MyBatis源码- SqlSession门面模式 & selectList 源码解析

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如果MyBatis的基础用法还不熟悉，31篇入门博客拿走不谢

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工程概览

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pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.artisan</groupId>
    <artifactId>mybatisSource</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.17</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.1</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml
                
                true
            
            
                src/test/java
                
                    **/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>

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mybatis-config.xml

<configuration>

     <properties resource="app.properties">
    properties>
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>

    settings>
    <typeAliases>
    typeAliases>

    <environments default="dev">
        <environment id="dev">
            <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>
        <package name="com.artisan"/>
    mappers>
configuration>

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UserMapper

 package com.artisan;

import com.artisan.bean.User;
import org.apache.ibatis.annotations.Select;


public interface UserMapper {
    @Select({"select * from users where id = #{id}"})
    User selectByid(Integer id);
}

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测试类

基类

 
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;


/**
 *  基类
 */
public class BaseTest {

    public SqlSessionFactory factory;
    public Configuration configuration; 

    @Before
    public void inin(){
        // 获取构建器
        SqlSessionFactoryBuilder factoryBuilder = new SqlSessionFactoryBuilder();
        // 解析xml ,构建会话工厂
        factory = factoryBuilder.build(SqlSessionTest.class.getResourceAsStream("/mybatis-config.xml"));
        // 获取 configuration 这个大管家
        configuration = factory.getConfiguration();
    }
}

SqlSessionTest 测试类

package com.artisan;

import com.artisan.bean.User;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

 
public class SqlSessionTest  extends  BaseTest{

    private MappedStatement ms;

    @Test
    public void sqlSessionTest(){

        // 获取statement SQL映射
        ms = configuration.getMappedStatement("com.artisan.UserMapper.selectByid");

        // 开启会话  第一个参数 执行器类型  第二个参数 是否自动提交
        SqlSession sqlSession = factory.openSession(ExecutorType.SIMPLE, true);
        // 门面模式 屏蔽了底层调用的复杂用  统一对接sqlSession
        List<User> users = sqlSession.selectList(ms.getId(), 1);
        System.out.println(users.get(0));

    }
}

测试结果：

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selectList 源码解析

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附

SQL

/*
Navicat MySQL Data Transfer

Source Server         : localhost_root
Source Server Version : 80011
Source Host           : 127.0.0.1:3306
Source Database       : artisan

Target Server Type    : MYSQL
Target Server Version : 80011
File Encoding         : 65001

Date: 2020-06-14 00:46:05
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for `users`
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `age` varchar(255) DEFAULT NULL,
  `sex` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  `phoneNumber` varchar(255) DEFAULT NULL,
  `createTime` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of users
-- ----------------------------
INSERT INTO `users` VALUES ('1', 'artisan', '11', 'male', '[email protected]', '12345', '2020-06-04');

log4j.properties

### set log levels ###
log4j.rootLogger = DEBUG ,stdout

### 
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern =  %d{ABSOLUTE} %5p %c:%L - %m%n

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app.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/artisan?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT
jdbc.username=root
jdbc.password=root
default.environment=dev

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User

package com.artisan.bean;


import java.util.Date;

public class User implements java.io.Serializable {
    private Integer id;
    private String name;
    private String age;
    private String sex;
    private String email;
    private String phoneNumber;
    private Date createTime;

    public User() {
    }

    public User(Integer id, String name) {
        this.id = id;
        this.name = name;
    }
    ....省略 set/get 
    ....
}