Java操作数据库指南(之一)
Posted 大码王
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1、java操作mysql增删改查
package com.gr.DBHerpel; import java.sql.*; //导包 /** * ClassName: DBHerpel * @Description: TODO 数据库辅助类 * @author 情绪i */ public class DBHerpel { private static Connection Conn; // 数据库连接对象 // 数据库连接地址 private static String URL = "jdbc:mysql://localhost:3306/myschool?characterEncoding=utf8&useSSL=true"; // 数据库的用户名 private static String UserName = "root"; // 数据库的密码 private static String Password = "1234"; /** * * @Description: TODO 获取访问数据库的Connection对象 * @param @return * @return Connection 连接数据的对象 * @author 情绪i */ public static Connection getConnection() { try { Class.forName("com.mysql.jdbc.Driver"); // 加载驱动 System.out.println("加载驱动成功!!!"); } catch (ClassNotFoundException e) { // TODO: handle exception e.printStackTrace(); } try { //通过DriverManager类的getConenction方法指定三个参数,连接数据库 Conn = DriverManager.getConnection(URL, UserName, Password); System.out.println("连接数据库成功!!!"); //返回连接对象 return Conn; } catch (SQLException e) { // TODO: handle exception e.printStackTrace(); return null; } } }
2、增删改查
package com.gr.visitServer; import java.sql.Connection; import java.sql.ResultSet; import java.sql.Statement; import com.gr.DBHerpel.DBHerpel; public class VisitMySql { // 连接对象 private Connection conn; // 传递sql语句 private Statement stt; // 结果集 private ResultSet set; // 1、查询 public void Select() { try { // 获取连接 conn = DBHerpel.getConnection(); if (conn == null) return; // 定义sql语句 String Sql = "select * from login"; // 执行sql语句 stt = conn.createStatement(); // 返回结果集 set = stt.executeQuery(Sql); // 获取数据 while (set.next()) { System.out.println("用户名:" + set.getString(1) + "\\t密码:" + set.getString(2)); } } catch (Exception e) { e.printStackTrace(); } finally { // 释放资源 try { set.close(); conn.close(); } catch (Exception e2) { // TODO: handle exception } } } //2、增 // 使用Statement接口的executeUpdate()方法向数据库添加数据 public void Add(){ try { //获取连接 conn = DBHerpel.getConnection(); if(conn==null) return; //获取用户输入的账号和密码 Scanner input = new Scanner(System.in); System.out.print("请输入用户名:"); int user = input.nextInt(); System.out.print("请输入密码:"); String pwd = input.next(); //定义sql语句 String sql = "insert into login values("+user+" , \'"+pwd+"\');"; //获取Statement对象 stt = conn.createStatement(); //执行sql语句 stt.executeUpdate(sql); } catch (Exception e) { e.printStackTrace(); }finally{ //释放资源 try { conn.close(); } catch (Exception e2) {} } } //3、删 //使用Statement接口的executeUpdate()方法实现从数据库删除数据 public void Delete(){ try { //获取连接 conn = DBHerpel.getConnection(); if(conn==null) return; //提示用户输入要删除的用户 System.out.print("请输入删除的用户:"); Scanner input = new Scanner(System.in); int user = input.nextInt(); //定义sql语句 String deleteSql = "DELETE FROM login WHERE user="+user+";"; //获取Statement对象 stt = conn.createStatement(); //执行sql语句 stt.executeUpdate(deleteSql); } catch (Exception e) { e.printStackTrace(); }finally{ //释放资源 try { conn.close(); } catch (Exception e2) {} } } //4、改 //使用PreparedStatement接口中的executeUpdate()方法实现修改数据 public void Update(){ try { //获取连接 conn = DBHerpel.getConnection(); if(conn==null) return; //用户输入要修改的账户 System.out.print("请输入用户名:"); Scanner input = new Scanner(System.in); int user = input.nextInt(); //提示用户输入新的密码 System.out.print("请输入新的密码:"); String NewPwd = input.next(); //定义Sql语句 String UpdateSql = "UPDATE login SET pwd = \'"+NewPwd+"\' WHERE user = "+user+";"; //创建Statement对象 PreparedStatement ps = conn.prepareStatement(UpdateSql); //执行sql语句 ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); }finally{ //释放资源 try { conn.close(); } catch (Exception e2) {} } } }
3、测试
package com.gr.Test; import com.gr.visitServer.VisitMySql; public class Test { public static void main(String[] args) //实例化对象 VisitMySql vs = new VisitMySql(); //调用查询方法 vs.Select(); } }
1、帮助类
package oracle; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; /** * @description: Oracle连接工具类 */ public class DBUtil { //数据库连接地址 private static String url="jdbc:oracle:thin:@localhost:1521:orcl"; //用户名 private static String username= "system"; //密码 private static String password ="ZZZ111"; //驱动名称 private static String jdbcName = "oracle.jdbc.OracleDriver"; /*获取数据库连接 */ public static Connection getCon(){ try { Class.forName(jdbcName); } catch (ClassNotFoundException e) { e.printStackTrace(); } Connection con = null; try { con = DriverManager.getConnection(url,username,password); } catch (SQLException e) { e.printStackTrace(); } return con; } /*关闭数据库连接*/ public static void closeCon(Connection con) throws SQLException { if (con != null) con.close(); } public static void main(String[] args){ try { getCon(); System.out.println("数据库连接成功"); } catch (Exception e) { e.printStackTrace(); System.out.println("数据库连接失败"); } } }
2、增删改查
package oracle; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class OracleDemo { //连接对象 Connection connection=null; //创建预编译对象 PreparedStatement ps=null; //创建结果集 ResultSet rs = null; /*插入*/ public int insert(){ int result = 0; connection = DBUtil.getCon(); String sql = "insert into student values(?,?,?)"; try { ps = connection.prepareStatement(sql); ps.setInt(1,2); ps.setString(2,"老王"); ps.setString(3,"女"); result = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.closeCon(connection); } return result; } /*查询*/ public void select(){ connection = DBUtil.getCon(); String sql = "select id,name,gender from student"; try { ps = connection.prepareStatement(sql); rs = ps.executeQuery(); while (rs.next()){ int id = rs.getInt(1); String name = rs.getString(2); String gender = rs.getString(3); System.out.println("ID:"+id + " NAME:"+name+" GENDER:"+gender); } } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.closeCon(connection); } } /*修改*/ public int update(){ connection = DBUtil.getCon(); String sql = "update student set name = ?,gender = ? where id = ?"; int result = 0; try { ps = connection.prepareStatement(sql); ps.setString(1,"老张"); ps.setString(2,"男"); ps.setInt(3,2); result = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.closeCon(connection); } return result; } /*删除 */ public int delete(){ int result = 0; connection = DBUtil.getCon(); String sql = "delete from student where id = ?"; try { ps = connection.prepareStatement(sql); ps.setInt(1,1); result = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.closeCon(connection); } return result; } public static void main(String[] args){ OracleDemo od = new OracleDemo(); /*int add = od.add(); System.out.println(add);*/ od.select(); // System.out.println(od.delete()); } }
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