JDBC入门(一)基本CRUD操作

java连接数据库步骤(mysql):

加载驱动,获取连接,创建处理命令,执行sql命令,处理结果,关闭资源.

public class JDBCCrud {/** * 向表中添加数据  */public void insert(String username,String password){Connection conn = null;Statement stmt = null;try {//加载驱动Class.forName("com.mysql.jdbc.Driver");//获取连接conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");//创建处理命令stmt = conn.createStatement();//执行sql命令int i = stmt.executeUpdate("insert into user(username,password) values('"+username+"','"+password+"')");//处理结果if(i>0){System.out.println("操作成功,影响数据行数:"+i);}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}finally{try {//alt+shift+zif(stmt != null)stmt.close();if(conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}}public void login(String username,String password){Connection conn = null;Statement stmt = null;ResultSet rs = null;try {Class.forName("com.mysql.jdbc.Driver");conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");stmt = conn.createStatement();//执行查询操作获取结果集rs = stmt.executeQuery("select * from user where username='"+username+"' and password='"+password+"'");//取出结果集中的数据if(rs.next()){//根据数据表中的列名称以及类型从结果集中取出指定的列数据int id = rs.getInt("id");String uname = rs.getString("username");String pword = rs.getString("password");System.out.println(id+"--"+uname+"--"+pword);}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}finally{try {if(rs != null)rs.close();if(stmt != null)stmt.close();if(conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}}/** *查询所有操作 * */public void queryAll(){Connection conn = null;Statement stmt = null;ResultSet rs = null;try {Class.forName("com.mysql.jdbc.Driver");conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");stmt = conn.createStatement();//执行查询操作获取结果集rs = stmt.executeQuery("select id,username,password from user");//取出结果集中的数据while(rs.next()){//根据数据表中的列名称以及类型从结果集中取出指定的列数据int id = rs.getInt("id");String uname = rs.getString("username");String pword = rs.getString("password");System.out.println(id+"--"+uname+"--"+pword);}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}finally{try {if(rs != null)rs.close();if(stmt != null)stmt.close();if(conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}}/** * 删除数据操作 */ public void delete(int id){Connection conn = null;Statement stmt = null;try {Class.forName("com.mysql.jdbc.Driver");conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");stmt = conn.createStatement();int i = stmt.executeUpdate("delete from user where id="+id+"");if(i > 0){System.out.println("操作成功,影响数据行数:"+i);System.out.println("删除"+id+"号用户成功!");}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}finally{try {if(stmt != null)stmt.close();if(conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}}/** * 更新数据操作 */public void updete(int id,String username,String password){Connection conn = null;Statement stmt = null;try {Class.forName("com.mysql.jdbc.Driver");conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");stmt = conn.createStatement();int i = stmt.executeUpdate("update user set username='"+username+"',password='"+password+"' where id="+id+"");if(i>0){System.out.println("操作成功,影响数据行数:"+i);System.out.println("修改成功!");}} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}finally{try {if(stmt != null)stmt.close();if(conn != null)conn.close();} catch (SQLException e) {e.printStackTrace();}}}public static void main(String[] args) {int id = 1;String username = "rose";String password = "654321";JDBCCrud jdbc = new JDBCCrud();//jdbc.insert(username,password);//jdbc.queryAll();//jdbc.updete(id, username, password);//jdbc.delete(id);jdbc.login(username,password);}}