JDBC链接数据库

JDBC连接MySQL数据库

Java DataBase Connectivity数据库连接

1.添加驱动

1.在项目目录下添加lib文件夹，并在其中加入mysql-connector-java-5.1.7-bin.jar驱动器。

2.在驱动文件上右键选中build path-->add to build path;

2.注册驱动

DriverManager.registerDriver(new Driver());

3.建立连接

Connection conn =DriverManager.getConnection("jdbc:mysql://localhost/test01","root","123456");
//参数1：协议+访问的数据库
//参数2：用户名
//参数3：密码

第一次代码实现：

package com.nike.demo01;

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

import com.nike.demo01.util.JDBCUtil;

//import com.mysql.jdbc.Driver;

public class Test01 {
    private static String url = "jdbc:mysql://localhost/test01?useUnicode=true&characterEncoding=utf8";
    private static String user = "root";
    private static String pwd = "Hwp971102";
    
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            //注册驱动
            //DriverManager.registerDriver(new Driver());
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            //建立链接
            conn = DriverManager.getConnection(url, user, pwd);
            st = conn.createStatement();
            String sql = "SELECT * FROM stu";
            rs = st.executeQuery(sql);
            while(rs.next()){
                String id = rs.getString("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                System.out.println(id + "\t" + name +"\t" + age);
            }
            rs.close();
            st.close();
            conn.close();
                    
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            JDBCUtil.release(conn, st, rs);
        }
    }
}

package com.nike.demo01.util;

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

public class JDBCUtil {
    
    public static void release(Connection conn,Statement st,ResultSet rs){
        closeConn(conn);
        closeSt(st);
        closeRs(rs);
    }
    
    public static void closeConn(Connection conn){
        
        try {
            if(conn != null){
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            conn = null;
        }
        
    }
    
    public static void closeSt(Statement st){
        try {
            if(st != null){
                st.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            st = null;
        }
        
    }
    public static void closeRs(ResultSet rs){
        try {
            if(rs != null){
                rs.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            rs = null;
        }        
    }
}

//注册驱动
//DriverManager.registerDriver(new Driver());
Class.forName("com.mysql.jdbc.Driver").newInstance();
//建立链接
conn = DriverManager.getConnection(url, user, pwd);
//Driver 这个类里面有静态代码块，一上来就执行了，所以等同于我们注册了两遍驱动。

JDBC工具类

1.创建properties配置文件，在src目录下声明一个xxx.properties文件。

 

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/test01?useUnicode=true&characterEncoding=utf8
user=root
pwd=Hwp971102

 

2.读取properties文件。

    static {
        try {
            Properties properies = new Properties();
            InputStream is = JDBCUtil.class.getClassLoader()
                    .getResourceAsStream("sql.properies");
          properies.load(is);
            driver = properies.getProperty("driverClass");
            url = properies.getProperty("url");
            user = properies.getProperty("user");
            pwd = properies.getProperty("pwd");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }