JDBC自定义XML

JDBC自定义XML

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1. 定义配置文件

创建自定义xml 文件, 保存 数据库连接信息

jdbc-config.xml代码如下：

<?xml version="1.0" encoding="UTF-8" ?>
<jdbc>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://localhost:3306/db5?characterEncoding=UTF-8</property>
    <property name="user">root</property>
    <property name="password">123456</property>
</jdbc>

2. 编写工具类(配置式)

编写工具类 ,使用xpath 读取数据库信息，代码如下：

package com.lagou.xml05;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class JDBCUtils {

    //1.定义字符串变量 保存连接信息
    public static String DRIVERNAME;
    public static String URL;
    public static String USER;
    public static String PASSWORD;

    //2.静态代码块
    static{
        //使用 XPath语法 对xml中的数据进行读取
        SAXReader reader = new SAXReader();
        try {
            Document document = reader.read("H:\\jdbc_work\\xml_task03\\src\\com\\lagou\\xml05\\jdbc-config.xml");

            //1.获取驱动名称
            Node driver = document.selectSingleNode("/jdbc/property[@name='driverClass']");
            DRIVERNAME = driver.getText();

            //2.获取URL
            Node url = document.selectSingleNode("/jdbc/property[@name='jdbcUrl']");
            URL = url.getText();

            //3.获取用户名
            Node user = document.selectSingleNode("/jdbc/property[@name='user']");
            USER = user.getText();

            //4.获取密码
            Node password = document.selectSingleNode("/jdbc/property[@name='password']");
            PASSWORD = password.getText();

            //注册驱动
            Class.forName(DRIVERNAME);

        } catch (Exception e) {
            e.printStackTrace();
        }

    }


    //获取连接
    public static Connection getConnection(){

        try {

            Connection connection = DriverManager.getConnection(URL, USER, PASSWORD);

            return connection;
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }

    }

}

3. 测试工具类

代码如下：

package com.lagou.xml05;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestJDBC {

    //查询所有员工信息
    public static void main(String[] args) throws SQLException {

        //1.获取连接
        Connection connection = JDBCUtils.getConnection();

        //2.获取Statement 对象 执行SQL
        Statement statement = connection.createStatement();
        ResultSet resultSet = statement.executeQuery("select * from employee");

        //3.处理结果集
        while(resultSet.next()){

            String name = resultSet.getString("ename");
            System.out.println("员工的姓名: " + name);
        }

        //4.关闭资源
        resultSet.close();
        statement.close();
        connection.close();

    }

}

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