脚本宝典收集整理的这篇文章主要介绍了Java知识点总结(JDBC-连接步骤及CRUD),脚本宝典觉得挺不错的,现在分享给大家,也给大家做个参考。
Java知识点总结(JDBC-连接步骤及CRUD)
@(Java知识点总结)[Java, JDBC]
连接数据库步骤
依序关闭使用的对象连接:
- ResultSet -> Statement -> Connection
CRUD操作
import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class StudentDao { private static Connection getConn() { String driver = "com.mysql.jdbc.Driver"; String url = "jdbc:mysql://localhost:3306/test"; String username = "root"; String password = "123"; Connection conn = null; try { Class.forName(driver); //classLoader,加载对应驱动 //建立连接(连接对象内部包含了Socket对象,是一个远程连接。比较耗时!这是Connection对象管理的一个要点!) //真正开发中,为了提高效率,都会使用连接池来管理连接对象! conn = (Connection) DriverManager.getConnection(url, username, password); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } return conn; } private static int insert(User user) { Connection conn = getConn(); int i = 0; String sql = "insert into users (Name,Sex,Age) values(?,?,?)"; PreparedStatement pstmt = null; try { pstmt = (PreparedStatement) conn.prepareStatement(sql); pstmt.setString(1, user.getName()); pstmt.setString(2, user.getSex()); pstmt.setInt(3, user.getAge()); i = pstmt.executeUpdate(); pstmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); }finally { try { pstmt.close(); } catch (SQLException e) { e.printStackTrace(); } try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return i; } private static int update(User user) { Connection conn = getConn(); int i = 0; String sql = "update users set Age='" + user.getAge() + "' where Name='" + user.getName() + "'"; PreparedStatement pstmt = null; try { pstmt = (PreparedStatement) conn.prepareStatement(sql); i = pstmt.executeUpdate(); System.out.println("resutl: " + i); pstmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); }finally { try { pstmt.close(); } catch (SQLException e) { e.printStackTrace(); } try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return i; } private static Integer getAll() { Connection conn = getConn(); String sql = "select * from users"; PreparedStatement pstmt =null; ResultSet rs = null; try { pstmt = (PreparedStatement)conn.prepareStatement(sql); rs = pstmt.executeQuery(); int col = rs.getMetaData().getColumnCount(); System.out.println("============================"); while (rs.next()) { for (int i = 1; i <= col; i++) { System.out.print(rs.getString(i) + "t"); if ((i == 2) && (rs.getString(i).length() < 8)) { System.out.print("t"); } } System.out.println(""); } System.out.println("============================"); } catch (SQLException e) { e.printStackTrace(); }finally { try { rs.close(); } catch (SQLException e1) { e1.printStackTrace(); } try { pstmt.close(); } catch (SQLException e) { e.printStackTrace(); } try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return null; } private static int delete(String name) { Connection conn = getConn(); int i = 0; String sql = "delete from users where Name='" + name + "'"; PreparedStatement pstmt = null; try { pstmt = (PreparedStatement) conn.prepareStatement(sql); i = pstmt.executeUpdate(); System.out.println("resutl: " + i); pstmt.close(); conn.close(); } catch (SQLException e) { e.printStackTrace(); }finally { try { pstmt.close(); } catch (SQLException e) { e.printStackTrace(); } try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } return i; } public static void main(String[] args) { getAll(); insert(new User("张柏芝", "女", 43)); getAll(); update(new User("张三", "", 38)); delete("Achilles"); getAll(); } }
public class User { private int id; private int age; private String name ; private String sex; public User( String name, String sex,int age) { this(); this.age = age; this.name = name; this.sex = sex; } public User() { } public int getAge() { return age; } public int getId() { return id; } public String getName() { return name; } public String getSex() { return sex; } public void setAge(int age) { this.age = age; } public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } public void setSex(String sex) { this.sex = sex; } }
执行结果:
以上是脚本宝典为你收集整理的Java知识点总结(JDBC-连接步骤及CRUD)全部内容,希望文章能够帮你解决Java知识点总结(JDBC-连接步骤及CRUD)所遇到的问题。
本图文内容来源于网友网络收集整理提供,作为学习参考使用,版权属于原作者。
如您有任何意见或建议可联系处理。小编QQ:384754419,请注明来意。