作者 | Asong臭狗屎
来源 | cnblogs.com/chougoushi/p/13451800.html
1、性能分析插件
我们在平时的开发中,会遇到一些慢sql,测试,druid
MP(MyBatisPlus)也提供性能分析插件,如果超过这个时间就停止
不过官方在3.2版本的时候取消了,原因如下
2、条件构造器
十分重要: Wrapper我们写一些复杂查询的时候
（1）首先创建一个测试类
@SpringBootTest
public class MyBatisPlusWrapperTest {
@Autowired
private AirMapper airMapper;
}实体类
@Data
@EqualsAndHashCode(callSuper = false)
public class Air implements Serializable {
private static final long serialVersionUID=1L;
@TableId(value = "id", type = IdType.AUTO)
private Long id;
private Integer districtId;
@TableField(fill = FieldFill.INSERT)
private Date monitorTime;
private Integer pm10;
private Integer pm25;
private String monitoringStation;
@TableField(fill = FieldFill.INSERT)
private Date lastModifyTime;
@Version
private Integer version;
@TableLogic
private Integer deleted;
}建表语句(.sql文件)
/*
Navicat Premium Data Transfer
Source Server : wpsPractice1
Source Server Type : MySQL
Source Server Version : 80020
Source Host : localhost:3306
Source Schema : air
Target Server Type : MySQL
Target Server Version : 80020
File Encoding : 65001
Date: 07/08/2020 11:44:27
*/
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for air
-- ----------------------------
DROP TABLE IF EXISTS `air`;
CREATE TABLE `air` (
`id` bigint unsigned NOT NULL,
`district_id` int(0) NULL DEFAULT NULL,
`monitor_time` datetime(0) NULL DEFAULT NULL,
`pm10` int(0) NULL DEFAULT NULL,
`pm25` int(0) NULL DEFAULT NULL,
`monitoring_station` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`last_modify_time` datetime(0) NULL DEFAULT NULL,
`version` int(0) NOT NULL DEFAULT 1,
`deleted` int(0) NOT NULL DEFAULT 0,
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of air
-- ----------------------------
INSERT INTO `air` VALUES (4, 4, '2020-06-04 00:00:00', 22, 23, '哈哈哈哈站', '2020-07-15 00:00:00', 1, 1);
INSERT INTO `air` VALUES (5, 5, '2020-06-04 00:00:00', 22, 23, '哈哈哈哈站', '2020-07-15 00:00:00', 1, 0);
INSERT INTO `air` VALUES (6, 6, '2020-06-04 00:00:00', 22, 23, '哈哈哈哈站', '2020-07-15 00:00:00', 1, 0);
INSERT INTO `air` VALUES (7, 7, '2020-06-04 00:00:00', 22, 23, '休息休息站', '2020-08-19 00:00:00', 1, 0);
INSERT INTO `air` VALUES (8, 8, '2020-08-20 00:00:00', 33, 44, '嘎嘎嘎嘎站', '2020-08-27 00:00:00', 1, 0);
INSERT INTO `air` VALUES (9, 4, '2020-08-05 03:56:49', 33, 65, '哈马屁', '2020-08-05 03:56:49', 1, 0);
INSERT INTO `air` VALUES (11, 11, '2020-08-05 03:51:08', 33, 65, '哈哈哈哈哈哈', '2020-08-05 03:51:08', 1, 0);
INSERT INTO `air` VALUES (222, 11, '2020-08-06 15:57:42', 33, 44, '快乐', '2020-08-19 15:57:59', 1, 0);
INSERT INTO `air` VALUES (1290858950387945474, 11, '2020-08-05 03:55:31', 33, 65, '哈哈哈哈哈哈', '2020-08-05 03:55:31', 1, 0);
SET FOREIGN_KEY_CHECKS = 1;// 查询一些用户:
// 查询一下pm10为22且monitoring_station不为空的用户,
@Test
public void test1(){
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.isNotNull("monitoring_station")//数据库中的名字,而不是实体类中的名字
.eq("pm10",22);
List<Air> airList = airMapper.selectList(wrapper);//可以对比下map的查询
airList.forEach(System.out::println);//循环遍历输出
}
//查询单个用户
@Test
public void test2() {
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.eq("id",222);
airMapper.selectOne(wrapper);
}
//Butween And
//查询pm25在40-60之间的用户和数量
@Test
public void test3() {
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.between("pm25",40,60);//区间
airMapper.selectList(wrapper).forEach(System.out::println);
System.out.println(airMapper.selectCount(wrapper));//查询结果数
}
//模糊查询
//查询monitor_station中带"站"的,切不带"哈"的
@Test
public void test4() {
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.like("monitoring_station","站").notLike("monitoring_station","哈");
airMapper.selectList(wrapper).forEach(System.out::println);
}
//查询以哈开头切以站结尾的 哈% %站
@Test
public void test5() {
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.likeLeft("monitoring_station","站").likeRight("monitoring_station","哈");
airMapper.selectList(wrapper).forEach(System.out::println);
}
//嵌入sql查询
@Test
public void test6() {
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.inSql("district_id","select id from air where district_id = id");
airMapper.selectObjs(wrapper).forEach(System.out::println);
}
//多表查询
//通过id进行排序
@Test
public void test7() {
QueryWrapper<Air> wrapper = new QueryWrapper<>();
wrapper.orderByDesc("id");
airMapper.selectList(wrapper).forEach(System.out::println);
}3、代码生成器
（1）导入依赖
在3.0.3版本以后代码生成器需要手动添加依赖
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-generator</artifactId>
<version>3.3.2</version>
</dependency>根据前端的模板引擎导入相应依赖(我没写前端页面就随便导入了一个velocity的)记住一定要加入其中一个,否则会报错
package com.cloudcentury.mybatis;
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.config.DataSourceConfig;
import com.baomidou.mybatisplus.generator.config.GlobalConfig;
import com.baomidou.mybatisplus.generator.config.PackageConfig;
import com.baomidou.mybatisplus.generator.config.StrategyConfig;
import com.baomidou.mybatisplus.generator.config.po.TableFill;
import com.baomidou.mybatisplus.generator.config.rules.DateType;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;
import java.util.ArrayList;
/**
* ClassName:臭狗屎
* Package:com.cloudcentury.mybatis
*
* @date:2020/8/7 10:22
* @author:2628710400@qq.com Description:
*/
public class CodeAuto {
public static void main(String[] args) {
//需要构建一个代码自动生成器对象
AutoGenerator ag = new AutoGenerator();//代码生辰器对象
//配置执行策略
//1.全局配置
GlobalConfig gc = new GlobalConfig();//全局配置对象
String property = System.getProperty("user.dir");//获取项目名称
System.out.println(property);
gc.setOutputDir(property+"/src/main/java");//设置代码存放路径
gc.setAuthor("臭狗屎");//设置作者
gc.setOpen(false);//设置是否打开资源管理器(生成完毕后)
gc.setFileOverride(false);//是否覆盖代码
gc.setServiceName("%sService");//去掉Service的I前缀
gc.setIdType(IdType.AUTO);//设置id自动生成类型
gc.setDateType(DateType.ONLY_DATE);//日期时间,仅仅时间
gc.setSwagger2(false);//是否设置swagger
ag.setGlobalConfig(gc);//将全局配置放到里面
//设置数据源
DataSourceConfig desc = new DataSourceConfig();//数据源配置对象
//设置url
desc.setUrl("jdbc:mysql://localhost:3306/air?characterEncoding=utf8&serverTimezone=GMT");
desc.setDriverName("com.mysql.cj.jdbc.Driver");//设置驱动
desc.setUsername("root");//设置用户名
desc.setPassword("12345");//设置密码
desc.setDbType(DbType.MYSQL);//设置数据库类型
ag.setDataSource(desc);//将数据源放到里面
//包的配置
//说白了就是说需要生成那些包,叫什么
PackageConfig pc = new PackageConfig();//包配置对象
pc.setModuleName("com");//模块名字
pc.setParent("com.cloudcentury");//父模块名字
pc.setEntity("entity");//Entity包的名字
pc.setMapper("mapper");//mapper包的名字
pc.setService("service");//service包的名字
pc.setController("controller");//controller包的名字
ag.setPackageInfo(pc);//将包的配置放到里面
//策略配置
StrategyConfig sc = new StrategyConfig();
sc.setInclude("air","district"); //设置要映射的表名,这个一定要设置的
sc.setNaming(NamingStrategy.underline_to_camel);//设置名字下划线转大写
sc.setColumnNaming(NamingStrategy.underline_to_camel);//设置列明下划线转大写
sc.setEntityLombokModel(true);//自动生成lombok
sc.setLogicDeleteFieldName("deleted");//逻辑删除的名字
//自动填充配置
TableFill monitor_time = new TableFill("monitor_time", FieldFill.INSERT);//执行插入是更新时间
TableFill last_modify_time = new TableFill("last_modify_time", FieldFill.INSERT);//执行更新时执行的操作
ArrayList<TableFill> tableFills = new ArrayList<>();//创建一个List
tableFills.add(monitor_time);
tableFills.add(last_modify_time);
sc.setTableFillList(tableFills);//这里只有这一个用list的方法
sc.setVersionFieldName("version"); //乐观锁的配置
sc.setRestControllerStyle(true);//开启rest式的驼峰命名
sc.setControllerMappingHyphenStyle(true);//下划线命名:localhost:8080/hello_id_2
ag.setStrategy(sc);//策略配置对象
ag.execute();//执行
}
}