JAVA学习笔记(五十)- JDBC Java数据库连接

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JDBC操作步骤

/* * JDBC操作步骤 *   */public class Test01 {    public static void main(String[] args) {        try {            //1.加载并注册驱动            Class.forName("com.mysql.jdbc.Driver");            //DriverManager.registerDriver(new com.mysql.jdbc.Driver());            System.out.println("注册驱动成功！");            //2.获取数据库连接Connection            String url="jdbc:mysql://localhost:3306/test";            String user="root";            String password="123456";            Connection conn=DriverManager.getConnection(url, user, password);            System.out.println("连接数据库成功！");            //3.创建Statement，并执行sql语句            Statement stmt=conn.createStatement();            String sql="insert into user values (null,'蒋输','111111',21,'2012-1-11')";            int num=stmt.executeUpdate(sql);            //4.处理执行结果             if(num>0){                System.out.println("插入成功！");            }else{                System.out.println("插入失败！");            }            //5.关闭资源            stmt.close();            conn.close();        } catch (ClassNotFoundException e) {            System.out.println("驱动没找到！");            e.printStackTrace();        } catch (SQLException e) {            System.out.println("数据库连接失败！");            e.printStackTrace();        }    }}

JDBC实现查询操作

import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.Date;/* * JDBC实现查询操作 */public class Test02 {    Connection conn = null;    Statement stmt = null;    ResultSet rs = null;    // 查询用户信息        public void queryUsers() {            try {                //1.加载并注册驱动                Class.forName("com.mysql.jdbc.Driver");                //2.获取数据库连接                conn = DriverManager.getConnection(                        "jdbc:mysql://localhost:3306/test", "root", "123456");                //3.创建Statement对象并执行SQL语句                stmt = conn.createStatement();                String sql = "select * from user";                //调用executeQuery()方法执行查询操作，返回一个ResultSet结果集，包含查询的结果                rs = stmt.executeQuery(sql);                //4.操作ResultSet结果集                while (rs.next()) { //将指针向前移动一行，判断是否有记录                    int id = rs.getInt("id"); //根据列名获取值                    String name = rs.getString("name");                    String password = rs.getString(3);//根据列的索引获取值                    java.sql.Date birthday=rs.getDate(5);                    System.out.println("编号:" + id + ",姓名：" + name + ",密码："                            + password+" 生日："+birthday);                }            } catch (ClassNotFoundException e) {                e.printStackTrace();            } catch (SQLException e) {                e.printStackTrace();            } finally {                //5.关闭资源                try {                    rs.close();                    stmt.close();                    conn.close();                } catch (SQLException e) {                    e.printStackTrace();                }            }        }    //查询用户数量    public void queryUserCount() {        try {            //1.加载并注册驱动            Class.forName("com.mysql.jdbc.Driver");            //2.获取数据库连接            conn = DriverManager.getConnection(                    "jdbc:mysql://localhost:3306/test", "root", "123456");            //3.创建Statement对象并执行SQL语句            stmt = conn.createStatement();            String sql = "select count(id) from user";            //调用executeQuery()方法执行查询操作，返回一个ResultSet结果集，包含查询的结果            rs = stmt.executeQuery(sql);            //4.操作ResultSet结果集            int count=0;            if (rs.next()) { //将指针向前移动一行，判断是否有记录                count=rs.getInt(1);            }            System.out.println("共有"+count+"个用户！");        } catch (ClassNotFoundException e) {            e.printStackTrace();        } catch (SQLException e) {            e.printStackTrace();        } finally {            //5.关闭资源            try {                rs.close();                stmt.close();                conn.close();            } catch (SQLException e) {                e.printStackTrace();            }        }    }    public static void main(String[] args) {        new Test02().queryUserCount();    }}

将数据库连接信息保存在文件中

import java.io.FileInputStream;import java.io.IOException;import java.sql.Connection;import java.sql.DriverManager;import java.util.Properties;/* * 将数据库连接信息保存在文件中 */public class Test03 {    public static void main(String[] args) throws Exception {        Properties p=new Properties();        p.load(new FileInputStream("jdbc.properties"));        Class.forName("com.mysql.jdbc.Driver");        Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/test", p);        System.out.println("连接数据库成功！ ");    }}

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