标签：column 开发 Result import Mybatis 注解 property id user
开头
注解开发的主配置文件仍旧与之前相同，注解开发是面向于dao的。
某个dao只能使用注解开发，或配置文件中的一种，不能同时使用
但可以ADao使用注解开发，BDao使用配置文件开发
一、简单的增删改查
package com.czy.dao;
import com.czy.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import java.util.List;
public interface UserDao {
/**
* 查询所有用户
* @return
*/
@Select("select * from user")
List<User> findAll();
/**
* 保存用户
* @param user
*/
@Insert("insert into user(username,address,sex,birthday) values(#{username},#{address},#{sex},#{birthday})")
void saveUser(User user);
@Update("update user set username = #{username},address = #{address},sex = #{sex},birthday = #{birthday} where id = #{id}")
void updateUser(User user);
@Delete("delete from user where id = #{id}")
void deleteUser(Integer userId);
@Select("select * from user where id = #{id}")
User findById(Integer id);
@Select("select * from user where username like '%${value}%'")
List<User> findUserByName(String name);
@Select("select count(*) from user")
int findTotalUser();
}
二、注解实现复杂关系映射开发
1、属性和数据库列不对应关系（ResultMap）
/**
* 查询所有用户
* @return
*/
@Select("select * from user")
@Results(value= {
@Result(id=true ,column = "id", property = "userId"),
@Result(column = "username", property = "userName"),
@Result(column = "address", property = "userAddress"),
@Result(column = "sex", property = "userSex"),
@Result(column = "birthday", property = "userBirthday")
},id="userMap"
)
List<User> findAll();
@Select("select * from user where id = #{id}")
@ResultMap({"userMap"})
User findById(Integer id);
Results注解源码
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.apache.ibatis.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface Results {
String id() default "";
Result[] value() default {};
}
Result注解源码
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.apache.ibatis.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.UnknownTypeHandler;
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({})
public @interface Result {
boolean id() default false;
String column() default "";
String property() default "";
Class<?> javaType() default void.class;
JdbcType jdbcType() default JdbcType.UNDEFINED;
Class<? extends TypeHandler> typeHandler() default UnknownTypeHandler.class;
One one() default @One;
Many many() default @Many;
}
ResultMap注解源码
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.apache.ibatis.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface ResultMap {
String[] value();
}
2、多表查询
一个用户可以有多个账户，每个账户对应单个用户
多对一（mybatis中的一对一）
自我实现
/**
* 查询所有账户并获取其所属的用户信息
* @return
*/
@Select("select user.*, a.id aid, a.uid uid,a.money money from account a,user where a.uid = user.id")
@Results(id = "accountMap",value = {
@Result(id = true,column = "aid",property = "id"),
@Result(column = "uid",property = "uid"),
@Result(column = "money",property = "money"),
@Result(column = "id",property = "user.userId"),
@Result(column = "username",property = "user.userName"),
@Result(column = "address",property = "user.userAddress"),
@Result(column = "sex",property = "user.userSex"),
@Result(column = "birthday",property = "user.userBirthday")
})
List<Account> findAll();
mybatis封装实现
/**
* 查询所有账户并获取其所属的用户信息
* @return
*/
@Select("select * from account")
@Results(id = "accountMap",value = {
@Result(id = true,column = "id",property = "id"),
@Result(column = "uid",property = "uid"),
@Result(column = "money",property = "money"),
@Result(property = "user",column = "uid",one = @One(select = "com.czy.dao.UserDao.findById",fetchType = FetchType.EAGER))
})
List<Account> findAll();
通过one标签实现
one标签源码
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.apache.ibatis.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.apache.ibatis.mapping.FetchType;
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({})
public @interface One {
String select() default "";
FetchType fetchType() default FetchType.DEFAULT;
}
其中的Fetch即为预加载(lazy)和立即加载(eager)的设置
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.apache.ibatis.mapping;
public enum FetchType {
LAZY,
EAGER,
DEFAULT;
private FetchType() {
}
}
一对多
@Select("select * from user")
@Results(value= {
@Result(id=true ,column = "id", property = "userId"),
@Result(column = "username", property = "userName"),
@Result(column = "address", property = "userAddress"),
@Result(column = "sex", property = "userSex"),
@Result(column = "birthday", property = "userBirthday"),
@Result(property = "accounts",column = "id",many = @Many(select = "com.czy.dao.AccountDao.findByUid",fetchType = FetchType.LAZY))
},id="userMap"
)
List<User> findAll();
many源码类似于One
标签：column,开发,Result,import,Mybatis,注解,property,id,user 来源： https://www.cnblogs.com/czy-algorithm/p/16064271.html
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