插件机制
自动填充
项目中经常会遇到一些数据,每次都使用相同的方式填充,例如记录的创建时间,更新时间等。
我们可以使用MyBatis Plus的自动填充功能,完成这些字段的赋值工作
原理
alter table tmp_customer add column create_time date;
alter table tmp_customer add column update_time date;
步骤二:修改JavaBean
package com.czxy.mp.domain;
import com.baomidou.mybatisplus.annotation.*;
import lombok.Data;
import java.util.Date;
@Data
@TableName("tmp_customer")
public class Customer {
@TableId(type = IdType.AUTO)
private Integer cid;
private String cname;
private String password;
private String telephone;
private String money;
@TableField(value="create_time",fill = FieldFill.INSERT)
private Date createTime;
@TableField(value="update_time",fill = FieldFill.UPDATE)
private Date updateTime;
}
步骤三:编写处理类
package com.czxy.mp.handler;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.util.Date;
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
@Override
public void insertFill(MetaObject metaObject) {
this.setFieldValByName("createTime", new Date(), metaObject);
}
@Override
public void updateFill(MetaObject metaObject) {
this.setFieldValByName("updateTime", new Date(), metaObject);
}
}
步骤四:测试
@Test
public void testInsert() {
Customer customer = new Customer();
customer.setCname("测试888");
customerMapper.insert(customer);
}
@Test
public void testUpdate() {
Customer customer = new Customer();
customer.setCid(11);
customer.setTelephone("999");
customerMapper.updateById(customer);
}
乐观锁
实现
步骤一:修改表结构,添加version字段
步骤二:修改JavaBean,添加version属性
package com.czxy.mp.config;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.util.Date;
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
@Override
public void insertFill(MetaObject metaObject) {
this.setFieldValByName("createTime", new Date(), metaObject);
this.setFieldValByName("version", 1, metaObject);
}
@Override
public void updateFill(MetaObject metaObject) {
this.setFieldValByName("updateTime", new Date(), metaObject);
}
}
步骤四:修改 MybatisPlusConfig 开启乐观锁
package com.czxy.mp.config;
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MybatisPlusConfig {
*/
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor(){
MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
mybatisPlusInterceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
return mybatisPlusInterceptor;
}
}
步骤五:测试
@Test
public void testUpdate() {
Customer customer = new Customer();
customer.setCid(14);
customer.setCname("测试999");
customer.setVersion(1);
int i = customerMapper.updateById(customer);
System.out.println(i);
}
注意事项:
- 支持的数据类型只有:int,Integer,long,Long,Date,Timestamp,LocalDateTime
- 整数类型下 newVersion = oldVersion + 1
- newVersion 会回写到 entity 中
- 仅支持 updateById(id) 与 update(entity, wrapper) 方法
- 在 update(entity, wrapper) 方法下, wrapper 不能复用!!!
逻辑删除
逻辑删除,也称为删除。就是在表中提供一个字段用于记录是否删除,实际该数据没有被删除
实现
步骤一:修改表结构添加deleted字段
步骤二:修改JavaBean,给deleted字段添加@TableLogic
package com.czxy.mp.config;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.util.Date;
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
@Override
public void insertFill(MetaObject metaObject) {
this.setFieldValByName("createTime", new Date(), metaObject);
this.setFieldValByName("version", 1, metaObject);
this.setFieldValByName("deleted", 0, metaObject);
}
@Override
public void updateFill(MetaObject metaObject) {
this.setFieldValByName("updateTime", new Date(), metaObject);
}
}
步骤四:测试
@Test
public void testDelete() {
int i = customerMapper.deleteById(12);
System.out.println(i);
}
全局配置
如果使用了全局配置,可以不使用注解@TableLogic
mybatis-plus:
global-config:
db-config:
logic-delete-field: deleted # 局逻辑删除的实体字段名
logic-delete-value: 1 # 逻辑已删除值(默认为 1)
logic-not-delete-value: 0 # 逻辑未删除值(默认为 0)
通用Service
标准service:接口 + 实现
service接口
package com.czxy.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.czxy.domain.Customer;
public interface CustomerService extends IService<Customer> {
}
service实现类
package com.czxy.service.impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.czxy.domain.Customer;
import com.czxy.mapper.CustomerMapper;
import com.czxy.service.CustomerService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
@Service
@Transactional
public class CustomerServiceImpl extends ServiceImpl<CustomerMapper,Customer> implements CustomerService {
}
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