Code implementation of custom persistence layer framework 1

Project structure

• Describe the project structure of the custom persistence layer framework?

  • .
    ├── IPersistence
    │ ├── IPersistence.iml
    │ ├── pom.xml
    │ └── src
    └── IPersistence_test
        ├── IPersistence_test.iml
        ├── pom.xml
        ├── src
        └── target
    

Specific code

sqlMapperConfig.xml configuration file

<configuration>
    <!-- Store database configuration information -->
    <dataSource>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/zdy_mybatis"></property>
        <property name="username" value="root"></property>
        <property name="password" value="123456"></property>
    </dataSource>

    <!-- Store the full path of mapper.xml -->
    <mapper resource="UserMapper.xml" />
</configuration>

UserMapper.xml configuration file

<mapper namespace="user">
    <!-- The unique identifier of sql: namespace.id combination: statementId -->
    <select id="selectList" resultType="com.terwergreen.pojo.User">
        select * from user
    </select>
    <select id="selectOne" resultType="com.terwergreen.pojo.User" parameterType="com.terwergreen.pojo.User">
        select * from user where id = #{id} and username = #{username}
    </select>
</mapper>

Read resource processing, Resources class

/**
 * Resource processing class
 *
 * @name: Resource
 * @author: terwer
 * @date: 2022-03-14 12:57
 **/
public class Resources {
    /**
     * According to the path of the configuration file, load the configuration file into a byte input stream and store it in memory
     *
     * @param path
     * @return
     */
    public static InputStream getResourceAsStream(String path) {
        InputStream inputStream = Resources.class.getClassLoader().getResourceAsStream(path);
        return inputStream;
    }
}

SqlSessionFactoryBuider factory construction object

/**
 *Factory construction object
 *
 * @name: SqlSessionFactoryBuilder
 * @author: terwer
 * @date: 2022-03-14 15:18
 **/
public class SqlSessionFactoryBuilder {
    public SqlSessionFactory build(InputStream in) throws DocumentException, PropertyVetoException {
        // 1. Parse the configuration file and encapsulate the parsed content into Configuration.
        XmlConfigBuilder xmlConfigBuilder = new XmlConfigBuilder();
        Configuration configuration = xmlConfigBuilder.parse(in);

        // 2. Create SqlSessionFactory object
        DefaultSqlSessionFactory sqlSessionFactory = new DefaultSqlSessionFactory(configuration);
        return sqlSessionFactory;
    }
}

Configuration file analysis

/**
 * @name: XmlConfigBuilder
 * @author: terwer
 * @date: 2022-03-14 15:40
 **/
public class XmlConfigBuilder {

    private Configuration configuration;

    public XmlConfigBuilder() {
        configuration = new Configuration();
    }

    /**
     * Use dom4j to parse the configuration file and encapsulate the Configuration
     *
     * @param in
     * @return
     */
    public Configuration parse(InputStream in) throws DocumentException, PropertyVetoException {
        Document document = new SAXReader().read(in);
        // <confirmation>
        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.setProperty(name, value);
        }

        ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource();
        comboPooledDataSource.setDriverClass(properties.getProperty("driverClass"));
        comboPooledDataSource.setJdbcUrl(properties.getProperty("jdbcUrl"));
        comboPooledDataSource.setUser(properties.getProperty("username"));
        comboPooledDataSource.setPassword(properties.getProperty("password"));

        configuration.setDataSource(comboPooledDataSource);

        // Parse mapper.xml, get the path, load it into a byte input stream, and parse it
        List<Element> mapperList= rootElement.selectNodes("//mapper");
        // <mapper>
        for (Element element : mapperList) {
            String mapperPath = element.attributeValue("resource");
            InputStream resourceAsStream = Resources.getResourceAsStream(mapperPath);

            XmlMapperBuilder xmlMapperBuilder = new XmlMapperBuilder(configuration);
            xmlMapperBuilder.parse(resourceAsStream);
        }

        return configuration;
    }
}

mapper mapping file analysis

/**
 * mapper parser
 *
 * @name: XmlMapperBuilder
 * @author: terwer
 * @date: 2022-03-14 16:16
 **/
public class XmlMapperBuilder {
    private Configuration configuration;

    public XmlMapperBuilder(Configuration configuration) {
        this.configuration = configuration;
    }

    public void parse(InputStream in) throws DocumentException {
        Document document = new SAXReader().read(in);

        // <mapper>
        Element rootElement = document.getRootElement();
        String namespace = rootElement.attributeValue("namespace");

        List<Element> list = rootElement.selectNodes("//select");
        for (Element element : list) {
            String id = element.attributeValue("id");
            String resultType = element.attributeValue("resultType");
            String parameterType = element.attributeValue("parameterType");

            String sqlText = element.getTextTrim();

            MappedStatement mappedStatement = new MappedStatement();
            mappedStatement.setStatementId(id);
            mappedStatement.setResultType(resultType);
            mappedStatement.setParameterType(parameterType);
            mappedStatement.setSql(sqlText);

            Map<String, MappedStatement> mappedStatementMap = configuration.getMappedStatementMap();
            String statementId = namespace + "." + id;
            mappedStatementMap.put(statementId, mappedStatement);
        }
    }
}

Concrete implementation of SqlSession

/**
 * @name: SqlSession
 * @author: terwer
 * @date: 2022-03-14 16:35
 **/
public interface SqlSession {
    /**
     * Search all
     */
    public <E> List<E> selectList(String statementId, Object... params) throws Exception;

    /**
     * Query a single
     */
    public <T> T selectOne(String statementId, Object... params) throws Exception;

    public <T> T getMapper(Class<?> mapperClass);
}

Article update history

2022/05/08 feat: Optimize code

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