Java：MyBatis-Plus内置SQL注入器的使用和自定义SQL注入器

环境准备

1、完整依赖 pom.xml

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.7.7</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>1.8</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>com.baomidou</groupId>
			<artifactId>mybatis-plus-boot-starter</artifactId>
			<version>3.5.2</version>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<scope>runtime</scope>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<excludes>
						<exclude>
							<groupId>org.projectlombok</groupId>
							<artifactId>lombok</artifactId>
						</exclude>
					</excludes>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

2、数据库配置 application.yml

# DataSource Config
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/data?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai
    username: root
    password: 123456

mybatis-plus:
  configuration:
    # 开启SQL语句打印
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  global-config:
    db-config:
      # 自增主键策略
      id-type: AUTO

3、建表语句

CREATE TABLE `tb_user` (
  `id` int unsigned NOT NULL AUTO_INCREMENT COMMENT '主键',
  `username` varchar(128) NOT NULL COMMENT '用户名',
  `phone` varchar(32) NOT NULL DEFAULT '' COMMENT '手机号',
  `sex` char(1) NOT NULL DEFAULT '' COMMENT '性别',

  `create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `update_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
  `deleted` tinyint NOT NULL DEFAULT '0' COMMENT '1、删除 0、未删除',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci COMMENT='用户表';

4、实体类

package com.example.demo.entity;

import com.baomidou.mybatisplus.annotation.*;
import lombok.Data;
import lombok.experimental.Accessors;

import java.io.Serializable;
import java.time.LocalDateTime;

@Data
@Accessors(chain = true)
@TableName("tb_user")
public class UserDO implements Serializable {
    
    

    private static final long serialVersionUID = 1L;

    /**
     * 主键
     */
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    /**
     * 用户名
     */
    @TableField("username")
    private String username;

    /**
     * 手机号
     */
    @TableField("phone")
    private String phone;

    /**
     * 性别
     */
    @TableField("sex")
    private String sex;

    /**
     * 创建时间
     */
    @TableField(value = "create_time", fill = FieldFill.INSERT)
    private LocalDateTime createTime;

    /**
     * 更新时间
     */
    @TableField(value = "update_time", fill = FieldFill.INSERT_UPDATE)
    private LocalDateTime updateTime;

    /**
     * 1、删除 0、未删除
     */
    @TableField(value = "deleted", fill = FieldFill.INSERT)
    private Integer deleted;
}

使用内置扩展SQL注入器

Mybatis-Plus默认不支持空值更新，可以通过注入内置扩展SQL注入器实现空值更新

自带扩展SQL注入器

AlwaysUpdateSomeColumnById : 根据id更新字段(全量更新不忽略null字段),updateById默认会自动忽略实体中null值字段。
InsertBatchSomeColumn : 真实批量插入,saveBatch其实是伪批量插入。
LogicDeleteBatchByIds : 逻辑删除增加填充功能,比如删除的时候填充更新时间、更新人。
Upsert : 插入一条数据（选择字段插入）。

1、SQL注入器全局配置

package com.example.demo.config;

import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.injector.DefaultSqlInjector;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.extension.injector.methods.AlwaysUpdateSomeColumnById;
import com.baomidou.mybatisplus.extension.injector.methods.InsertBatchSomeColumn;
import com.example.demo.mybatisplus.methods.FindAll;
import org.springframework.stereotype.Component;

import java.util.List;

/**
 * SQL注入器全局配置
 */
@Component
public class MySqlInjector extends DefaultSqlInjector {
    
    
    @Override
    public List<AbstractMethod> getMethodList(Class<?> mapperClass, TableInfo tableInfo) {
    
    
        List<AbstractMethod> methodList = super.getMethodList(mapperClass, tableInfo);

        /**
         * 把两个扩展内置扩展SQL注入器注入
         */
        methodList.add(new InsertBatchSomeColumn(i -> i.getFieldFill() != FieldFill.UPDATE));
        methodList.add(new AlwaysUpdateSomeColumnById(i -> i.getFieldFill() != FieldFill.INSERT));

        return methodList;
    }
}

2、自定义Mapper

package com.example.demo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

/**
 * 自定义Mapper
 * @param <T>
 */
public interface MyBaseMapper<T> extends BaseMapper<T> {
    
    

    /**
     * 全字段更新，不会忽略null值
     *
     * @param entity 实体对象
     */
    int alwaysUpdateSomeColumnById(@Param("et") T entity);

    /**
     * 全量插入,等价于insert
     *
     * @param entityList 实体集合
     */
    int insertBatchSomeColumn(List<T> entityList);
}

3、继承MyBaseMapper

package com.example.demo.mapper;

import com.example.demo.entity.UserDO;
import org.apache.ibatis.annotations.Mapper;

/**
 *  通用mapper接口，以后创建其他mapper接口时，不再继承BaseMapper，而是继承MyBaseMapper
 */
@Mapper
public interface UserMapper extends MyBaseMapper<UserDO> {
    
    

}

4、测试

package com.example.demo;

import com.example.demo.entity.UserDO;
import com.example.demo.mapper.UserMapper;
import org.assertj.core.util.Lists;
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.SpringRunner;

import java.util.ArrayList;
import java.util.List;

@SpringBootTest
@RunWith(SpringRunner.class)
public class SqlInjectorTest {
    
    

    @Autowired
    private UserMapper mapper;

    @Test
    public void updateById() {
    
    
        UserDO user = new UserDO();
        user.setUsername("小小");
        user.setPhone(null);
        user.setSex("女");
        user.setId(1);

        mapper.updateById(user);
        // UPDATE tb_user SET username=?, sex=?, update_time=? WHERE id=?
    }

    @Test
    public void alwaysUpdateSomeColumnById() {
    
    
        UserDO user = new UserDO();
        user.setUsername("小小");
        user.setPhone(null);
        user.setSex("女");
        user.setId(1);

        mapper.alwaysUpdateSomeColumnById(user);
        // UPDATE tb_user SET username=?, phone=?, sex=?, update_time=? WHERE id=?
    }

    @Test
    public void insertBatchSomeColumn() {
    
    
        UserDO user = new UserDO();
        user.setUsername("张三");
        user.setPhone("13811111111");
        user.setSex("女");

        UserDO user1 = new UserDO();
        user1.setUsername("李四");
        user1.setPhone("13822222222");
        user1.setSex(null);

        ArrayList<UserDO> userDOS = Lists.newArrayList(user, user1);
        mapper.insertBatchSomeColumn(userDOS);
        // INSERT INTO tb_user (username,phone,sex,create_time,update_time,deleted) VALUES (?,?,?,?,?,?) , (?,?,?,?,?,?)
    }
}

自定义SQL注入器

1、编写FindAll SQL注入器

package com.example.demo.mybatisplus.methods;

import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlSource;

/**
 * 编写FindAll SQL注入器
 */
public class FindAll extends AbstractMethod {
    
    

    public FindAll() {
    
    
        super("findAll");
    }


    public FindAll(String methodName) {
    
    
        super(methodName);
    }

    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
    
    
        /* 执行 SQL ，动态 SQL 参考类 SqlMethod */
        String sql = "select *  from " + tableInfo.getTableName();
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        return this.addSelectMappedStatementForTable(mapperClass, sqlSource, tableInfo);
    }
}

2、注册到Spring容器

package com.example.demo.config;

import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.injector.DefaultSqlInjector;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.extension.injector.methods.AlwaysUpdateSomeColumnById;
import com.baomidou.mybatisplus.extension.injector.methods.InsertBatchSomeColumn;
import com.example.demo.mybatisplus.methods.FindAll;
import org.springframework.stereotype.Component;

import java.util.List;

/**
 * SQL注入器全局配置
 */
@Component
public class MySqlInjector extends DefaultSqlInjector {
    
    
    @Override
    public List<AbstractMethod> getMethodList(Class<?> mapperClass, TableInfo tableInfo) {
    
    
        List<AbstractMethod> methodList = super.getMethodList(mapperClass, tableInfo);
        /**
         * 自定义SQL注入器注入
         */
        methodList.add(new FindAll());

        return methodList;
    }
}

3、在MyBaseMapper中添加findAll方法

package com.example.demo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

/**
 * 自定义Mapper
 * @param <T>
 */
public interface MyBaseMapper<T> extends BaseMapper<T> {
    
    
    /**
     *  查询所有用户
     */
    List<T> findAll();
}

4、测试

package com.example.demo;

import com.example.demo.entity.UserDO;
import com.example.demo.mapper.UserMapper;
import org.assertj.core.util.Lists;
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.SpringRunner;

import java.util.ArrayList;
import java.util.List;

@SpringBootTest
@RunWith(SpringRunner.class)
public class SqlInjectorTest {
    
    

    @Autowired
    private UserMapper mapper;

    @Test
    public void findAll() {
    
    
        List<UserDO> userDOS = mapper.findAll();
        // select * from tb_user
    }
}

参考

Mybatis-Plus 自定义SQL注入器，非常实用！

Java：MyBatis-Plus内置SQL注入器的使用和自定义SQL注入器

目录

相关文档

环境准备

使用内置扩展SQL注入器

自定义SQL注入器

参考

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