MySQL数据库的连接

测试类

package MyJdbc;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class JDBCTest {

public static void main(String[] args){

Statement st = null;

ResultSet rs = null;

Connection con = null;

//1.注册驱动

try {

con=JDBCUtil.getCon();

    //3.创建statement对象

st = con.createStatement();

//4.执行查询，得到结果集

String sql="select * from _count";

rs = st.executeQuery(sql);

//5.遍历查询每一条记录

while(rs.next()) {

int id=rs.getInt("id");

String name=rs.getString("name");

String sex=rs.getString("sex");

System.out.println(" id="+id+" , name="+name+" , sex="+sex);

}

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

//6.释放资源

JDBCUtil.Close(rs, st, con);

}

}

}

工具类进行抽取

package MyJdbc;

import java.io.FileInputStream;

import java.io.FileReader;

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 {

//注册驱动

static String driverClass=null;

static String url=null;

static String user=null;

static String password=null;

static {

//创建一个属性配置对象

Properties pro=new Properties();

//创建输入流

//在工程的根目录下创建对象去读取根目录下的文件

//InputStream is=new FileInputStream("JDBC.properties");//error:系统找不见指定路径,,

//使用类加载器去读取src底下的资源文件

InputStream is=JDBCUtil.class.getClassLoader().getResourceAsStream("JDBC.properties");

//导入输入流

try {

pro.load(is);

//读取属性

driverClass = pro.getProperty("driverClass");

url=pro.getProperty("url");

user=pro.getProperty("user");

password=pro.getProperty("password");

} catch (IOException e) {

e.printStackTrace();

}

}

public static Connection getCon() {

Connection con=null;

try {

Class.forName("com.mysql.jdbc.Driver");

con = DriverManager.getConnection(url, user,password);

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}//全路径

//DriverManager.registerDriver(new com.mysql.jdbc.Driver());

//建立连接

catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return con;

}

//释放资源

public static void Close(ResultSet rs,Statement st,Connection con) {

closeRs(rs);

closeSt(st);

closeCon(con);

}

private static void closeRs(ResultSet rs) {

try {

if(rs != null) {

  rs.close();

    }

}catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

rs=null;

}

}

private static void closeSt(Statement st) {

try {

if(st != null) {

  st.close();

    }

}catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

st=null;

}

}

private static void closeCon(Connection con) {

try {

if(con != null) {

  con.close();

    }

}catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

con=null;

}

}

}

文件内容：读取时注意文件的路径

driverClass = jdbc:mysql:jdbc.Driver

url = jdbc:mysql://localhost/count

user = root

password = 123456