1.1 What is Mybatis-Plus

Plus-MyBatis (abbreviated MP) is a MyBatis enhancement tools, based on MyBatis only enhance not changed , to simplify development, increase efficiency and health.

1.2 Why learn Mybatis-Plus

We have learned Mybatis this framework, we only need to define the abstract interface dao layer, based on the characteristics Mybatis zero achieve, you can achieve crud operation of the database.

The following two interfaces:

UserMapper Interface

public interface UserMapper {

int deleteByPrimaryKey(Long id);

int insert(User user);

List<User> selectList();

User selectByPrimaryKey(Long id);

}

OrderMapper Interface

public interface OrderMapper {

int deleteByPrimaryKey(Long id);

int insert(Order order);

List<Order> selectList();

User selectByPrimaryKey(Long id);

}

In the above two business interface, we found that: they define a set of similar crud method.

In more type of business, when this group of functionally similar interface methods we need to repeat the definition.

How to solve this problem?

Use Mybatis-plus tools, we only need to define the abstract interface we inherit a common BaseMapper <T> interface, you can get a common set of crud way to operate the database! ! !

When using Mybatis-plus, you do not even need any xml mapping files or annotations interface method, the real realization dao layer zero.

1.3 Mybatis-Plus Summary

Mybatis-Plus only on the basis of Mybatis on the realization of the enhancements, allowing developers to more simple and efficient.

Mybatis-Plus does not modify any of the characteristics Mybatis! ! !

2 start example

2.1 Requirements

Use Mybatis-Plus achieve crud operations for the user.

2.2 Configuration step described

(1) build environment (creating a project, import the package)

(2) Configuration Mybaits-Plus (Spring-based implementation)

(3) writing test code

2.3 Configuration Step

2.3.1 The first step: build environment

2.3.1.1 premise

We have created a database environment:

Construction of the table statement:

CREATE TABLE `tb_user` (

`id` bigint(20) NOT NULL COMMENT '主键ID',

`name` varchar(30) DEFAULT NULL COMMENT '姓名',

`Age` int (11) DEFAULT NULL COMMENT 'Age'

`Email` varchar (50) DEFAULT NULL COMMENT 'mailbox',

PRIMARY KEY (`id`)

)

2.3.1.2 Description

(1) Mybatis-Plus does not provide a separate jar package, but through Maven (or Gradle) to manage dependency jar. This tutorial requires the use Maven to build the project.

(2) Mybatis-Plus is based on the Spring Framework implementation, the use Mybatis-Plus, you must import the relevant dependent Spring.

2.3.1.3 Creating project

2.3.1.4 add dependencies

修改pom.xml文件，添加Mybatis-Plus相关依赖：

<groupId>com.baomidou</groupId>

<artifactId>mybatis-plus</artifactId>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-context</artifactId>

<version>4.3.16.RELEASE</version>

</dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

</dependency>

<groupId>com.alibaba</groupId>

<artifactId>druid</artifactId>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-jdbc</artifactId>

<version>4.3.16.RELEASE</version>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-test</artifactId>

<version>4.3.16.RELEASE</version>

</dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-aspects</artifactId>

<version>4.3.16.RELEASE</version>

</dependency>

</dependencies>

2.3.2 第二步：创建User实体类

说明：使用Mybatis-Plus可以不使用xml文件，而是基于一组注解来解决实体类和数据库表的映射问题。

@TableName(value="tb_user")	指定对应的表，表名和类名一致时，可以省略value属性。
@TableId	指定表的主键。Value属性指定表的主键字段，和属性名一致时，可以省略。Type指定主键的增长策略。
@TableField	指定类的属性映射的表字段，名称一致时可以省略该注解。

User类如下：

package cn.gzsxt.mp.pojo;

import com.baomidou.mybatisplus.annotations.TableField;

import com.baomidou.mybatisplus.annotations.TableId;

import com.baomidou.mybatisplus.annotations.TableName;

import com.baomidou.mybatisplus.enums.IdType;

@TableName("tb_user")

public class User {

@TableId(value = "id", type = IdType.AUTO)

private Long id; //bigint(20) NOT NULL COMMENT '主键ID',

@TableField(value = "name")

private String name; //varchar(30) DEFAULT NULL COMMENT '姓名',

private String age; //int(11) DEFAULT NULL COMMENT '年龄',

private String email; //varchar(50) DEFAULT NULL COMMENT '邮箱',

//补全get、set方法

}

2.3.3 第三步：创建UserMapper接口

说明：继承BaseMapper公共接口即可。

package cn.gzsxt.mp.mapper;

import com.baomidou.mybatisplus.mapper.BaseMapper;

import cn.gzsxt.mp.pojo.User;

public interface UserMapper extends BaseMapper<User>{

}

2.3.4 第四步：Mybatis-Plus整合Spring

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd

http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd

http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">

<context:component-scan base-package="cn.gzsxt.mp"/>

</bean>

<!-- 2、mybatis-plus整合Spring

任何的数据库的框架，要使用spring的事物代理，必须使用spring提供的数据源，必须整合spring才可以使用

-->

<list>

</bean>

</list>

</property>

</bean>

</bean>

</bean>

<!--

AUTO->`0`("数据库ID自增")

INPUT->`1`(用户输入ID")

ID_WORKER->`2`("全局唯一ID")

UUID->`3`("全局唯一ID")

-->

</bean>

<tx:annotation-driven/>

</beans>

2.3.5 第五步：编写测试代码

package cn.gzsxt.mp.test;

import java.util.List;

import org.apache.ibatis.session.RowBounds;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.test.context.ContextConfiguration;

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import com.baomidou.mybatisplus.mapper.EntityWrapper;

import cn.gzsxt.mp.mapper.UserMapper;

import cn.gzsxt.mp.pojo.User;

@RunWith(SpringJUnit4ClassRunner.class)

@ContextConfiguration(locations={"classpath:spring-data.xml"})

@ComponentScan(basePackages={"cn.gzsxt.mp"})

public class UserMapperTEST {

@Autowired

private UserMapper userMapper;

//插入一条记录

@Test

public void insert(){

User user = new User();

user.setAge(18);

user.setEmail("[email protected]");

user.setName("张三");

userMapper.insert(user);

}

//根据id查询

@Test

public void selectById(){

User user = userMapper.selectById(1);

System.out.println("用户id："+user.getId()+"，用户姓名："+user.getName()+"，用户邮箱："+user.getEmail());

}

//根据用户名查找

@Test

public void selectByName(){

EntityWrapper<User> wrapper = new EntityWrapper<>();

wrapper.eq("name", "张三");

List<User> users = userMapper.selectList(wrapper);

for (User user : users) {

System.out.println("用户id："+user.getId()+"，用户姓名："+user.getName()+"，用户邮箱："+user.getEmail());

}

//查询用户列表

@Test

public void selectAll(){

List<User> users = userMapper.selectList(null);

for (User user : users) {

System.out.println("用户id："+user.getId()+"，用户姓名："+user.getName()+"，用户邮箱："+user.getEmail());

}

//分页查询，第2页，每页3条

@Test

public void selectAndPage(){

RowBounds rowBounds = new RowBounds((2-1)*3, 3);

List<User> users = userMapper.selectPage(rowBounds, null);

for (User user : users) {

System.out.println("用户id："+user.getId()+"，用户姓名："+user.getName()+"，用户邮箱："+user.getEmail());

}

//模糊查询

@Test

public void selectByLike(){

EntityWrapper<User> wrapper = new EntityWrapper<>();

wrapper.like("name", "%张%");

List<User> users = userMapper.selectList(wrapper);

for (User user : users) {

System.out.println("用户id："+user.getId()+"，用户姓名："+user.getName()+"，用户邮箱："+user.getEmail());

}

mybatis_plus

1.1 What is Mybatis-Plus

1.2 Why learn Mybatis-Plus

1.3 Mybatis-Plus Summary

2 start example

2.1 Requirements

2.2 Configuration step described

2.3 Configuration Step

2.3.1 The first step: build environment

2.3.1.1 premise

2.3.1.2 Description

2.3.1.3 Creating project

2.3.1.4 add dependencies

2.3.2 第二步：创建User实体类

2.3.3 第三步：创建UserMapper接口

2.3.4 第四步：Mybatis-Plus整合Spring

2.3.5 第五步：编写测试代码

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