数据库连接

在java代码中连接数据库

 Class.forName("com.mysql.jdbc.Driver");
 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/spring", "root", "ocsoft");
 
 String sqlQuery = "select count(*) from user where username= ?";
 PreparedStatement psQuery = conn.prepareStatement(sqlQuery);
 psQuery.setString(1,username);
 ResultSet rs = psQuery.executeQuery();
 rs.next();
 int count = rs.getInt(1);//拿到字段值
 if (count > 0) {
  response.sendRedirect("registerFail.jsp");
  psQuery.close();
  conn.close();
  return;
 }
 
 String sql = "insert into user (username,password) values(?,?)";
 PreparedStatement ps = conn.prepareStatement(sql);
 ps.setString(1,username);
 ps.setString(2,password);
 ps.executeUpdate();
 ps.close();
 conn.close();