mybatis模拟04

create SqlSession Class

package com.wsd.core;

/**
 * @description: 执行sql
 * @author: Mr.Wang
 * @create: 2023-06-24 16:55
 **/
public class SqlSession {
}

SqlSessionFactory 中创建 openSqlSession method to get a sql session instance

 /**
     * @description Get sql session instance
     * @param null        
     * @return 
     */
    public SqlSession openSqlSession(){
        return null;
    }

package com.wsd.core;

import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-22 21:39
 **/
public class SqlSessionFactory {


    /**
     * @description 事务管理器 transactionManager
     * 根据配置的不同而使用不同的实现类
     */
    private Transaction transaction;

    /**
     * @description
     * map 的 key 为 sql标签的 id , value 为MappedStatement 对象
     * The key of the map is the id of the SQL tag, and the value is the MappedStatement object
     */
    private Map<String,MappedStatement> mappedStatementMap;

    public SqlSessionFactory(Transaction transaction, Map<String, MappedStatement> mappedStatementMap) {
        this.transaction = transaction;
        this.mappedStatementMap = mappedStatementMap;
    }

    /**
     * @description Get sql session instance
     * @param null
     * @return
     */
    public SqlSession openSqlSession(){
        return null;
    }
}

SqlSessionFactory 中创建 openSqlSession method to get a sql session instance

获取 sql session instance,需要先有一个connection

 /**
     * @description Get sql session instance
     * @param null
     * @return
     */
    public SqlSession openSqlSession(){
        //创建connection
        this.transaction.openConnection();

        return null;
    }

//创建SqlSession instance，将 this 作为参数传给SqlSession instance ，sqlSession 就可以使用 SqlSessionFactory 的属性

SqlSession sqlSession = new SqlSession(this);

 /**
     * @description Get sql session instance
     * @param null
     * @return
     */
    public SqlSession openSqlSession(){
        //创建connection
        this.transaction.openConnection();

        //创建SqlSession instance
        SqlSession sqlSession = new SqlSession(this);

        return sqlSession;
    }

SqlSession 添加属性和构造方法

package com.wsd.core;

/**
 * @description: 执行sql
 * @author: Mr.Wang
 * @create: 2023-06-24 16:55
 **/
public class SqlSession {
    
    private SqlSessionFactory sqlSessionFactory;

    public SqlSession(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }
}

添加 insert 方法，执行 insert sql语句

/**
 * @description 执行 inert ,向数据库表中插入数据
 * @param sqlId：sql 语句的 id
 * @param data:所需要的数据
 * @return 成功插入的记录数量
 */
public int insert(String sqlId, Object data){
    return 0;
}

package com.wsd.core;

/**
 * @description: 执行sql
 * @author: Mr.Wang
 * @create: 2023-06-24 16:55
 **/
public class SqlSession {

    private SqlSessionFactory sqlSessionFactory;

    public SqlSession(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    /**
     * @description 执行 inert ,向数据库表中插入数据
     * @param sqlId：sql 语句的 id
     * @param data:所需要的数据
     * @return 成功插入的记录数量
     */
    public int insert(String sqlId, Object data){
        return 0;
    }
}

SqlSessionFactory 添加获取 属性的get方法

public Transaction getTransaction() {
    return transaction;
}

public Map<String, MappedStatement> getMappedStatementMap() {
    return mappedStatementMap;
}

package com.wsd.core;

import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-22 21:39
 **/
public class SqlSessionFactory {


    /**
     * @description 事务管理器 transactionManager
     * 根据配置的不同而使用不同的实现类
     */
    private Transaction transaction;

    /**
     * @description
     * map 的 key 为 sql标签的 id , value 为MappedStatement 对象
     * The key of the map is the id of the SQL tag, and the value is the MappedStatement object
     */
    private Map<String,MappedStatement> mappedStatementMap;

    public SqlSessionFactory(Transaction transaction, Map<String, MappedStatement> mappedStatementMap) {
        this.transaction = transaction;
        this.mappedStatementMap = mappedStatementMap;
    }

    /**
     * @description Get sql session instance
     * @param null
     * @return
     */
    public SqlSession openSqlSession(){
        //创建connection
        this.transaction.openConnection();

        //创建SqlSession instance
        SqlSession sqlSession = new SqlSession(this);

        return sqlSession;
    }

    public Transaction getTransaction() {
        return transaction;
    }

    public Map<String, MappedStatement> getMappedStatementMap() {
        return mappedStatementMap;
    }
}

SqlSession 添加以下方法

/**
 * @description commit transaction
 * @param null        
 * @return 
 */
public void commit(){
    this.sqlSessionFactory.getTransaction().commit();
}

/**
 * @description rollback transaction 
 * @param null        
 * @return 
 */
public void rollback(){
    this.sqlSessionFactory.getTransaction().rollback();
}

/**
 * @description close connection
 * @param null        
 * @return 
 */
public void close(){
    this.sqlSessionFactory.getTransaction().close();
}

package com.wsd.core;

/**
 * @description: 执行sql
 * @author: Mr.Wang
 * @create: 2023-06-24 16:55
 **/
public class SqlSession {

    private SqlSessionFactory sqlSessionFactory;

    public SqlSession(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    /**
     * @description 执行 inert ,向数据库表中插入数据
     * @param sqlId：sql 语句的 id
     * @param data:所需要的数据
     * @return 成功插入的记录数量
     */
    public int insert(String sqlId, Object data){
        return 0;
    }

    /**
     * @description commit transaction
     * @param null
     * @return
     */
    public void commit(){
        this.sqlSessionFactory.getTransaction().commit();
    }

    /**
     * @description rollback transaction
     * @param null
     * @return
     */
    public void rollback(){
        this.sqlSessionFactory.getTransaction().rollback();
    }

    /**
     * @description close connection
     * @param null
     * @return
     */
    public void close(){
        this.sqlSessionFactory.getTransaction().close();
    }
}

实现 insert method of SqlSession

/**
 * @description 执行 inert ,向数据库表中插入数据
 * @param sqlId：sql 语句的 id
 * @param data:所需要的数据
 * @return 成功插入的记录数量
 */
public int insert(String sqlId, Object data){
    
    try {
        //Get connection
        Connection connection = this.sqlSessionFactory.getTransaction().getConnection();
        String sql = this.sqlSessionFactory.getMappedStatementMap().get(sqlId).getSql();

        //将 #{} 替换为 ?,"#\\{[0-9A-Za-z_$]*}" 是匹配 #{} 的正则表达式
        String preSql = sql.replaceAll("#\\{[0-9A-Za-z_$]*}", "?");
        PreparedStatement preparedStatement = connection.prepareStatement(preSql);
        //给 ？占位符传递参数
        

    } catch (SQLException e) {
        e.printStackTrace();
    }
    return 0;
}

给？占位符传递参数如何实现？

尝试获取 #{value} 中的 value
public static void main(String[] args) {
    String sql = "insert into t_car (id,car_num,brand,guide_price,produce_time,car_type) values (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})";
    // 按 #{ 分割 
    String[] sqlArray = sql.split("#\\{");
    //分割后sqlArray[0]没有需要的内容，需要的内容再 #{ 之后，所以 从 sqlArray[0] 开始
    for(int i = 1; i < sqlArray.length; i++){
        //找到 } 的位置
        int index = sqlArray[i].indexOf("}");
        // } 之前的内容就是目标
        String value = sqlArray[i].substring(0,index);
        System.out.println(value);
    }
}

继续实现 insert 方法，给？占位符传递参数

/**
 * @description 执行 inert ,向数据库表中插入数据
 * @param sqlId：sql 语句的 id
 * @param data:所需要的数据
 * @return 成功插入的记录数量
 */
public int insert(String sqlId, Object data){

    int count = 0;
    
    try {
        //Get connection
        Connection connection = this.sqlSessionFactory.getTransaction().getConnection();
        String sql = this.sqlSessionFactory.getMappedStatementMap().get(sqlId).getSql();

        //将 #{} 替换为 ?,"#\\{[0-9A-Za-z_$]*}" 是匹配 #{} 的正则表达式
        String preSql = sql.replaceAll("#\\{[0-9A-Za-z_$]*}", "?");
        PreparedStatement preparedStatement = connection.prepareStatement(preSql);

        //获取 #{value} 中的 value
        String[] sqlArray = sql.split("#\\{");
        for(int i = 1; i < sqlArray.length; i++){
            int index = sqlArray[i].indexOf("}");
            String value = sqlArray[i].substring(0,index);
            //给 ？占位符传递参数
            //通过 get 方法 获取对应的属性值
            //获取get 方法的 method name
            String methodName = "get" + value.toUpperCase().charAt(0) + value.substring(1);
            //获取 getter method 
            Method getterdMethod = data.getClass().getDeclaredMethod(methodName);
            //调用 getter method 获取 属性值
            Object propertyValue =  getterdMethod.invoke(data);
            //给 ？占位符传值
            preparedStatement.setString(i,propertyValue.toString());
        }
        //执行 sql
        count = preparedStatement.executeUpdate();

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

    return count;

}

package com.wsd.core;

import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;

/**
 * @description: 执行sql
 * @author: Mr.Wang
 * @create: 2023-06-24 16:55
 **/
public class SqlSession {

    private SqlSessionFactory sqlSessionFactory;

    public SqlSession(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    

    /**
     * @description 执行 inert ,向数据库表中插入数据
     * @param sqlId：sql 语句的 id
     * @param data:所需要的数据
     * @return 成功插入的记录数量
     */
    public int insert(String sqlId, Object data){

        int count = 0;
        
        try {
            //Get connection
            Connection connection = this.sqlSessionFactory.getTransaction().getConnection();
            String sql = this.sqlSessionFactory.getMappedStatementMap().get(sqlId).getSql();

            //将 #{} 替换为 ?,"#\\{[0-9A-Za-z_$]*}" 是匹配 #{} 的正则表达式
            String preSql = sql.replaceAll("#\\{[0-9A-Za-z_$]*}", "?");
            PreparedStatement preparedStatement = connection.prepareStatement(preSql);

            //获取 #{value} 中的 value
            String[] sqlArray = sql.split("#\\{");
            for(int i = 1; i < sqlArray.length; i++){
                int index = sqlArray[i].indexOf("}");
                String value = sqlArray[i].substring(0,index);
                //给 ？占位符传递参数
                //通过 get 方法 获取对应的属性值
                //获取get 方法的 method name
                String methodName = "get" + value.toUpperCase().charAt(0) + value.substring(1);
                //获取 getter method 
                Method getterdMethod = data.getClass().getDeclaredMethod(methodName);
                //调用 getter method 获取 属性值
                Object propertyValue =  getterdMethod.invoke(data);
                //给 ？占位符传值
                preparedStatement.setString(i,propertyValue.toString());
            }
            //执行 sql
            count = preparedStatement.executeUpdate();

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

        return count;

    }



    /**
     * @description commit transaction
     * @param null
     * @return
     */
    public void commit(){
        this.sqlSessionFactory.getTransaction().commit();
    }

    /**
     * @description rollback transaction
     * @param null
     * @return
     */
    public void rollback(){
        this.sqlSessionFactory.getTransaction().rollback();
    }

    /**
     * @description close connection
     * @param null
     * @return
     */
    public void close(){
        this.sqlSessionFactory.getTransaction().close();
    }
}

test insert method

package com.wsd.core;

import com.wsd.core.util.Resources;
import com.wsd.pojo.Car;
import org.junit.Test;

/**
 * @description: test
 * @author: Mr.Wang
 * @create: 2023-06-24 15:40
 **/
public class TestMyBatis {

    @Test
    public void testInsert(){

        try {
            SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
            SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourcesAsStream("mybatis-config.xml"));
            SqlSession sqlSession = sqlSessionFactory.openSqlSession();
            Car car = new Car();
            car.setBrand("轮回");
            car.setCarType("新能源");
            sqlSession.insert("car.insertCar",car);
            sqlSession.commit();
            sqlSession.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

CarMapper.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="car">
    <!--insert sql：保存一个汽车信息-->
    <insert id="insertCar">
        insert into t_car
            (id,brand,car_type)
        values
            (null,#{brand},#{carType})
    </insert>

    <delete id="deleteByCarNum">
        delete from t_car where car_num = #{carNum}
    </delete>

    <update id="updateCarById">
        update t_car set
            car_num = #{carNum},
            brand = #{brand},
            guide_price = #{guidePrice},
            produce_time = #{produceTime},
            car_type = #{carType}
        where id = #{id}
    </update>

    <select id="selectCarById" resultType="com.wsd.pojo.Car">
        select id,car_num as carNum,brand,guide_price as guidePrice,produce_time as produceTime,car_type as carType
        from t_car
        where id = #{id}
    </select>

    <!--虽然结果是List集合，但是resultType属性需要指定的是List集合中元素的类型。-->
    <select id="selectCarAll" resultType="com.wsd.pojo.Car">
        <!--记得使用as起别名，让查询结果的字段名和java类的属性名对应上。-->
        select
        id, car_num as carNum, brand, guide_price as guidePrice, produce_time as produceTime, car_type as carType
        from
        t_car
    </select>
</mapper>

Car Class

package com.wsd.core;

import com.wsd.core.util.Resources;
import com.wsd.pojo.Car;
import org.junit.Test;

/**
 * @description: test
 * @author: Mr.Wang
 * @create: 2023-06-24 15:40
 **/
public class TestMyBatis {

    @Test
    public void testInsert(){

        try {
            SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
            SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourcesAsStream("mybatis-config.xml"));
            SqlSession sqlSession = sqlSessionFactory.openSqlSession();
            Car car = new Car();
            car.setBrand("蓝雨");
            car.setCarType("新能源");
            sqlSession.insert("car.insertCar",car);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

修改：

创建connection and 开启事务

this.connection.setAutoCommit(this.autoCommit);

public void openConnection() {
    if(this.connection == null){
        try {
            this.connection = this.dataSource.getConnection();
            //开启 事务
            this.connection.setAutoCommit(this.autoCommit);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

package com.wsd.core;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

/**
 * @description: Jdbc Transaction
 * @author: Mr.Wang
 * @create: 2023-06-23 09:49
 **/
public class JdbcTransaction implements Transaction {

    private DataSource dataSource;

    private Connection connection;

    //true:自动提交
    private Boolean autoCommit;

    @Override
    public void commit() {
        try {
            this.connection.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void rollback() {
        try {
            this.connection.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void close() {
        try {
            this.connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public JdbcTransaction(DataSource dataSource, Boolean autoCommit) {
        this.dataSource = dataSource;
        this.autoCommit = autoCommit;
    }

    /**
     * @description
     * 获取连接对象,为connection属性赋值,避免重复获取(commit,rollback 等操作需要使用同一个 connection)
     * @return void
     */
    @Override
    public void openConnection() {
        if(this.connection == null){
            try {
                this.connection = this.dataSource.getConnection();
                //开启 事务
                this.connection.setAutoCommit(this.autoCommit);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public Connection getConnection() {
        return this.connection;
    }
}

test result :

修改

输出返回值（插入成功的记录数量）

int count = sqlSession.insert("car.insertCar",car);

System.out.println(count);

@Test
public void testInsert(){

    try {
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourcesAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSqlSession();
        Car car = new Car();
        car.setBrand("兴欣");
        car.setCarType("新能源");
        int count = sqlSession.insert("car.insertCar",car);
        System.out.println(count);
        sqlSession.commit();
        sqlSession.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

package com.wsd.core;

import com.wsd.core.util.Resources;
import com.wsd.pojo.Car;
import org.junit.Test;

/**
 * @description: test
 * @author: Mr.Wang
 * @create: 2023-06-24 15:40
 **/
public class TestMyBatis {

    @Test
    public void testInsert(){

        try {
            SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
            SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourcesAsStream("mybatis-config.xml"));
            SqlSession sqlSession = sqlSessionFactory.openSqlSession();
            Car car = new Car();
            car.setBrand("兴欣");
            car.setCarType("新能源");
            int count = sqlSession.insert("car.insertCar",car);
            System.out.println(count);
            sqlSession.commit();
            sqlSession.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

result ：