MyBatis源码实现之环境准备

梦里梦外; 2022-04-17 04:44 203阅读 0赞

## 一、引言 ##

*  作为一名Java高级开发人员，阅读源码的功底是其重要的基础技能。除了Spring系列的源码之外，就是MyBatis的源码阅读，好了，废话不多说直接开干。
 *  声明：**这里我使用的3.4.6版本。不同版本之间代码略有差异**。

## 二、搭建 ##

### 1.创建源码阅读项目（Maven方式） ###

#### 1.1 以Maven方式创建项目 ####

在这里我使用的idea创建的（过程略）。效果如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70]

### 2.导入MyBatis相关源码 ###

#### 2.1 下载官方源代码 ####

*  下载地址：[Github MyBatis 官方源码地址][Github MyBatis]
 *  以zip方式下载后进行解压。解压后如下：  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70 1]

#### 2.2 将源代码导入项目中 ####

*  将解压后的src\\main\\java里面的：从org开始，把源文件拷贝到第一步中创建的项目中（以java为根文件），拷贝完毕后如下：  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70 2]
 *  将mybatis-3-mybatis-3.4.6源码包中pom.xml中的依赖拷贝到源码项目的pom.xml中去，并添加上MySql连接的相关依赖。拷贝后代码如下：

<?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.gyoomi</groupId>
        <artifactId>Learning-MyBatis</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>ognl</groupId>
                <artifactId>ognl</artifactId>
                <version>3.1.16</version>
                <scope>compile</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.javassist</groupId>
                <artifactId>javassist</artifactId>
                <version>3.22.0-GA</version>
                <scope>compile</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-api</artifactId>
                <version>1.7.25</version>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-log4j12</artifactId>
                <version>1.7.25</version>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.17</version>
                <optional>true</optional>
            </dependency>
            
            <dependency>
                <groupId>org.apache.logging.log4j</groupId>
                <artifactId>log4j-core</artifactId>
                <version>2.3</version>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>commons-logging</groupId>
                <artifactId>commons-logging</artifactId>
                <version>1.2</version>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>cglib</groupId>
                <artifactId>cglib</artifactId>
                <version>3.2.5</version>
                <optional>true</optional>
            </dependency>
    
            
            <dependency>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
                <version>4.12.2</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.hsqldb</groupId>
                <artifactId>hsqldb</artifactId>
                <version>2.3.5</version> 
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.apache.derby</groupId>
                <artifactId>derby</artifactId>
                <version>10.12.1.1</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.mockito</groupId>
                <artifactId>mockito-core</artifactId>
                <version>2.12.0</version>
                <scope>test</scope>
            </dependency>
            
            <dependency>
                <groupId>commons-dbcp</groupId>
                <artifactId>commons-dbcp</artifactId>
                <version>1.4</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.jboss.spec.javax.transaction</groupId>
                <artifactId>jboss-transaction-api_1.2_spec</artifactId>
                <version>1.0.1.Final</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.apache.velocity</groupId>
                <artifactId>velocity</artifactId>
                <version>1.7</version>
                <scope>test</scope>
            </dependency>
            
            <dependency>
                <groupId>org.postgresql</groupId>
                <artifactId>postgresql</artifactId>
                <version>42.1.4.jre6</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.assertj</groupId>
                <artifactId>assertj-core</artifactId>
                <version>1.7.1</version> 
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>eu.codearte.catch-exception</groupId>
                <artifactId>catch-exception</artifactId>
                <version>1.4.4</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>ru.yandex.qatools.embed</groupId>
                <artifactId>postgresql-embedded</artifactId>
                <version>2.5</version>
                <scope>test</scope>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.6</version>
            </dependency>
    
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.11</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    </project>

### 3.创建测试用例 ###

#### 3.1 创建User表 ####

CREATE TABLE `t_user` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `user_name` varchar(255) DEFAULT NULL,
      `password` varchar(255) DEFAULT NULL,
      `deptment` varchar(255) DEFAULT NULL,
      `phone` varchar(255) DEFAULT NULL,
      `email` varchar(255) DEFAULT NULL,
      `status` int(11) DEFAULT NULL,
      `create_date` datetime DEFAULT NULL,
      `remark` varchar(255) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb4;

#### 3.2 创建UserMapper接口和实现类 ####

*  UserMapper接口

public interface UserMapper {
    	
        User save(User user);
    
    }

*  UserMapper接口实现类

public class UserMapperImpl implements UserMapper {
    
        private static final String NAME_SPACE = "UserMapper.";
        private static SqlSessionFactory ssf;
        private static Reader reader;
    
        static {
            try {
                reader = Resources.getResourceAsReader("mybatis-config.xml");
                ssf = new SqlSessionFactoryBuilder().build(reader);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        @Override
        public User save(User user) {
            SqlSession sqlSession = ssf.openSession();
            int rows = sqlSession.insert(NAME_SPACE + "save", user);
            sqlSession.commit();
            if (rows > 0) {
                return user;
            } else {
                return null;
            }
        }
    }

#### 3.3 创建MyBatis-config.xml和UserMapper.xml文件 ####

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>
    
        <settings>
            <setting name="cacheEnabled" value="true" />
            <setting name="lazyLoadingEnabled" value="true"/>
            <setting name="useGeneratedKeys" value="true"/>
        </settings>
    
        <typeAliases>
            <typeAlias type="com.gyoomi.entity.User" alias="User"/>
        </typeAliases>
    
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/test"/>
                    <property name="username" value="root"/>
                    <property name="password" value="root"/>
                </dataSource>
            </environment>
        </environments>
    
        <mappers>
            <mapper resource="UserMapper.xml"/>
        </mappers>
    </configuration>

UserMapper.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="UserMapper">
    
        <insert id="save" parameterType="User">
            <selectKey keyProperty="id" resultType="java.lang.Integer" order="AFTER">
                SELECT LAST_INSERT_ID();
            </selectKey>
            INSERT INTO t_user
                (id, user_name, password, deptment, phone, email, status, create_date, remark)
            VALUES
                (null, #{userName}, #{password}, #{deptment}, #{phone}, #{email}, #{status}, #{createDate}, #{remark})
        </insert>
    </mapper>

#### 3.4 创建测试的Main方法 ####

创建Main.java(其实这里是不规范的，一般是要写JUnit单元测试的。)

public class Main {
        public static void main(String[] args) {
            UserMapper userMapper = new UserMapperImpl();
            User user = new User();
            user.setPassword("123");
            user.setCreateDate(new Date());
            user.setDeptment("研发部门");
            user.setEmail("123@qq.com");
            user.setStatus(1);
            user.setUserName("张三");
            user.setPhone("13888888888");
            user.setRemark("系统默认用户");
            User userToReturn = userMapper.save(user);
            System.out.println(userToReturn);
        }
    }

### 4.测试环境 ###

执行完上述3步后，整体的代码结构如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70 3]  
执行Main方法后，打开数据看到t\_user表新增了一条记录。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zOTcyMzU0NA_size_16_color_FFFFFF_t_70 4]  
支持MyBatis的源码阅读的环境搭建并测试完毕。下面就让我们开始畅快地阅读源码吧！

**Github地址**：[MyBatis源码][MyBatis]

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[Github MyBatis]: https://github.com/mybatis/mybatis-3
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[MyBatis]: https://github.com/gyoomi/Learning-MyBatis