做外贸哪里网站比较好,在线做头像,app引流推广方法,上海备案证查询网站查询1、Mybatis Plus介绍
Mybatis#xff0c;用过的都知道#xff0c;这里不介绍#xff0c;mybatis plus只是在mybatis原来的基础上做了些改进#xff0c;增强了些功能#xff0c;增强的功能主要为增加更多常用接口方法调用#xff0c;减少xml内sql语句编写#xff0c;也可…1、Mybatis Plus介绍
Mybatis用过的都知道这里不介绍mybatis plus只是在mybatis原来的基础上做了些改进增强了些功能增强的功能主要为增加更多常用接口方法调用减少xml内sql语句编写也可以自定义接口简单的查询、新增和删除只需调用内置接口方法即可有点类似于springdata jpa的方式。
2、插件引入和启动配置
2.1、pom.xml
dependencies
!-- mybatis-plus插的springboot支持 --dependencygroupIdcom.baomidou/groupIdartifactIdmybatis-plus-boot-starter/artifactIdversion3.5.2/version/dependency!-- MySql --dependencygroupIdmysql/groupIdartifactIdmysql-connector-java/artifactIdversion8.0.30/version/dependency!-- 连接池 --dependencygroupIdcom.alibaba/groupIdartifactIddruid/artifactIdversion1.2.15/version/dependency
/dependencies2.2、application.yml配置
server:port: 8080
spring:application:name: mybatisPlusdatasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://127.0.0.1:3306/mybatistest?useUnicodetruecharacterEncodingutf8autoReconnecttrueallowMultiQueriestrueuseSSLfalseusername: liuliupassword: 123456
mybatis:database:type: mysql
mybatis-plus:mapper-locations: classpath*:mapper/*.xmlmapper-locations: 这里配置xxxMapper.xml文件路径的地方静态目录【resources】下如果项目简单不需要用到xml内的查询这里可以省略掉。
2.3、启动入口配置
package com.liuliu.demo;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;SpringBootApplication
//启动前需扫描dao接口文件所对应的包路径加入到bean处理
//这里很重要否则自定义的查询接口无效
MapperScan(com.liuliu.demo.mapper)
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args);}}3、查询
3.1、创建数据表对象
数据表结构
CREATE TABLE tb_user (id int(11) NOT NULL AUTO_INCREMENT,user_name varchar(32) NOT NULL COMMENT 用户名称,password varchar(32) DEFAULT NULL COMMENT 密码,name varchar(64) DEFAULT NULL COMMENT name,age int(11) DEFAULT NULL,email varchar(32) DEFAULT NULL,demp_id int(11) DEFAULT NULL,md5 char(32) DEFAULT NULL,PRIMARY KEY (id)
) ENGINEInnoDB DEFAULT CHARSETutf8;CREATE TABLE demp (id int(11) NOT NULL AUTO_INCREMENT,classname varchar(32) NOT NULL,PRIMARY KEY (id),UNIQUE KEY actable_uni_classname (classname)
) ENGINEInnoDB DEFAULT CHARSETutf8;创建实体类
Data
TableName(tb_user)
public class User {TableId(type IdType.AUTO)private Integer id;private String userName;TableField(select false)private String password;private String name;private Integer age;TableField(value email)private String mail;TableField(exist false)private String address;TableField(value demp_id)private Integer dempId;private String md5;TableField(exist false)private Demp demp;
}Data
public class Demp {TableId(type IdType.AUTO)private Integer id;private String classname;
}创建mapperDao接口
Mapper
Repository
public interface UserMapper extends BaseMapperUser {
}Mapper
Repository
public interface DempMapper extends BaseMapperDemp {
}创建service接口
package com.liuliu.demo.service;public interface UserService extends IServiceUser {
}这里只需演示一个表的查询其它的service就不演示创建了。
3.2、查询数据
先手动创建好数据
创建一个实现查询接口service类
package com.liuliu.demo.service.impl;Service
public class UserServiceImpl extends ServiceImplUserMapper, User implements UserService {Autowiredprivate UserMapper userMapper;public void findUserModule(){//查多条当没查到时返回[]System.out.println(list(query().ge(id, 2).getWrapper()));//只查一条,当没查到时返回nullSystem.out.println(getOne(query().ge(age, 22).orderByDesc(id).getWrapper().last(limit 1)));}创建一个controller类
RestController
public class UserController {Autowiredprivate UserServiceImpl userserviceimpl;GetMapping(findtest)public long findtestmodule(){userserviceimpl.findUserModule();//作为测试效果这里不做数据返回了而是在内部控制台打印return System.currentTimeMillis();}
}控制台输出的结果
[User(id2, userName李四, passwordnull, namelisi, age22, maillisiaa.com, addressnull, dempId2, md5null, dempnull), User(id3, userName王强, passwordnull, namewangqiang, age35, mailwangqq.com, addressnull, dempId1, md5null, dempnull), User(id5, userName川建国, passwordnull, nameDonaldTrump, age83, maildonaldqq.com, addressnull, dempId2, md5null, dempnull)]
User(id5, userName川建国, passwordnull, nameDonaldTrump, age83, maildonaldqq.com, addressnull, dempId2, md5null, dempnull)是不是很解单新增和删除数据方法自己去试试
this.save(user);
userMapper.deleteById(id);3.3、关联查询
通过Mybatis plus自带方法来查关联表暂时好像还不支持但可以使用xml文件内的sql语法来创建
3.3.1、自定义接口方法
package com.liuliu.demo.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.liuliu.demo.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;import java.util.List;Mapper
Repository
public interface UserMapper extends BaseMapperUser {User getUserById(Integer id);ListUser getUserAll();
}3.3.2、创建userMapper.xml
路径resources/mapper/userMapper.xml
?xml version1.0 encodingUTF-8?
!DOCTYPE mapper PUBLIC -//mybatis.org//DTD Mapper 3.0//EN http://mybatis.org/dtd/mybatis-3-mapper.dtd
mapper namespacecom.liuliu.demo.mapper.UserMappersql idfieldAlltb_user.*,demp.id as dempId,demp.classname/sqlresultMap iduserMap typecom.liuliu.demo.pojo.Userid propertyid columnid /result propertyuserName columnuser_name /result propertyname columnname /result propertyage columnage /result propertypassword columnpassword /result propertymail columnemail /result propertydempId columndemp_id /association propertydemp javaTypecom.liuliu.demo.pojo.Dempresult propertyid columndempId /result propertyclassname columnclassname //association/resultMapselect idgetUserById resultMapuserMap parameterTypeIntegerselect include refidfieldAll/ from tb_user join demp on tb_user.demp_iddemp.id where tb_user.id#{id}/selectselect idgetUserAll resultMapuserMapselect include refidfieldAll/ from tb_user join demp on tb_user.demp_iddemp.id/select
/mapper3.3.3、实现关联查询
UserServiceImpl.java内添加查询方法
public User findByid(Integer id){return userMapper.getUserById(id);
}Override
public ListUser findUserAll() {return userMapper.getUserAll();
}控制器内添加查询对接
GetMapping(/findById)public User findById(RequestParam(name id) Integer id){return userserviceimpl.findByid(id);}GetMapping(/findUserAll)public ListUser findUserAll(){return userserviceimpl.findUserAll();}demp表数据
访问结果 http://127.0.0.1:8080/findById?id5
{id: 5,userName: 川建国,password: fjiewofdsafadfkewok,name: DonaldTrump,age: 83,mail: donaldqq.com,address: null,dempId: 2,md5: null,demp: {id: 2,classname: 技术部}
}http://127.0.0.1:8080/findUserAll
[{id: 1,userName: 张三,password: 123456,name: zhangsan,age: 20,mail: daaa.com,address: null,dempId: 1,md5: null,demp: {id: 1,classname: 财务部}},{id: 2,userName: 李四,password: 123456,name: lisi,age: 22,mail: lisiaa.com,address: null,dempId: 2,md5: null,demp: {id: 2,classname: 技术部}},{id: 3,userName: 王强,password: fjeiwofjdksajl,name: wangqiang,age: 35,mail: wangqq.com,address: null,dempId: 1,md5: null,demp: {id: 1,classname: 财务部}},{id: 5,userName: 川建国,password: fjiewofdsafadfkewok,name: DonaldTrump,age: 83,mail: donaldqq.com,address: null,dempId: 2,md5: null,demp: {id: 2,classname: 技术部}}
]4、SpringBoot启动时自动更新数据表
自动更新表结构在团队开发中非常重要否则在开发管理上很麻烦并且增加正式环境中的运维难度每次新增一个表或更改一个表结构都需要单独在数据库中去操作这不符合实际开发应用。 Mybatis plus自动更新数据表结构在设置上相比springdata jpa要复杂一些需要先在pom中引入一个包然后在yml配置文件中配置相关启动开关还需在入口处配置实体扫描。
4.1、pom.xml引入相关包
dependencygroupIdcom.gitee.sunchenbin.mybatis.actable/groupIdartifactIdmybatis-enhance-actable/artifactIdversion1.1.1.RELEASE/version
/dependency4.2、application.yml增加内容
mybatis:table:auto: update #update: 数据表实体类只要有变动就会对数据表实施更改操作包括删除表、新增表、更新表字段等。model:pack: com.liuliu.demo.pojo #扫描数据实体位置database:type: mysql #数据库类型
mybatis-plus:
#前部分为自动更新需用到的查询xmlmapper-locations: com/gitee/sunchenbin/mybatis/actable/mapping/*/*.xml,classpath*:mapper/*.xml4.3、入口启动文件配置
package com.liuliu.demo;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;SpringBootApplication
MapperScan({com.gitee.sunchenbin.mybatis.actable.dao.*, com.liuliu.demo.mapper})
ComponentScan({com.gitee.sunchenbin.mybatis.actable.manager.*, com.liuliu.demo.*})
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args);}
}注意ComponentScan前段是mybatis自带的没有是会报错的会报找不到对应的bean后段是当前项目根目录包如果不写会访问不到任何控制器因为这里的扫描会导致后面的been添加无效。
4.4、数据实体配置
实体类需要添加对应的注解否则前面做了那么多也没有用。 主要有: Table IsKey IsAutoIncrement Column Unique Index
User.java
package com.liuliu.demo.pojo;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.gitee.sunchenbin.mybatis.actable.annotation.*;
import lombok.Data;Data
TableName(tb_user)
Table(name tb_user)
public class User {TableId(type IdType.AUTO)IsKeyIsAutoIncrementColumnprivate Integer id;//这里有个bug说明下这个length默认是255,设置length时如果不设置type,是无效的最后查看数据表结果还是255Column(name user_name, length 32, comment 用户名称, type varchar, isNull false)private String userName;TableField(select false)Column(name password, length 32, comment 密码, type varchar)private String password;Column(name name, length 64, comment name, type varchar)private String name;Columnprivate Integer age;TableField(value email)Column(name email, length 32, type varchar)private String mail;TableField(exist false)private String address;TableField(value demp_id)Column(name demp_id)private Integer dempId;Column(type char, length 32)private String md5;TableField(exist false)private Demp demp;
}
Demp.java
package com.liuliu.demo.pojo;import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.gitee.sunchenbin.mybatis.actable.annotation.*;
import lombok.Data;Data
Table(name demp)
public class Demp {TableId(type IdType.AUTO)ColumnIsAutoIncrementIsKeyprivate Integer id;Column(type varchar, length 32, isNull false)Uniqueprivate String classname;
}4.5、重启springboot应用查看效果
重启前先清空数据表 :: Spring Boot :: (v2.3.12.RELEASE)2023-07-31 16:49:42.628 INFO 17156 --- [ main] com.liuliu.demo.DemoApplication : Starting DemoApplication on yonnry with PID 17156 (C:\src\test\mybatisPlusDemo\target\classes started by yongp in C:\src\test\mybatisPlusDemo)
2023-07-31 16:49:42.629 INFO 17156 --- [ main] com.liuliu.demo.DemoApplication : No active profile set, falling back to default profiles: default
2023-07-31 16:49:42.669 WARN 17156 --- [kground-preinit] o.s.h.c.j.Jackson2ObjectMapperBuilder : For Jackson Kotlin classes support please add com.fasterxml.jackson.module:jackson-module-kotlin to the classpath
2023-07-31 16:49:43.198 INFO 17156 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2023-07-31 16:49:43.203 INFO 17156 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2023-07-31 16:49:43.203 INFO 17156 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.46]
2023-07-31 16:49:43.241 INFO 17156 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2023-07-31 16:49:43.241 INFO 17156 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 575 ms
2023-07-31 16:49:43.422 WARN 17156 --- [ main] c.b.m.core.injector.AbstractMethod : [com.liuliu.demo.mapper.DempMapper.selectById] Has been loaded by XML or SqlProvider or Mybatiss Annotation, so ignoring this injection for [class com.baomidou.mybatisplus.core.injector.methods.SelectById]_ _ |_ _ _|_. ___ _ | _
| | |\/|_)(_| | |_\ |_)||_|_\ / | 3.5.2
2023-07-31 16:49:43.742 INFO 17156 --- [ main] c.g.s.m.a.m.handler.StartUpHandlerImpl : databaseTypemysql开始执行mysql的处理方法
2023-07-31 16:49:43.749 INFO 17156 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting...
2023-07-31 16:49:43.818 INFO 17156 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed.
file类型的扫描:com.liuliu.demo.pojo
2023-07-31 16:49:43.907 INFO 17156 --- [ main] s.m.a.m.s.SysMysqlCreateTableManagerImpl : 开始创建表tb_user
2023-07-31 16:49:43.958 INFO 17156 --- [ main] s.m.a.m.s.SysMysqlCreateTableManagerImpl : 完成创建表tb_user
2023-07-31 16:49:43.958 INFO 17156 --- [ main] s.m.a.m.s.SysMysqlCreateTableManagerImpl : 开始创建表demp
2023-07-31 16:49:43.973 INFO 17156 --- [ main] s.m.a.m.s.SysMysqlCreateTableManagerImpl : 完成创建表demp
2023-07-31 16:49:43.973 INFO 17156 --- [ main] s.m.a.m.s.SysMysqlCreateTableManagerImpl : 开始创建表demp中的唯一约束actable_uni_classname
2023-07-31 16:49:43.982 INFO 17156 --- [ main] s.m.a.m.s.SysMysqlCreateTableManagerImpl : 完成创建表demp中的唯一约束actable_uni_classname
2023-07-31 16:49:44.064 INFO 17156 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService applicationTaskExecutor
2023-07-31 16:49:44.100 INFO 17156 --- [ main] o.s.b.a.w.s.WelcomePageHandlerMapping : Adding welcome page: class path resource [static/index.html]
2023-07-31 16:49:44.154 INFO 17156 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path
2023-07-31 16:49:44.159 INFO 17156 --- [ main] com.liuliu.demo.DemoApplication : Started DemoApplication in 1.738 seconds (JVM running for 2.192)注意看已成功启动console中有提示“完成创建数据表***”修改表就不演示了原理是一样的。
5、结束
源码下载https://download.csdn.net/download/u012029030/88136220 感谢观看以上是我对springboot总结的经验如有什么疑问或不同意见欢迎留言。
