java 链接jdbc

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

public class ConnnectionUtils {

    private static String dbDriver = ""; //com.mysql.jdbc.Driver
    private static String url = "";      //jdbc\:mysql\://localhost\:3306/dabasename?useUnicode\=true&characterEncoding\=UTF-8
    private static String user = "";     //username
    private static String passw = "";    //password
    
    static Connection conn=null;
    
    static {
        
        ResourceBundle source = ResourceBundle.getBundle("config");  //config.properties
        dbDriver = source.getString("driverClassName");
        url = source.getString("jdbc_url");
        user = source.getString("jdbc_username");
        passw = source.getString("jdbc_password");
    }
    
    public static Connection getConnection(){
        try {
            // 加载驱动
            Class.forName(dbDriver);
            // 获取链接
            conn = DriverManager.getConnection(url,user,passw);
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return conn;
    }
    
    //使用后关闭链接
    public static void  close(){
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    
    
    
    public static void main(String[] args) {
        Connection conn = ConnnectionUtils.getConnection();
        System.out.println(conn);
        String sql = "select * from tableName";
        
        try {
            // 执行SQL  
            Statement statement = conn.createStatement();
            // 获得结果集 
            ResultSet result = statement.executeQuery(sql);
            
            //如果有结果集 ，对结果进行处理
            while (result.next()) {
                String app_url = result.getString("oneStringColumnName");
                System.out.println(app_url);
                
            }
            //关闭链接
            ConnnectionUtils.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        
    }
}

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