Java系列-读取properties文件连接数据库

简介：将数据库的信息（数据库驱动driver、数据库url、用户名和密码）放在db.properties文件中，然后在java类中将这些数据取出来，做一个简单的数据库连接测试。

db.properties文件放在src目录下，源码：

db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/hibernate
username=root
password=123456

编写一个读取properties属性文件的方法类PropertiesUtils

PropertiesUtils.java

package com.xuxu.util;

import java.io.IOException;
import java.util.Properties;

public class PropertiesUtils {
	static Properties property = new Properties();
	public static boolean loadFile(String fileName){ 
		try {
			property.load(PropertiesUtils.class.getClassLoader().getResourceAsStream(fileName));
		} catch (IOException e) {
			e.printStackTrace();
			return false;   
		}   
		return true;
	}
	public static String getPropertyValue(String key){   
		return property.getProperty(key);
	}
}

连接数据库的类DBUtil

DBUtil.java

package com.xuxu.util;

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

public class DBUtil {
	public Connection conn= null;
	public Statement stmt= null;
	public ResultSet rs= null;
	
	public DBUtil(){}
	
	public static Connection getConnection(){
		PropertiesUtils.loadFile("db.properties");
		String url = PropertiesUtils.getPropertyValue("url");
		String username = PropertiesUtils.getPropertyValue("username");
		String password = PropertiesUtils.getPropertyValue("password");  
		String driver = PropertiesUtils.getPropertyValue("driver");  
		
		Connection conn = null;  
		try {
			Class.forName(driver);
			conn = DriverManager.getConnection(url,username,password);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		if(conn==null){
			System.out.println("error!!!!!");
		}
		return conn;
	}
	
	public static void main(String[] args) {
		System.out.println(DBUtil.getConnection());
	}
}

经测试，运行正常！