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学习资料视频来源：https://www.bilibili.com/video/BV1R14y1W7yS

1. 项目介绍

1.1 项目结构

项目分为2个模块，ipersistent 和ipersistent-test。ipersistent为框架，ipersistent-test为框架使用端，ipersistent-test依赖ipersistent。视频里是使用maven管理项目，我这里是使用gradle管理项目。目录结构如下：

1.2 项目依赖

(1) ipersistent依赖

plugins {id 'java-library'
}group = 'com.mql'repositories {maven {url 'https://maven.aliyun.com/nexus/content/groups/public/'}mavenCentral()
}dependencies {testImplementation platform('org.junit:junit-bom:5.10.0')testImplementation 'org.junit.jupiter:junit-jupiter'// 引入dom4j依赖，用于解析xml文件api 'dom4j:dom4j:1.6.1'runtimeOnly 'mysql:mysql-connector-java:5.1.40'//阿里德鲁伊数据库连接池implementation ('com.alibaba:druid:1.2.8') implementation 'jaxen:jaxen:1.2.0' annotationProcessor 'org.projectlombok:lombok:1.18.20'compileOnly 'org.projectlombok:lombok:1.18.20'
}

(2) ipersistent-test依赖

plugins {id 'java'
}group = 'com.mql'repositories {mavenCentral()
}dependencies {testImplementation platform('org.junit:junit-bom:5.10.0')testImplementation 'org.junit.jupiter:junit-jupiter'// 引用ipersistentimplementation project(':ipersistent')implementation 'org.apache.logging.log4j:log4j-core:2.14.1'implementation 'org.apache.logging.log4j:log4j-api:2.14.1'
}test {useJUnitPlatform()
}

1.3 配置文件

核心配置文件映射配置文件，都是在ipersistent-test提供。

(1) 核心配置文件

<configuration><!-- 数据源配置 --><datasource><property name="driverClassName" 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><mappers><mapper resource="mapper/UserMapper.xml"/></mappers>
</configuration>

(2) 映射配置文件

<mapper namespace="user"><!--    唯一标识: namespace.id--><!-- 查询所有用户 --><select id="selectList" resultType="com.mqlyes.pojo.User">select * from user</select><!-- 按条件查询用户 --><!--    --><select id="selectOne" resultType="com.mqlyes.pojo.User" parameterType="com.mqlyes.pojo.User">select * from user where id = #{id} and username = #{username}</select>
</mapper>

2. 核心源码类

2.1 ipersistent

Resources

作用：根据路径，加载配置文件，并转换成字节流，比较简单。

public class Resources {/*** 根据配置文件的路径加载配置文件存到内存中* @param path* @return*/public static InputStream getResource(String path) {return Resources.class.getClassLoader().getResourceAsStream(path);}
}

Configuration

作用：Configuration存储核心配置和映射配置文件解析出的配置信息。分别对应dataSource和mappedStatementMap。

/*** 存数据库配置信息 从sqlMapper.xml中解析出的东西*/
public class Configuration {// 数据源对象private DataSource dataSource;// key为 statementIDprivate Map<String, MappedStatement> mappedStatementMap = new HashMap<>();public DataSource getDataSource() {return dataSource;}public void setDataSource(DataSource dataSource) {this.dataSource = dataSource;}public Map<String, MappedStatement> getMappedStatementMap() {return mappedStatementMap;}public void setMappedStatementMap(Map<String, MappedStatement> mappedStatementMap) {this.mappedStatementMap = mappedStatementMap;}
}

MappedStatement

作用：存储映射配置文件中解析出信息，一个MappedStatement对应一个xxxmapper.xml文件

public class MappedStatement {// 唯一标识private String StatementID;private String resultType;private String parameterType;private String sql;public String getStatementID() {return StatementID;}public void setStatementID(String statementID) {StatementID = statementID;}public String getResultType() {return resultType;}public void setResultType(String resultType) {this.resultType = resultType;}public String getParameterType() {return parameterType;}public void setParameterType(String parameterType) {this.parameterType = parameterType;}public String getSql() {return sql;}public void setSql(String sql) {this.sql = sql;}
}

XMLConfigBuilder

作用：先解析核心配置文件中数据库配置信息，封装成Datasource。再解析mapper文件所有路径
调用XMLMapperBuilder解析mapper文件，并封装进MappedStatement。解析二者的过程中，把Datasource和MappedStatement封装进Configuration。

public class XMLConfigBuilder {private Configuration configuration;public XMLConfigBuilder() {this.configuration = new Configuration();}/*** 解析配置文件 封装到Configuration中** @param inputStream* @return*/public Configuration parse(InputStream inputStream) throws DocumentException {Document document = new SAXReader().read(inputStream);Element rootElement = document.getRootElement();List<Element> list = rootElement.selectNodes("//property");Properties properties = new Properties();for (Element element : list) {String name = element.attributeValue("name");String value = element.attributeValue("value");properties.put(name, value);}// 创建数据源对象DruidDataSource druidDataSource = new DruidDataSource();druidDataSource.setDriverClassName(properties.getProperty("driver"));druidDataSource.setUrl(properties.getProperty("url"));druidDataSource.setUsername(properties.getProperty("username"));druidDataSource.setPassword(properties.getProperty("password"));configuration.setDataSource(druidDataSource);// 获取映射配置文件路径List<Element> mapperList = rootElement.selectNodes("//mapper");for (Element element : mapperList) {String mapperPath = element.attributeValue("resource");InputStream resource = Resources.getResource(mapperPath);XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(configuration);xmlMapperBuilder.parse(resource);}return configuration;}
}

XMLMapperBuilder

public class XMLMapperBuilder {private Configuration configuration;public XMLMapperBuilder(Configuration configuration) {this.configuration = configuration;}public   void parse(InputStream inputStream) throws DocumentException {Document document = new SAXReader().read(inputStream);Element rootElement = document.getRootElement();String namespace = rootElement.attributeValue("namespace");List<Element> elements = rootElement.selectNodes("//select");for (Element element : elements) {String id = element.attributeValue("id");String resultType = element.attributeValue("resultType");String parameterType = element.attributeValue("parameterType");String sql = element.getTextTrim();MappedStatement mappedStatement = new MappedStatement();mappedStatement.setStatementID(namespace + "." + id);mappedStatement.setSql(sql);mappedStatement.setResultType(resultType);mappedStatement.setParameterType(parameterType);configuration.getMappedStatementMap().put(mappedStatement.getStatementID(), mappedStatement);}}
}

SqlSessionFactoryBuilder

public class SqlSessionFactoryBuilder {public SqlSessionFactory build(InputStream inputStream) throws DocumentException {XMLConfigBuilder xmlConfigBuilder = new XMLConfigBuilder();Configuration configuration = xmlConfigBuilder.parse(inputStream);// 创建SqlSessionFactory工厂对想DefaultSqlSessionFactory defaultSqlSessionFactory = new DefaultSqlSessionFactory(configuration);return defaultSqlSessionFactory;}}

SqlSessionFactory

public interface SqlSessionFactory {
}

DefaultSqlSessionFactory

public class DefaultSqlSessionFactory implements SqlSessionFactory {private Configuration configuration;public DefaultSqlSessionFactory(Configuration configuration) {this.configuration = configuration;}
}

2.2 ipersistent-test

测试类

使用端目前只有一个测试类,看返回结果中的configuration对象信息是否完整。

public class IpersistentTest {@Testpublic void test1() throws Exception {InputStream resource = Resources.getResource("sqlMapConfig.xml");SqlSessionFactory build = new SqlSessionFactoryBuilder().build(resource);System.out.println(build);}
}