1.背景
mybatis-plus除了常规的一些CRUD还有其他的的功能如下
2.逻辑删除
2.1.实现配置
步骤一、数据库准备一个逻辑删除字段，一般是deleted
步骤二、配置文件中添加入下配置
步骤三、java实体上加标签如下：
2.2.实际案例演示
package com.ldp.demo01;
import com.ldp.entity.SysUser;
import com.ldp.mapper.SysUserMapper;
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;
/**
* @author 姿势帝-博客园
* @address https://www.cnblogs.com/newAndHui/
* @WeChat 851298348
* @create 12/14 7:13
* @description <p>
* 逻辑删除测试
* </p>
*/
@RunWith(SpringRunner.class)
@SpringBootTest
public class Test11LogicDeleted {
@Autowired
private SysUserMapper sysUserMapper;
/**
* 逻辑删除测试
* <p>
* ==> Preparing: UPDATE sys_user SET deleted=1 WHERE id=? AND deleted=0
* ==> Parameters: 26(Integer)
* <== Updates: 1
* <p>
* 注意观察:虽然我执行的是删除,但是因为配置了逻辑删除,使用最后执行的本质sql是更新,
* 而且在更新的sql语句中还加入了deleted=0这个条件
* 那么试想一想,如果是查询、修改会加入deleted=0这个条件么？
*/
@Test
public void test01() {
int row = sysUserMapper.deleteById(25);
System.out.println("受影响行数:" + row);
}
/**
* 测试逻辑删除下的查询
* <p>
* ==> Preparing: SELECT id,version,age,gender,name,parent_id,position,account,we_chat,password,status,type,create_time,update_time,deleted
* FROM sys_user WHERE id=? AND deleted=0
* ==> Parameters: 25(Integer)
* <p>
* 注意逻辑删除下的查询是加了 AND deleted=0 作为查条件的
*/
@Test
public void test02() {
SysUser sysUser = sysUserMapper.selectById(25);
System.out.println("sysUser=" + sysUser);
}
/**
* 逻辑删除下的更新
* <p>
* ==> Preparing: UPDATE sys_user SET name=? WHERE id=? AND deleted=0
* ==> Parameters: 逻辑删除测试(String), 25(Integer)
* <p>
* 注意从sql语句上看也是添加了deleted=0的
*/
@Test
public void test03() {
int row = sysUserMapper.updateById(new SysUser().setId(25).setName("逻辑删除测试"));
System.out.println("受影响行数=" + row);
}
/**
* 逻辑删除下的新增
* ==> Preparing: INSERT INTO sys_user ( age, name ) VALUES ( ?, ? )
* ==> Parameters: 18(Integer), 新增测试(String)
* <== Updates: 1
* 注意从sql语句来看，在添加的时候并没有帮我们自动添加deleted=0字段的值，
* 所有在实际生产中最佳的作法是在数据库设置默认值为0
*/
@Test
public void test04() {
int row = sysUserMapper.insert(new SysUser().setName("新增测试").setAge(18));
System.out.println("受影响行数=" + row);
}
}
View Code
3.自动填充
第一步：注解填充字段 @TableField(.. fill = FieldFill.INSERT) 生成器策略部分也可以配置！
/**
* 表示创建时自动填充
*/
@TableField(value = "create_time",fill = FieldFill.INSERT)
private Date createTime;
/**
* 表示更新时自动填充
*/
@TableField(fill = FieldFill.UPDATE)
private Date updateTime;
第二步：自定义实现类 MyMetaObjectHandler
package com.ldp.config;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.util.Date;
/**
* @author 姿势帝-博客园
* @address https://www.cnblogs.com/newAndHui/
* @WeChat 851298348
* @create 12/14 8:03
* @description
*/
@Slf4j
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
@Override
public void insertFill(MetaObject metaObject) {
log.info("start insert fill ....");
this.strictInsertFill(metaObject, "createTime", () -> new Date(), Date.class); // 起始版本 3.3.3(推荐)
}
@Override
public void updateFill(MetaObject metaObject) {
log.info("start update fill ....");
this.strictUpdateFill(metaObject, "updateTime", () -> new Date(), Date.class); // 起始版本 3.3.3(推荐)
}
}
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第三步：测试
package com.ldp.demo01;
import com.ldp.entity.SysUser;
import com.ldp.mapper.SysUserMapper;
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;
/**
* @author 姿势帝-博客园
* @address https://www.cnblogs.com/newAndHui/
* @WeChat 851298348
* @create 12/14 8:10
* @description <p>
* 自动填充
* </p>
*/
@RunWith(SpringRunner.class)
@SpringBootTest
public class Test12FieldFill {
@Autowired
private SysUserMapper sysUserMapper;
/**
* 新增时自动填充
* <p>
* ==> Preparing: INSERT INTO sys_user ( age, name, create_time ) VALUES ( ?, ?, ? )
* ==> Parameters: 18(Integer), 自动填充(String), 2020-12-14 19:55:36.065(Timestamp)
* <== Updates: 1
*/
@Test
public void test01() {
int row = sysUserMapper.insert(new SysUser().setName("自动填充").setAge(18));
System.out.println("受影响行数=" + row);
}
/**
* 更新时自动填充
* <p>
* ==> Preparing: UPDATE sys_user SET name=?, update_time=? WHERE id=? AND deleted=0
* ==> Parameters: 更新自动填充(String), 2020-12-14 19:56:16.539(Timestamp), 25(Integer)
* <== Updates: 1
*/
@Test
public void test02() {
int row = sysUserMapper.updateById(new SysUser().setId(25).setName("更新自动填充"));
System.out.println("受影响行数=" + row);
}
}
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4.乐观锁
实现原理：
取出记录时，获取当前version 更新时，带上这个version 执行更新时， set version = newVersion where version = oldVersion 如果version不对，就更新失败
具体实现
第一步：数据库和java实体添加字段version，并在实体上添加注解@Version
/**
* 乐观锁
*/
@Version
private Integer version;
第二步：注册乐观锁插件
package com.ldp.config;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.pagination.optimize.JsqlParserCountOptimize;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* @author 姿势帝-博客园
* @address https://www.cnblogs.com/newAndHui/
* @WeChat 851298348
* @create 12/06 4:45
* @description
*/
@Configuration
public class MybatisPlusConfig {
/**
* 乐观锁配置
*
* @return
*/
@Bean
public MybatisPlusInterceptor optimisticLockerInnerInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
interceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
return interceptor;
}
@Bean
public PaginationInterceptor paginationInterceptor() {
PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
// 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求 默认false
// paginationInterceptor.setOverflow(false);
// 设置最大单页限制数量，默认 500 条，-1 不受限制
// paginationInterceptor.setLimit(500);
// 开启 count 的 join 优化,只针对部分 left join
paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
return paginationInterceptor;
}
}
View Code
第三步：测试
package com.ldp.demo01;
import com.ldp.entity.SysUser;
import com.ldp.mapper.SysUserMapper;
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;
/**
* @author 姿势帝-博客园
* @address https://www.cnblogs.com/newAndHui/
* @WeChat 851298348
* @create 12/14 9:40
* @description
*/
@RunWith(SpringRunner.class)
@SpringBootTest
public class Test13Version {
@Autowired
private SysUserMapper sysUserMapper;
/**
* 乐观锁测试
* ==> Preparing: UPDATE sys_user SET version=?, name=?, update_time=? WHERE id=? AND version=? AND deleted=0
* ==> Parameters: 8(Integer), 乐观锁测试(String), 2020-12-14 22:04:15.04(Timestamp), 12(Integer), 7(Integer)
* <== Updates: 1
* 注意观察sql,查询出来的version=7,在更新的时候将session版本设置为8
*/
@Test
public void test01() {
SysUser sysUser = sysUserMapper.selectById(12);
int row = sysUserMapper.updateById(
new SysUser()
.setId(sysUser.getId())
.setName("乐观锁测试")
.setVersion(sysUser.getVersion())
);
System.out.println("受影响行数=" + row);
}
}
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