JAVA加载配置文件的两种方式

版权声明：本文为博主原创文章，转载请声明出处。 https://blog.csdn.net/qq_34909297/article/details/79954712

一:

package days_01;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
/*
 
 
 
 
 */

public class DBUtil {
	
	static Properties properties;
	
	static {
		properties = new Properties();
		//去加载配置文件
		try {
			properties.load(new FileReader("./src/db.properties"));
		} 
		 catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public Connection getConnection() throws SQLException{
		String driverClassName = properties.getProperty("driverClassName");
		String url = properties.getProperty("url");
		String username = properties.getProperty("username");
		String password = properties.getProperty("password");
		// 加载驱动类
				try {
					Class.forName(driverClassName);
				} catch (ClassNotFoundException e) {
					throw new RuntimeException(e);
				}
		return DriverManager.getConnection(url,username,password);
	}
	public static void main(String[] args) throws SQLException {
		System.out.println("用户名:"+properties.getProperty("username")+"密码:"+properties.getProperty("password"));
		System.out.println("用户名:"+properties.getProperty("url")+"密码:"+properties.getProperty("driverClassName"));
		DBUtil db = new DBUtil();
		Connection conn = db.getConnection();
		System.out.println(conn);
	}
}

package day_01;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

/**
 * v1.0
 * @author cxf
 *
 */
public class JdbcUtils {
	private static Properties props = null;
	
	// 只在JdbcUtils类被加载时执行一次！
	static {
		// 给props进行初始化，即加载dbconfig.properties文件到props对象中
		try {
			props = new Properties();
			InputStream in = JdbcUtils.class.getClassLoader()
					.getResourceAsStream("dbconfig.properties");
			props.load(in);
		} catch(IOException e) {
			throw new RuntimeException(e);
		}
		
		// 加载驱动类
		try {
			Class.forName(props.getProperty("driverClassName"));
		} catch (ClassNotFoundException e) {
			throw new RuntimeException(e);
		}
	}
	
	// 获取连接!
	public static Connection getConnection() throws SQLException {
		// 得到Connection
		return DriverManager.getConnection(props.getProperty("url"),
				props.getProperty("username"), 
				props.getProperty("password"));
	}
}