mybatis學習筆記 【1】

1. 創建maven專案并添加相關依賴

<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
       <dependency>
           <groupId>org.mybatis</groupId>
           <artifactId>mybatis</artifactId>
           <version>3.4.6</version>
       </dependency>

       <!-- https://mvnrepository.com/artifact/junit/junit -->
       <dependency>
           <groupId>junit</groupId>
           <artifactId>junit</artifactId>
           <version>4.13.2</version>
           <scope>test</scope>
       </dependency>

       <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
       <dependency>
           <groupId>mysql</groupId>
           <artifactId>mysql-connector-java</artifactId>
           <version>5.1.47</version>
       </dependency>

       <!-- https://mvnrepository.com/artifact/log4j/log4j -->
       <dependency>
           <groupId>log4j</groupId>
           <artifactId>log4j</artifactId>
           <version>1.2.17</version>
       </dependency>

       <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
       <dependency>
           <groupId>org.projectlombok</groupId>
           <artifactId>lombok</artifactId>
           <version>1.18.12</version>
           <scope>provided</scope>
       </dependency>

2. 創建資料庫和表并添加資料

CREATE DATABASE testdb;

USE testdb;

CREATE TABLE `t_user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `address` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

INSERT INTO `t_user` VALUES ('1', '李洪剛', '20', '江陽區嘉裕花園3棟四樓15#');
INSERT INTO `t_user` VALUES ('2', '王云華', '30', '納溪區大渡鎮紅魚村三大隊');
INSERT INTO `t_user` VALUES ('3', '鄭小翠', '21', '江陽區老窖花園2棟五樓15號');

3. 在resource目錄下創建jdbc.properties檔案,添加以下內容

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/testdb?useSSL=false
jdbc.username=root
jdbc.password=1

4. 在resource目錄下創建mybatis組態檔mybatis-config.xml

<?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>
    <!-- 添加properties組態檔路徑 -->
    <properties resource="jdbc.properties"/>
    <!--  配置物體類別名  -->
    <typeAliases>
        <package name="com.cxh.entity"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>

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

5. 創建物體類包entity，創建物體類User

package com.cxh.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Integer id;
    private String name;
    private Integer age;
    private String address;
}

6. 創建dao包，創建UserDao

package com.cxh.dao;

import com.cxh.entity.User;

import java.util.List;

public interface UserDao {

    User findById(Integer id);
    List<User> findAll();
}

7. 在resource目錄下創建mapper檔案夾，在mapper檔案夾下創建UserDaoMapper.xml

<?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="com.cxh.dao.UserDao">
    <select id="findById" parameterType="Integer" resultType="User">
        select * from t_user where id=#{id};
    </select>

    <select id="findAll" resultType="User">
        select * from t_user;
    </select>
</mapper>

8. 在resource目錄下創建log4j.properties

log4j.rootLogger=WARN, stdout, logfile
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

9. 創建測驗類

package com.cxh.mappertest;

import com.cxh.dao.UserDao;
import com.cxh.entity.User;
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.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.Reader;
import java.util.List;

/**
 * 測驗用戶操作
 */
public class TestUserOperation {

    private SqlSession sqlSession; //sql會話


    @Before
    public void init() throws IOException {
        //讀取mybatis組態檔
        Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
        //基于mybatis組態檔構建sql會話工廠
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        //通過工場獲得鏈接物件
        sqlSession = sqlSessionFactory.openSession();
        System.out.println("sqlSession啟動...");
    }

    @Test
    public void testFindId(){
        int id = 1;
        //通過介面獲取介面實作類物件
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        User user = mapper.findById(id);
        System.out.println(user == null? "id為["+id+"]的用戶未找到" : user);
    }

    @Test
    public void testFindAll(){
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        List<User> users = mapper.findAll();
        users.forEach(System.out :: println);
    }

    @After
    public void destroy(){
        sqlSession.close();
        System.out.println("sqlSession關閉...");
    }
}

運行結果