JDBCUtils 类的 创建 及 使用 (增删改查) 拼搏现实的明天。 2022-02-04 04:01 173阅读 0赞 **JDBCUtils的创建:** import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class JDBCUtils { //这个工具类,主要为我们获取一个数据库连接 private static String driverName = "com.mysql.jdbc.Driver"; private static String url = "jdbc:mysql://localhost:3306/day04"; private static String username = "root"; private static String password = "123"; //静态代码块,目的,让第一次使用到JDBCUtils中加载驱动,第二次以后不再加载了 static{ //1.加载驱动 try { Class.forName(driverName); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block //System.out.println("驱动加载失败..请检查驱动包"); throw new RuntimeException("驱动加载失败..请检查驱动包"); } } public static Connection getConnection() throws Exception{ //2.获取和数据库的连接 Connection conn = DriverManager.getConnection(url, username, password); //3.返回连接对象 return conn; } //关闭所有资源的统一代码 public static void closeAll(Connection conn,Statement st,ResultSet rs){ //负责关闭 if(conn != null){ try { conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if(st != null){ try { st.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if(rs != null){ try { rs.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } **JDBCUtils 的使用:** import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class TestDemo { public static void main(String[] args) { // 1.获取到数据库连接 Connection conn = null; // 2.通过连接对象, 获取SQL执行对象 Statement st = null; // 3.st执行sql语句 ResultSet rs = null; try { conn = JDBCUtils.getConnection(); st = conn.createStatement(); rs = st.executeQuery("select * from category"); // 4.处理结果集 while (rs.next()) { Object cid = rs.getObject("cid"); Object cname = rs.getObject("cname"); System.out.println(cid + "\t" + cname); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { // 5.释放资源 JDBCUtils.closeAll(conn, st, rs); } } } **JDBCUtils 的 增删改查 操作: ** import java.sql.Connection; import java.sql.ResultSet; import java.sql.Statement; public class TestDemo { public static void main(String[] args) { // TODO Auto-generated method stub //insert(); // delete(); // update(); // query(); } //插入 public static void insert(){ //1. Connection conn = null; //2. Statement st = null; //4. try{ conn = JDBCUtils.getConnection(); st = conn.createStatement(); int rows = st.executeUpdate("insert into category (cname) values ('饮料'),('灵饰'),('羽毛球')"); System.out.println("成功插入"+rows+"行!!!"); }catch(Exception e){ System.out.println(e); }finally { JDBCUtils.closeAll(conn, st,null); } } //删除 public static void delete(){ //1. Connection conn = null; //2. Statement st = null; //3. ResultSet rs = null; //4. try{ conn = JDBCUtils.getConnection(); st = conn.createStatement(); int rows = st.executeUpdate("delete from category where cname='饮料'"); System.out.println("成功删除"+rows+"行!!!"); }catch(Exception e){ System.out.println(e); }finally { JDBCUtils.closeAll(conn, st, rs); } } //修改 public static void update(){ //1. Connection conn = null; //2. Statement st = null; //3. ResultSet rs = null; //4. try{ conn = JDBCUtils.getConnection(); st = conn.createStatement(); int rows = st.executeUpdate("update category set cname='乒乓球类' where cid = 11"); System.out.println("成功修改"+rows+"行!!!"); }catch(Exception e){ System.out.println(e); }finally { JDBCUtils.closeAll(conn, st, rs); } } //查询 public static void query(){ //1. Connection conn = null; //2. Statement st = null; //3. ResultSet rs = null; //4. try{ conn = JDBCUtils.getConnection(); st = conn.createStatement(); rs = st.executeQuery("select * from category where cid= 14"); while(rs.next()){ Object cid = rs.getObject("cid"); Object cname = rs.getObject("cname"); System.out.println(cid+"\t"+cname); } }catch(Exception e){ System.out.println(e); }finally { JDBCUtils.closeAll(conn, st, rs); } } }
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