2016-04-22jdbc工具类优化，外部资源加载，类加载器，Properties

Posted 2022-12-03 暴走灬青春

package com.heima.utils;

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

public class JdbcUtils 
    static String url;
    static String user;
    static String password;
    static String driverClass;
    static 
        //创建加载外部内容的对象  保存以key value 格式
        Properties props = new Properties();

        try 
            //通过类加载器的方式获得外部文件的流 配置文件必须放在src目录下
            InputStream in = 
                    JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");
            //加载外部文件的内容
            props.load(in);
         catch (IOException e1) 
            // TODO Auto-generated catch block
            e1.printStackTrace();
        

        try 
            driverClass = props.getProperty("driverClass");
            Class.forName(driverClass);

         catch (ClassNotFoundException e) 
            // TODO Auto-generated catch block
            e.printStackTrace();
        
         url = props.getProperty("url");
         user = props.getProperty("user");
         password = props.getProperty("password");
    
     public static Connection getConn() throws SQLException 
        //获得连接
        Connection conn = DriverManager.getConnection(url, user, password);
        return conn;
    
    public static void release(ResultSet rs,PreparedStatement stmt,Connection conn)
        try 
            if(rs != null)
                rs.close();
            
            rs = null;
         catch (Exception e2) 
        
        release(stmt,conn);
    
    public static void release(PreparedStatement stmt,Connection conn)
        try 
            if( stmt != null)
                stmt.close();
            
            stmt = null;
         catch (Exception e2) 

        
        try 
            if( conn != null)
                conn.close();
            
            conn = null;
         catch (Exception e2) 
        
    

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mytest
user=root
password=123456