手写 Hibernate 系列
手写 Hibernate ORM 框架 00-hibernate 简介
手写 Hibernate ORM 框架 02-实体 Bean 定义，建表语句自动生成
手写 Hibernate ORM 框架 03-配置文件读取, 数据库连接构建
手写 Hibernate ORM 框架 05-整体效果测试验证
从零手写组件系列
本节内容
hibernate.cfg.xml 配置文件的读取
数据库访问 Connection 的构建
hibernate.cfg.xml 读取
当然，代码中为了快速模拟，我们也可以将属性 hard code。
但此处为了模拟，就进行简单的实现
文件内容
- hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<hibernate-configuration>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
</hibernate-configuration>
读取测试
- 测试
package com.ryo.hibernate.simulator.dom4j;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.junit.Test;
import java.util.Iterator;
/**
* Created by houbinbin on 16/6/5.
*/
public class HibernateConfigRead {
@Test
public void testRead() throws Exception {
System.out.println(getClass().getClassLoader().getResource("hibernate.cfg.xml"));
SAXReader reader = new SAXReader();
Document document = reader.read(getClass().getClassLoader().getResource("hibernate.cfg.xml"));
Element root = document.getRootElement();
// iterate through child elements of root
for (Iterator i = root.elementIterator(); i.hasNext(); ) {
Element element = (Element) i.next();
System.out.println(element.attributeValue("name"));
System.out.println(element.getData()+" == "+element.getText()); //获取值
}
}
}
- 结果
file:/Users/houbinbin/code/_orm/hibernate-simulator/target/classes/hibernate.cfg.xml
connection.driver_class
com.mysql.jdbc.Driver == com.mysql.jdbc.Driver
connection.url
jdbc:mysql://localhost:3306/hibernate == jdbc:mysql://localhost:3306/hibernate
connection.username
root == root
connection.password
123456 == 123456
构建 Connetion
数据库链接构建
package com.ryo.hibernate.simulator.hibernate.util;
import com.mysql.jdbc.Connection;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* 数据库链接信息
*
* @author houbinbin
* @date 16/6/5
*/
public class ConnectionUtil {
private ConnectionUtil() {
}
/**
* 根据配置信息 获取数据库链接
*
* @return Connection
*/
public static Connection getConnection() {
Connection connection = null;
Map<String, String> config = getJDBCConfig();
try {
Class.forName(config.get("connection.driver_class"));
connection = (Connection) DriverManager.getConnection(config.get("connection.url"), config.get("connection.username"),
config.get("connection.password"));
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
return connection;
}
/**
* 获取 JDBC 配置信息
*
* @return map
*/
private static Map<String, String> getJDBCConfig() {
Map<String, String> config = new HashMap<>();
SAXReader reader = new SAXReader();
Document document = null;
try {
document = reader.read(ConnectionUtil.class.getClassLoader().getResource("hibernate.cfg.xml"));
} catch (DocumentException e) {
e.printStackTrace();
}
assert document != null;
Element root = document.getRootElement();
for (Iterator i = root.elementIterator(); i.hasNext(); ) {
Element element = (Element) i.next();
config.put(element.attributeValue("name"), element.getText());
}
return config;
}
}
