MyBatisPlus Hot Reload beta

• I haven't tried Mybatis. Currently, there is no update recognition for Xml files. But in theory, it should not be supported, but you can try it.
• SQL printing can be enabled through Printing Execution SQL and Time.

Entity Hot Reload

Identification method

• The class contains the com.baomidou.mybatisplus.annotation.TableName annotation.
• The class or parent class inherits the com.baomidou.mybatisplus.extension.activerecord.Model class.

Expected Results

When the class is modified, the information in the Entity class will be regenerated, such as the mapping relationship of table fields, table name, primary key, etc., which is the same as restarting. Of course, it also supports adding new Entity classes.

Example

Add

Adding a new Entity alone does not make any sense. It is usually used together with adding a Mapper when writing code.

Modify

import com.baomidou.mybatisplus.annotation.TableName;
import org.apache.ibatis.annotations.Mapper;

@TableName("user") 
@TableName("dt_user") 
public class User {
    
    @TableId(type = IdType.AUTO)
    private Long id;
    
    private Long deptId;
    
    private String name; 
    private String userName; 
    
    private Integer age; 
    
    private Integer sex; 
}

@Mapper
public interface UserDao extends BaseMapper<User> {
    
    default List<User> getByDeptId(Long deptId) {
        LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<>();
        wrapper.eq(User::getDeptId, deptId);
        return selectList(wrapper);
    }
}

• When we execute userDao.selectList(), it will output select id, deptId, name, sex from user before, and it will output select id, deptId, user_name, age from dt_user after reloading.
• When we execute userDao.getByDeptId(1L), it will output select id, deptId, name, sex from user where dept_id = 1 before, and it will output select id, deptId, user_name, age from dt_user where dept_id = 1 after reloading.

If an Entity object is referenced by two Mappers, both Mappers will update the corresponding Entity class information when they are executed.

@Mapper
public interface User1Dao extends BaseMapper<User> {

}

@Mapper
public interface User2Dao extends BaseMapper<User> {

}

Changes to Entity information will not update the hard-coded information in Mapper. For example, the following getAll method will output select id, deptId, name, sex from user regardless of how User is updated.

@Mapper
public interface UserDao extends BaseMapper<User> {
    
    @Select("select id, deptId, name, sex from user") 
    List<User> getAll(); 
}

Mapper Hot Reload

Identification method

All files under the package path annotated with @MapperScan are read.

• Must be an interface and must contain the org.apache.ibatis.annotations.Mapper annotation
• The class or parent class inherits the com.baomidou.mybatisplus.core.mapper.BaseMapper interface.

TIP

Because the bytecode injection is modified at startup, it currently does not support reading the variable content configured by @MapperScan. Please write the real package path.

Effective configurations such as: @MapperScan("io.github.future0923.test.dao") @MapperScan("io.github.future0923.test..dao") @MapperScan("io.github.future0923.test.") @MapperScan({"io.github.future0923.test.user..dao", "io.github.future0923.test.order..dao"})

Unsupported configurations such as: @MapperScan("${mybatis-plus.mapperPackage}")

Expected Results

The addition and modification of the Mapper interface will regenerate the information in the Mapper interface, including default methods, annotation methods, etc. The proxy class will be regenerated and injected into the Spring Bean, which has the same effect as restarting. Of course, adding new Mapper classes is also supported.

Example

Add

Add entity file。

import com.baomidou.mybatisplus.annotation.TableName;

@TableName("user")
public class User {
    
    @TableId(type = IdType.AUTO)
    private Long id;

    private Long deptId;
    
    private String userName;

    private Integer age;
}

Add mapper file。

import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserDao extends BaseMapper<User> {

    @Select("select user_name, count(1) from user group by user_name")
    Map<String, Integer> getUserCountByName();

    default List<User> getByUserName(String userName) {
        LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(User::getUserName, userName);
        return selectList(wrapper);
    }
}

Add a new Service file to use the UserDao interface.

@Service
public class UserService {
    
    private final UserDao userDao;
    
    public UserService(UserDao userDao) {
        this.userDao = userDao;
    }

    public Map<String, Integer> getUserCountByName() {
        return userDao.getUserCountByName();
    }

    public List<User> getByUserName(String userName) {
        return userDao.getByUserName(userName);
    }
}

After hot reloading, we can call the newly added methods of UserDao and UserService through call method function and they can be executed normally.

Modify

import com.baomidou.mybatisplus.annotation.TableName;
import org.apache.ibatis.annotations.Mapper;

@TableName("user")
public class User {
    
    @TableId(type = IdType.AUTO)
    private Long id;
    
    private Long deptId;
    
    private String userName;
    
    private Integer age;
    
}

@Mapper
public interface UserDao extends BaseMapper<User> {

    @Select("select id, dept_id, name, sex from user") 
    List<User> getAll(); 
    
    default List<User> getByDeptId(Long deptId) { 
        LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<>(); 
        wrapper.eq(User::getDeptId, deptId); 
        return selectList(wrapper); 
    } 
    
    @Select("select user_name, count(1) from user group by user_name") 
    Map<String, Integer> getUserCountByName();  
    @Select("select sex, count(1) from user group by sex") 
    Map<String, Integer> getUserCountBySex();  

    default List<User> getByUserName(String userName) { 
    default List<User> getBySex(Integer sex) { 
        LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(User::getUserName, userName); 
        wrapper.eq(User::getSex, sex); 
        return selectList(wrapper);
    }
    
}

• You can execute the newly added getAll() method, and output select id, dept_id, user_name, sex from user.
• You can execute the newly added getByDeptId(1L) method, and output select id, dept_id, user_name, age from user where dept_id = 1.
• The previous getUserCountByName() method no longer exists. You can execute the modified getUserCountBySex() method, and output select sex, count(1) from user group by sex.
• The previous getByUserName(String userName) method no longer exists. You can execute the modified getBySex(Integer sex) method, and output select id, dept_id, user_name, age from user where sex = xxx.

Xml hot reload

Identification method

Get changes to xml resource files (new/modified)

• New: xml files verified by MyBatis
• Modified: xml resources existing in loadedResources in Configuration

Hot reload function

Recompile the xml file and reload it into Configuration to make the xml effective.

Example

New example

mapper

import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserDao extends BaseMapper<User> {

    Integer getCountByName(@Param("name") String name); 
}

add xml file

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="UserDao">
    <select id="getCountByName" resultType="java.lang.Integer">
        select count(1) from dp_user where name = #{name}
    </select>
</mapper>

Modify example

import org.apache.ibatis.annotations.Mapper;

public class User {
    
    private Long id;
    
    private Long deptId;
    
    private String userName;
    
    private Integer age;
    
}

@Mapper
public interface UserDao extends BaseMapper<User> {

    List<User> selectByNameAndAge(@Param("name") String name, @Param("age") Integer age); 

    Integer selectCount(@Param("name") String name); 
    Long selectCount(@Param("name") String name, @Param("age") Integer age); 
}

modify the xml file

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="UserDao">
    <select id="selectByNameAndAge" resultType="User">
        select * from dp_user where name = #{name} and age = #{age}
    </select>

    <select id="selectCount" resultType="java.lang.Integer">
        select * from dp_user where name = #{name}
    <select id="selectCount" resultType="java.lang.Long">
        select * from dp_user where name = #{name} and age = #{age}
    </select>
</mapper>

After hot reloading, we can call the modified methods of UserDao through call method function and they can be executed normally.