConfiguration = [WebMergedContextConfiguration@2d710f1a testClass = MybatisPlusApplicationTests, locations = ‘{}‘, classes = ‘{class cn.echo42.MybatisPlusApplication}‘, contextInitializerClasses = ‘[]‘, activeProfiles = ‘{}‘, propertySourceLocations = ‘{}‘, propertySourceProperties = ‘{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}‘, contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@1f0f1111, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@6e0dec4a, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.web.client.TestRestTemplateContextCustomizer@47d90b9e, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@3d680b5a, org.springframework.boot.test.context.SpringBootTestArgs@1], resourceBasePath = ‘src/main/webapp‘, contextLoader = ‘org.springframework.boot.test.context.SpringBootContextLoader‘, parent = [null]], attributes = map[‘org.springframework.test.context.web.ServletTestExecutionListener.activateListener‘ -> true]], class annotated with @DirtiesContext [false] with mode [null].
11:02:18.725 [main] DEBUG org.springframework.test.context.support.TestPropertySourceUtils - Adding inlined properties to environment: {spring.jmx.enabled=false, org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}

  .   ____          _            __ _ _
 /\\ / ___‘_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | ‘_ | ‘_| | ‘_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  ‘  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.1.RELEASE)

2020-07-20 11:02:19.217  INFO 17456 --- [           main] cn.echo42.MybatisPlusApplicationTests    : Starting MybatisPlusApplicationTests on DESKTOP-SDT4NG3 with PID 17456 (started by User-Dai in C:\Users\User-Dai\IdeaProjects\Mybatis-Plus)
2020-07-20 11:02:19.220  INFO 17456 --- [           main] cn.echo42.MybatisPlusApplicationTests    : No active profile set, falling back to default profiles: default
2020-07-20 11:02:21.126  INFO 17456 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService ‘applicationTaskExecutor‘
 _ _   |_  _ _|_. ___ _ |    _ 
| | |\/|_)(_| | |_\  |_)||_|_\ 
     /               |         
                        3.3.2 
2020-07-20 11:02:22.667  INFO 17456 --- [           main] cn.echo42.MybatisPlusApplicationTests    : Started MybatisPlusApplicationTests in 3.924 seconds (JVM running for 5.415)

2020-07-20 11:02:23.043  INFO 17456 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-07-20 11:02:26.071  INFO 17456 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
User(id=1, name=Jone, age=18, email=test1@baomidou.com)User(id=2, name=Jack, age=20, email=test2@baomidou.com)User(id=3, name=Tom, age=28, email=test3@baomidou.com)User(id=4, name=Sandy, age=21, email=test4@baomidou.com)User(id=5, name=Billie, age=24, email=test5@baomidou.com)
2020-07-20 11:02:26.215  INFO 17456 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
2020-07-20 11:02:26.472  INFO 17456 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.
2020-07-20 11:02:26.473  INFO 17456 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService ‘applicationTaskExecutor‘

Process finished with exit code 0

 

可以看到这里控制台的输出是没有打印SQL执行的，

所以我们需要配置日志输出

【application.properties】

# 日志配置
mybatis-plus.configuration.log-impl = org.apache.ibatis.logging.stdout.StdOutImpl

二次执行：

Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1687eb01] was not registered for synchronization because synchronization is not active
2020-07-20 11:07:10.780  INFO 25940 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-07-20 11:07:12.318  INFO 25940 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
JDBC Connection [HikariProxyConnection@1674550752 wrapping com.mysql.cj.jdbc.ConnectionImpl@594d9f07] will not be managed by Spring
==>  Preparing: SELECT id,name,age,email FROM user 
==> Parameters: 
<==    Columns: id, name, age, email
<==        Row: 1, Jone, 18, test1@baomidou.com
<==        Row: 2, Jack, 20, test2@baomidou.com
<==        Row: 3, Tom, 28, test3@baomidou.com
<==        Row: 4, Sandy, 21, test4@baomidou.com
<==        Row: 5, Billie, 24, test5@baomidou.com
<==      Total: 5
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1687eb01]
User(id=1, name=Jone, age=18, email=test1@baomidou.com)User(id=2, name=Jack, age=20, email=test2@baomidou.com)User(id=3, name=Tom, age=28, email=test3@baomidou.com)User(id=4, name=Sandy, age=21, email=test4@baomidou.com)User(id=5, name=Billie, age=24, email=test5@baomidou.com)
2020-07-20 11:07:12.506  INFO 25940 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
2020-07-20 11:07:12.891  INFO 25940 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.
2020-07-20 11:07:12.892  INFO 25940 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService ‘applicationTaskExecutor‘

Process finished with exit code 0

 

【CRUD基操】

执行插入测试：

    @Test
    void insertUser() {
        int insert = userMapper.insert(
                new User(
                        null,
                        "啊啊啊",
                        22,
                        "1791255334@qq.com"
                )
        );
    }

插入失败：

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: Could not set property ‘id‘ of ‘class cn.echo42.pojo.User‘ with value ‘1285049463613612034‘ Cause: java.lang.IllegalArgumentException: argument type mismatch

最终原因是因为类型不匹配：

java.lang.IllegalArgumentException: argument type mismatch

在我们User对象id属性设置null进行插入时，mybatis会自动生成一个UID插入

但是显然超出Integer的范围，所以改用Long试试

private Long id;

测试结果果然成功：

Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@237f7970] was not registered for synchronization because synchronization is not active
2020-07-20 11:16:52.830  INFO 19932 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-07-20 11:16:54.222  INFO 19932 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
JDBC Connection [HikariProxyConnection@441867003 wrapping com.mysql.cj.jdbc.ConnectionImpl@2fd64b11] will not be managed by Spring
==>  Preparing: INSERT INTO user ( id, name, age, email ) VALUES ( ?, ?, ?, ? ) 
==> Parameters: 1285051019587166210(Long), 啊啊啊(String), 22(Integer), 1791255334@qq.com(String)
<==    Updates: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@237f7970]

2020-07-20 11:16:54.371  INFO 19932 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
2020-07-20 11:16:54.707  INFO 19932 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.
2020-07-20 11:16:54.709  INFO 19932 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService ‘applicationTaskExecutor‘

Process finished with exit code 0

 

数据库查看：

技术图片

 

【主键生成策略】 

自增
uuid
redis
zookeeper
snowflake 雪花算法

似乎Mybatis-Plus默认采用的生成策略是雪花算法

如果要更改策略的话使用@TableId注解更改

技术图片

可以打开看看这个type的枚举类

package com.baomidou.mybatisplus.annotation;

public enum IdType {
    AUTO(0),
    NONE(1),
    INPUT(2),
    ASSIGN_ID(3),
    ASSIGN_UUID(4),
    /** @deprecated */
    @Deprecated
    ID_WORKER(3),
    /** @deprecated */
    @Deprecated
    ID_WORKER_STR(3),
    /** @deprecated */
    @Deprecated
    UUID(4);

    private final int key;

    private IdType(int key) {
        this.key = key;
    }

    public int getKey() {
        return this.key;
    }
}

 

【Mybatis-Plus】01 快速上手

标签：list   arc   lower   执行   java   als   hiera   帮助   点击   

原文地址：https://www.cnblogs.com/mindzone/p/13344056.html
踩
(0)
赞
(0)
   
举报
评论 一句话评论（0）
登录后才能评论！
分享档案
更多>
2021年07月29日 (22)
2021年07月28日 (40)
2021年07月27日 (32)
2021年07月26日 (79)
2021年07月23日 (29)
2021年07月22日 (30)
2021年07月21日 (42)
2021年07月20日 (16)
2021年07月19日 (90)
2021年07月16日 (35)
周排行
mamicode.com排行更多图片
更多
友情链接
兰亭集智   国之画   百度统计   站长统计   阿里云   chrome插件   新版天听网
关于我们 - 联系我们 - 留言反馈
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码！