标准获得连接和关闭连接模板

模板一：

package js;

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

public class JdbcUtil {
    private static String url="jdbc:mysql://localhost:3306/day01";
    private static String user="root";
    private static String password="root";
    
    static{
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            throw new RuntimeException();
        }
    }
    
    /*
     * 获取连接
     */
    public static Connection getConnection(){
        try {
            Connection conn= DriverManager.getConnection(url, user, password);
            return conn;
        } catch (SQLException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }    
    }
    
    public static void close(Connection conn,Statement smt,ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
        if(smt!=null){
            try {
                smt.close();
            } catch (SQLException e) {
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
    }
}

 在配置文件中读取信息：

db.properties：

url=jdbc:mysql://localhost:3306/day01
user=root
password=root
driverClass=com.mysql.jdbc.Driver

模板二：

package js;

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



public class JdbcUtil {
    private static String url=null;
    private static String user=null;
    private static String password=null;
    private static String driverClass=null;
    static{
        
        try {
            /*
             * 使用类路径的读取方式：
             *   / :斜杠标示classpath的根目录
             *      在java项目下：classpath的根目录从bin开始
             *      在web 项目下:classpath的根目录从WEB-INF/classes目录开始
             */
            //读取db.properties文件
            Properties props=new Properties();
            InputStream in= JdbcUtil.class.getResourceAsStream("/db.properties");
            props.load(in);
            url=(String) props.get("url");
            user=props.getProperty("user");
            password=props.getProperty("password");
            driverClass=props.getProperty("driverClass");
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        try {
            Class.forName(driverClass);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            throw new RuntimeException();
        }
    }
    
    /*
     * 获取连接
     */
    public static Connection getConnection(){
        try {
            Connection conn= DriverManager.getConnection(url, user, password);
            return conn;
        } catch (SQLException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }    
    }
    /*
     * 关闭连接
     */
    public static void close(Connection conn,Statement smt,ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
        if(smt!=null){
            try {
                smt.close();
            } catch (SQLException e) {
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
                throw new RuntimeException(e);
            }
        }
    }
}