Mybatis個人筆記

Mybatis官方文檔：

https://mybatis.org/mybatis-3/zh/index.html

1. 為什麼需要MyBatis

幫助程式員将資料存入到資料庫中
友善
傳統的JDBC代碼太複雜了，簡化，架構，自動化
不用MyBatis也可以，技術沒有高低之分
優點：
- 簡單易學
- 靈活
- sql和代碼的分離，提高了可維護性。
- 提供映射标簽，支援對象與資料庫的orm字段關系映射
- 提供對象關系映射标簽，支援對象關系組建維護
- 提供xml标簽，支援編寫動态sql

2、第一個Mybatis程式

思路：搭建環境 --> 導入MyBatis --> 編寫代碼 --> 測試

.2.1導入maven依賴配置

<dependencies>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.5</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.21</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.13</version>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.12</version>
    </dependency>
</dependencies>
<build>
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
    </resources>
</build>

2.2目錄結構

2.3mybatis-config配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--configuration核心配置檔案-->
<configuration>
    <properties resource="db-config.properties"/>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="mapper/UserDao.xml" />
    </mappers>
</configuration>

注意點:這裡url的value需要使用${jdbc.url}否則在編譯的時候回出現錯誤，value值回自動替換成www.example.com

2.4 db-config.properties配置

====

2.5 編寫mybatisUtil工具類

package com.zhangpan.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.apache.ibatis.session.SqlSessionManager;

import java.io.IOException;
import java.io.InputStream;

public class MybatisUtil {

    static SqlSessionFactory sqlSessionFactory = null;

    static {

        try {

            String MybatisConfig = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(MybatisConfig);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static SqlSession getSqlSession(){

        return sqlSessionFactory.openSession();
    }

}

2.6編寫dao接口

package com.zhangpan.mapper;

import com.zhangpan.pojo.User;

import java.util.List;

public interface UserDao {

    public List<User> getUserList();

    public void addUser(User user);
}

2.7編寫接口實作UserDao.xml(由原來的接口實作類變成xml配置檔案)

<?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">

<!--namespace=綁定一個指定的Dao/Mapper接口-->
<mapper namespace="com.zhangpan.mapper.UserDao">
    <select id="getUserList" resultType="com.zhangpan.pojo.User">
    select * from USER
  </select>

    <select id="addUser" parameterType="com.zhangpan.pojo.User">
        insert into USER (username,sex,birthday,address) value (#{username},#{sex},#{birthday},#{address})
    </select>
</mapper>

2.8 Junit測試

package com.zhangpan;

import com.zhangpan.mapper.UserDao;
import com.zhangpan.pojo.User;
import com.zhangpan.utils.MybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.Date;
import java.util.List;

public class test {


    @Test
    public void test1(){

        SqlSession sqlSession = MybatisUtil.getSqlSession();

        UserDao userDao = sqlSession.getMapper(UserDao.class);

        List<User> userList = userDao.getUserList();
        for (User user:userList){

            System.out.println(user);
        }

        sqlSession.close();
    }


    @Test
    public void addUser_test(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();

        UserDao userDao = sqlSession.getMapper(UserDao.class);

        User user = new User();

        user.setUsername("關二爺");
        user.setSex("1");
        user.setBirthday(new Date());
        user.setAddress("光棍屯18号");

        userDao.addUser(user);

        sqlSession.commit();
        sqlSession.close();

    }
}

3、通過配置檔案實作CURD

1. namespace**

namespace中的包名要和Dao/Mapper接口的包名一緻

選擇，查詢語句；

id：就是對應的namespace中的方法名；
resultType : Sql語句執行的傳回值；
parameterType : 參數類型；

import com.zhangpan.pojo.User;
import org.omg.CORBA.PUBLIC_MEMBER;

import java.util.List;
import java.util.Map;

public interface UserDao {

    public List<User> getUserList();

    public void addUser(User user);

    public void addUserMap(Map<String,Object> map);

    public List<User> getUserLike(String username);

    public List<User> getUserByLimit(Map<String,Integer> map);

    public List<User> getUserByRowBounds();
}

userDao.xml檔案

<?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">

<!--namespace=綁定一個指定的Dao/Mapper接口-->

<mapper namespace="com.zhangpan.mapper.UserDao">

    <resultMap id="UserMap" type="User">


        <result column="username" property="username"/>
        <result column="address" property="address"/>

    </resultMap>

    <select id="getUserList" resultType="User">
        select * from USER
     </select>

    <select id="addUser" parameterType="User">
        insert into USER (username,sex,birthday,address) value (#{username},#{sex},#{birthday},#{address})
    </select>

    <select id="addUserMap" parameterType="map">
        insert into USER (username,sex,birthday,address) value (#{username},#{sex},#{birthday},#{address})
    </select>

    <select id="getUserLike" parameterType="String" resultMap="UserMap">
        select * from USER where username like "%"#{username}"%"
    </select>
    
    <select id="getUserByLimit" parameterType="map" resultMap="UserMap">
        select * from user limit #{startIndex},#{pageSize}
    </select>

    <select id="getUserByRowBounds" resultMap="UserMap">
        select * from user
    </select>
</mapper>

測試類

package com.zhangpan;

import com.zhangpan.mapper.UserDao;
import com.zhangpan.pojo.User;
import com.zhangpan.utils.MybatisUtil;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.Test;

import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class test {

    Logger logger = Logger.getLogger(test.class);

    @Test
    public void test1(){

        SqlSession sqlSession = MybatisUtil.getSqlSession();

        UserDao userDao = sqlSession.getMapper(UserDao.class);

        List<User> userList = userDao.getUserList();
        for (User user:userList){

            System.out.println(user);
        }

        sqlSession.close();
    }


    @Test
    public void addUser_test(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();

        UserDao userDao = sqlSession.getMapper(UserDao.class);

        User user = new User();

        user.setUsername("關二爺");
        user.setSex("1");
        user.setBirthday(new Date());
        user.setAddress("光棍屯18号");

        userDao.addUser(user);

        sqlSession.commit();
        sqlSession.close();

    }

    @Test
    public void addUser_map(){

        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);

        HashMap<String,Object> map = new HashMap<String, Object>();

        map.put("username","python1223423");
        map.put("sex","0");
        map.put("birthday",new Date());
        map.put("address","yangguangdadao 13hao");

        userDao.addUserMap(map);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void getUserLike(){

        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);

        List<User> users = userDao.getUserLike("python");

        for (User user:users){

            System.out.println(user);
        }

        logger.info("info:穩得一匹");
        sqlSession.close();
    }



    @Test
    public void getUserByLimit(){

        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);

        HashMap<String,Integer> map = new HashMap<String, Integer>();

        map.put("startIndex",0);
        map.put("pageSize",3);

        List<User> list = userDao.getUserByLimit(map);

        for (User user:list){

            System.out.println(user);
        }
    }

    @Test
    public void getUserByRowBounds(){

        SqlSession sqlSession = MybatisUtil.getSqlSession();

        RowBounds rowBounds = new RowBounds(2,2);

        List<User> userList = sqlSession.selectList("com.zhangpan.mapper.UserDao.getUserByRowBounds",null,rowBounds);
        for (User user:userList){

            System.out.println(user);
        }

    }



}

Mybatis個人筆記

1. 為什麼需要MyBatis

2、第一個Mybatis程式

3、通過配置檔案實作CURD

1. namespace**

繼續閱讀

nginx location中斜線的位置的重要性

27 Best Free Eclipse Plug-ins for Java Developer to be ProductiveCode Quality PluginsText Editor PluginsDependency ManagementVersion Control Integration PluginsFramework Development Continuous Integration Related PluginsOther Utility Plugins

Java String.format方法的簡單使用

neo4j之cypher使用文檔

GitHub連夜封殺！這份阿裡 10W 字内部 Java 字面試手冊到底有多強？

用mybatis的generator插件在項目中自動生成dao及entity

spark/scala關于【資源檔案】加載方法概述外部檔案加載方案測試資源檔案打包入jar包中小結

mybatis_入門程式Mybatis入門

AOP程式設計_Android優雅權限架構(1)概念基礎，2021金三銀四前言正文大綱正文

Effective Java 8:通用程式設計

OOM三種類型

工廠模式-三種類型

【遞歸】高效率求2的n次幂

從mybatis到mybatis plus(mp)

win10本地scala和spark安裝安裝scala安裝spark

scala (3) Function 和 Method