网站收费标准,wordpress并发亿万,资料图片 wordpress,网站搭建要求模板不使用任何工具类手动连接 package com.oracle.jdbc;import java.sql.*;/***jdbc查询 jdbc数据库下#xff0c;user表中所有数据并打印在控制台* jdbc操作数据库步骤* 1注册驱动* 2创建数据库连接对象* 3获取传输器对象* 4执行sql* 5处理结果集* 6释放资源*/public cla…不使用任何工具类手动连接 package com.oracle.jdbc;import java.sql.*;/***jdbc查询 jdbc数据库下user表中所有数据并打印在控制台* jdbc操作数据库步骤* 1注册驱动* 2创建数据库连接对象* 3获取传输器对象* 4执行sql* 5处理结果集* 6释放资源*/public class JDBCDemo1 {public static void main(String[] args) throws ClassNotFoundException, SQLException {Class.forName(com.mysql.cj.jdbc.Driver);String root root;String password root;// String url jdbc:mysql://localhost:3306/jdbc?useSSLfalseserverTimezoneUTCuseUnicodetruecharacterEncodingUTF-8;String url jdbc:mysql://localhost:3306/jdbc;Connection connection DriverManager.getConnection(url, root, password);System.out.println(connection);Statement statement connection.createStatement();String sql select * from user;ResultSet resultSet statement.executeQuery(sql);while(resultSet.next()){int id resultSet.getInt(id);String name resultSet.getString(name);String gender resultSet.getString(gender);int age resultSet.getInt(age);String address resultSet.getString(address);System.out.println(id , name ,gender,age,address );}resultSet.close();statement.close();connection.close();} }初步封装一下变成工具类 package com.march.mysql0314;import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException;public class DBUtil {private static final String URL jdbc:mysql://localhost:3306/empdb?useSSLfalsecharacterEncodingutf8serverTimezoneAsia/Shanghai;private static final String U com.mysql.cj.jdbc.Driver;private static final String USERNAME root;private static final String PASSWORLD root;private static Connection connection null;private DBUtil(){};public static Connection getConnection() throws SQLException, ClassNotFoundException {if (connection null || connection.isClosed()){Class.forName(U);connection DriverManager.getConnection(URL, USERNAME, PASSWORLD);}return connection;}public static void closeConnection(){try {if (!connection.isClosed()connection null){connection.close();}} catch (SQLException e) {e.printStackTrace();}}}使用属性集文件连接方便改写用户登录的数据 package com.march.mysql0314;import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.Properties;public class DBUtilPro {private static Connection connection null;private DBUtilPro(){};private static Properties properties new Properties();static{try(InputStream inputStream DBUtilPro.class.getResourceAsStream(/mysql.properties);){properties.load(inputStream);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}public static Connection getConnection() throws SQLException, ClassNotFoundException {if (connection null || connection.isClosed()){Class.forName(properties.getProperty(Driver));connection DriverManager.getConnection(properties.getProperty(URL),properties.getProperty(USERNAME),properties.getProperty(PASSWORLD));}return connection;}public static void closeConnection(){try {if (!connection.isClosed()connection null){connection.close();}} catch (SQLException e) {e.printStackTrace();}} }使用线程集合ThreadLocal实现同一事务的同一连接 package com.march.mysql0314;import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.Properties;public class DBUtilProMax {private DBUtilProMax(){};private static Properties properties new Properties();private static ThreadLocalConnection threadLocal new ThreadLocal();static{try(InputStream inputStream DBUtil.class.getResourceAsStream(/mysql.properties);){properties.load(inputStream);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}public static Connection getConnection() throws SQLException, ClassNotFoundException {Connection connection threadLocal.get();if (connection null || connection.isClosed()){Class.forName(properties.getProperty(Driver));connection DriverManager.getConnection(properties.getProperty(URL),properties.getProperty(USERNAME),properties.getProperty(PASSWORLD));threadLocal.set(connection);}return connection;}public static void closeConnection(){Connection connection threadLocal.get();try {if (!connection.isClosed()connection null){connection.close();}} catch (SQLException e) {e.printStackTrace();}} }使用德鲁伊连接池 package com.march.mysql0314;import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.Properties;public class DButilFinally {// 私有的构造方法private DButilFinally(){}//---1定义静态变量 : Propertiesprivate static Properties pro new Properties();// 1 创建DataSource对象private static DataSource ds null;//---2使用静态代码块,读取配置文件static{try(//2 获取流, 文件存储在src目录下InputStream in DBUtil.class.getResourceAsStream(/druid.properties);){//把IO中的属性集加载到properties对象中pro.load(in);//获取数据源对象ds DruidDataSourceFactory.createDataSource(pro);} catch (Exception e) {e.printStackTrace();}}// ---- 使用ThreadLocal存储连接对象//1 定义ThreadLocalprivate static ThreadLocalConnection local new ThreadLocal();/*** 获取连接的方法* return* throws SQLException* throws ClassNotFoundException*/public static Connection getConn() throws SQLException, ClassNotFoundException {// --2 从ThreadLocal中获取连接对象Connection conn local.get();if(conn null || conn.isClosed()){//通过DataSource获取连接对象conn ds.getConnection();// ---3 向ThreadLocal中存储连接对象local.set(conn);;}return conn;}/*** 关闭连接的方法*/public static void closeConn(){// // --2 从ThreadLocal中获取连接对象Connection conn local.get();try {if(conn!null !conn.isClosed()){ //conn不是null ,同时也没有关闭conn.close();}} catch (SQLException e) {e.printStackTrace();}finally {// -- 删除ThreadLocal中存储的数据local.remove();}}}