1 条件构造器

通过条件构造器可以更加轻松的完成条件查询与更新(底层就是动态SQL)

1.1 > < =

1. ge 小于 <
   • 例: lt("age", 18)—>age < 18
2. gt 大于 >
   • 例: gt("age", 18)—>age > 18
3. eq 等于 =
   • 例: eq("name", "老王")—>name = '老王'

@Test
public void test1(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();//查询年龄大于24岁用户,姓名为tomqueryWrapper.ge("age",24).eq("name","tom");List<User> userList = userMapper.selectList(queryWrapper);userList.forEach(System.out::println);
}

1.2 in notin

1. in

   in(R column, Collection<?> value)
   in(boolean condition, R column, Collection<?> value)
   

   • 字段 IN (value.get(0), value.get(1), …)
     • 例: in("age",{1,2,3})—>age in (1,2,3)

   in(R column, Object... values)
   in(boolean condition, R column, Object... values)
   

   • 字段 IN (v0, v1, …)
     • 例: in("age", 1, 2, 3)—>age in (1,2,3)

2. notIn

   otIn(R column, Collection<?> value)
   notIn(boolean condition, R column, Collection<?> value)
   

   • 字段 NOT IN (value.get(0), value.get(1), …)
     • 例: notIn("age",{1,2,3})—>age not in (1,2,3)

   notIn(R column, Object... values)
   notIn(boolean condition, R column, Object... values)
   

   • 字段 NOT IN (v0, v1, …)
     • 例: notIn("age", 1, 2, 3)—>age not in (1,2,3)

@Test
public void test2(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();//查询id为1,3,5queryWrapper.in("id",1,3,5);List<User> userList = userMapper.selectList(queryWrapper);userList.forEach(System.out::println);
}

1.3 between…

1. between

   between(R column, Object val1, Object val2)
   between(boolean condition, R column, Object val1, Object val2)
   

   • BETWEEN 值1 AND 值2
     • 例: between("age", 18, 30)—>age between 18 and 30

2. notBetween

   notBetween(R column, Object val1, Object val2)
   notBetween(boolean condition, R column, Object val1, Object val2)
   

   • NOT BETWEEN 值1 AND 值2
     • 例: notBetween("age", 18, 30)—>age not between 18 and 30

@Test
public void test3(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();//查询年龄在20~28之间queryWrapper.between("age",20,28);List<User> userList = userMapper.selectList(queryWrapper);userList.forEach(System.out::println);
}

1.4 orderBy…

1. orderByAsc

   orderByAsc(R... columns)
   orderByAsc(boolean condition, R... columns)
   

   • 排序：ORDER BY 字段, … ASC
     • 例: orderByAsc("id", "name")—>order by id ASC,name ASC

2. orderByDesc

   orderByDesc(R... columns)
   orderByDesc(boolean condition, R... columns)
   

   • 排序：ORDER BY 字段, … DESC
     • 例: orderByDesc("id", "name")—>order by id DESC,name DESC

3. orderBy

   orderBy(boolean condition, boolean isAsc, R... columns)
   

   • 排序：ORDER BY 字段, …
   • 例: orderBy(true, true, "id", "name")—>order by id ASC,name ASC

@Test
public void test4(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();//查询按照年龄降序，如果年龄相等按照姓名降序queryWrapper.orderByDesc("age","name");List<User> userList = userMapper.selectList(queryWrapper);userList.forEach(System.out::println);
}

@Test
public void test5(){QueryWrapper<User> queryWrapper = new QueryWrapper<>();//查询姓名中包含%S%//queryWrapper.like("name","s");//查询姓名中包含%S//queryWrapper.likeLeft("name","s");//查询姓名中包含S%queryWrapper.likeRight("name","s");List<User> userList = userMapper.selectList(queryWrapper);userList.forEach(System.out::println);
}

1.5 like…

1. like

   like(R column, Object val)
   like(boolean condition, R column, Object val)
   

   • LIKE ‘%值%’
     • 例: like("name", "王")—>name like '%王%'

2. notLike

   notLike(R column, Object val)
   notLike(boolean condition, R column, Object val)
   

   • NOT LIKE ‘%值%’
     • 例: notLike("name", "王")—>name not like '%王%'

3. likeLeft

   likeLeft(R column, Object val)
   likeLeft(boolean condition, R column, Object val)
   

   • LIKE ‘%值’
     • 例: likeLeft("name", "王")—>name like '%王'

4. likeRight

   likeRight(R column, Object val)
   likeRight(boolean condition, R column, Object val)
   

   • LIKE ‘值%’
     • 例: likeRight("name", "王")—>name like '王%'

5. notLikeLeft

   notLikeLeft(R column, Object val)
   notLikeLeft(boolean condition, R column, Object val)
   

   • NOT LIKE ‘%值’
     • 例: notLikeLeft("name", "王")—>name not like '%王'

6. notLikeRight

   notLikeRight(R column, Object val)
   notLikeRight(boolean condition, R column, Object val)
   

   • NOT LIKE ‘值%’
     • 例: notLikeRight("name", "王")—>name not like '王%'

7. isNull

   isNull(R column)
   isNull(boolean condition, R column)
   

   • 字段 IS NULL
     • 例: isNull("name")—>name is null

8. isNotNull

   isNotNull(R column)
   isNotNull(boolean condition, R column)
   

   • 字段 IS NOT NULL
     • 例: isNotNull("name")—>name is not null

@Test
public void test6(){UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();//修改姓名中不包含s的用户updateWrapper.notLike("name","s");User user = new User();user.setName("尼古拉斯");userMapper.update(user,updateWrapper);
}

2 代码生成器

AutoGenerator 是 MyBatis-Plus 的代码生成器，通过 AutoGenerator 可以快速生成 Entity、Mapper、Mapper XML、Service、Controller 等各个模块的代码，极大的提升了开发效率。

2.1 引入依赖

• 代码生成器依赖
• 模板引擎 依赖
• 日志依赖

<!--  代码生成器依赖  -->
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-generator</artifactId><version>3.4.1</version>
</dependency>
<!--  模板引擎 依赖  -->
<dependency><groupId>org.apache.velocity</groupId><artifactId>velocity-engine-core</artifactId><version>2.3</version>
</dependency>
<!--   日志依赖     -->
<dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>1.7.30</version>
</dependency>

2.2 生成器代码

1. 代码生成器相关诶之
2. 数据源配置
3. 包配置
4. 策略配置
5. 其他配置

public class CodeGenerator {public static void main(String[] args) {// 代码生成器AutoGenerator mpg = new AutoGenerator();// 全局配置GlobalConfig gc = new GlobalConfig();//获取当前路径String projectPath = System.getProperty("user.dir");//设置生成代码位置gc.setOutputDir(projectPath + "/src/main/java");//设置代码文件头作者gc.setAuthor("ying");//设置是否在资源管理器打开gc.setOpen(false);//设置生成代码是否覆盖gc.setFileOverride(true);//设置去除生成代码接口中的Igc.setServiceName("%sService");mpg.setGlobalConfig(gc);// 数据源配置DataSourceConfig dsc = new DataSourceConfig();dsc.setUrl("jdbc:mysql:///java11");dsc.setDriverName("com.mysql.jdbc.Driver");dsc.setUsername("root");dsc.setPassword("123456");mpg.setDataSource(dsc);// 包配置PackageConfig pc = new PackageConfig();//设置模块名称//pc.setModuleName("shopping");pc.setParent("com.ying");pc.setEntity("pojo");pc.setMapper("mapper");pc.setService("service");pc.setController("controller");mpg.setPackageInfo(pc);// 策略配置StrategyConfig strategy = new StrategyConfig();//表名  下划线转驼峰strategy.setNaming(NamingStrategy.underline_to_camel);//字段名  下划线转驼峰strategy.setColumnNaming(NamingStrategy.underline_to_camel);//实体类是否使用lombokstrategy.setEntityLombokModel(true);//Controller是否使用RESTful风格(RestController)strategy.setRestControllerStyle(true);//设置逻辑删除字段(数据库中需要有deleted字段)strategy.setLogicDeleteFieldName("deleted");//设置乐观锁注解(数据库中需要有version字段)strategy.setVersionFieldName("version");//设置生成的表名strategy.setInclude("user");mpg.setStrategy(strategy);mpg.execute();}
}